Search

Pregnant people are vulnerable to air pollution exposure, including risk of preterm birth, low birth weight, and stillbirth. Understanding the infiltration of outdoor wildfire smoke into a residential space is critical for the accurate assessment of wildfire smoke exposure and associated health effects in pregnant people. Relying on ambient measurements of wildfire smoke alone can result in exposure misclassification. In this study, we examine the role of physical housing characteristics in the relationship between smoke exposure and preterm birth. In particular, we examine the effect of home size, year of construction, cooling type, and renovation status, as effect modifiers in the relationship between smoke exposure during pregnancy and preterm birth from 2007 to 2015 in California. To do this, we combined data on home characteristics from the California Tax Assessor, birth outcomes from the California birth records database, and the number of smoke days for each pregnancy from the NOAA (National Oceanic and Atmospheric Administration) Hazard Mapping System (HMS). We estimated the association between smoke day exposures and odds of preterm birth using logistic regression models and stratified by air basin and housing characteristics. Our findings reveal that cooling type and renovation status are key factors modifying the smoke exposure-preterm birth relationship. Notably, we found elevated associations for people living in unrenovated homes, those using evaporative cooling systems, and those using central air conditioning units. While we observed elevated odds of preterm birth associated with increasing smoke day exposure for residents of large and new homes, this effect does not significantly differ across home size and age quartiles. This study highlights the need to further examine the relative roles of housing characteristics as well as factors not measured here including behavioral factors, time spent outdoors, window use, and occupational exposures in driving adverse birth outcomes related to wildfire smoke exposure., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Relative to other Oregon counties, Klamath County experiences worse air quality due to wildfire smoke, as well as elevated rates of infant mortality and low birthweight. Klamath County Public Health (KCPH) raised concerns that wildfire smoke is a contributor to poor infant health. Thus, we built a multidisciplinary team and designed a community-engaged research (CEnR) project to capture community and individual-level exposure to wildfire smoke contaminants, alongside perinatal health outcomes. Through partnerships, we identified 24 individuals across academic, public health, and community organizations that met five times over three months to develop a study design. We initially used a modified Delphi method, but adjusted our approach to find multidisciplinary areas of agreement across a highly diverse team. Our team used structured meetings, surveys, and iterative feedback to build consensus on a study design. KCPH and our community partners reviewed and approved all proposed activities to ensure community input was integrated. The resultant study, trialed in Klamath County, included the use of environmental, residential, and personal samplers and health surveys with a cohort of pregnant individuals during the wildfire season. We discuss the advantages and challenges of building a multidisciplinary CEnR study in a rural county disproportionately impacted by wildfire smoke and infant mortality.

Wildfires have become common global phenomena concurrent with warmer and drier climates and are now major contributors to ambient air pollution worldwide. Exposure to wildfire smoke has been classically associated with adverse cardiopulmonary health outcomes, especially in vulnerable populations. Recent work has expanded our understanding of wildfire smoke toxicology to include effects on the central nervous system and reproductive function; however, the neurotoxic profile of this toxicant remains ill-explored in an occupational context. Here, we sought to address this by using RNA sequencing to examine transcriptomic signatures in the prefrontal cortex of male mice modeling career wildland firefighter smoke exposure. We report robust changes in gene expression profiles between smoke-exposed samples and filtered air controls, evidenced by 2,862 differentially expressed genes (51.2% increased). We further characterized the functional relevance of these genes highlighting enriched pathways related to synaptic transmission, neuroplasticity, blood-brain barrier integrity, and neurotransmitter metabolism. Additionally, we identified possible contributors to these alterations through protein-protein interaction network mapping, which revealed a central node at ß-catenin and secondary hubs centered around mitochondrial oxidases, the Wnt signaling pathway, and gene expression machinery. The data reported here will serve as the foundation for future experiments aiming to characterize the phenotypic effects and mechanistic underpinnings of occupational wildfire smoke neurotoxicology., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Wildfire smoke exposure alters grape composition, potentially resulting in "smoke tainted" wines. This has been correlated with elevated levels of smoke-derived volatile phenols (VPs) in grapes and wines. This work sought to create a predictive tool that could correlate levels of VPs in smoke with concentrations in grapes and wines. Therefore, passive samplers and Cabernet Sauvignon grapes were intentionally exposed to various smoke intensities, and wines were made thereafter. As expected, concentrations of VPs in grapes and wines were positively associated with the intensity of smoke exposure. Interestingly, levels of guaiacol in the passive samplers had a strong positive correlation with concentrations in grapes (R 2  = 0.9999) and wines (R 2  = 0.9998). The passive samplers were able to accurately predict guaiacol levels in smoke exposed grapes and wines with percent errors ranging from 0.08 to 11.3 %. These results suggest the capability of passive samplers to act as a monitoring system in vineyards during smoke events., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Anthony Wexler reports financial support was provided by University of California Davis Environmental Health Sciences Center. Anthony Wexler reports financial support was provided by USDA-NIFA-SCRI Award. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

The frequency, duration, and size of wildfires have been increasing, and the inhalation of wildfire smoke particles poses a significant risk to human health. Epidemiological studies have shown that wildfire smoke exposure is positively associated with cognitive and neurological dysfunctions. However, there is a significant gap in knowledge on how wildfire smoke exposure can affect the blood-brain barrier and cause molecular and cellular changes in the brain. Our study aims to determine the acute effect of smoldering eucalyptus wood smoke extract (WSE) on brain endothelial cells for potential neurotoxicity in vitro. Primary human brain microvascular endothelial cells (HBMEC) and immortalized human brain endothelial cell line (hCMEC/D3) were treated with different doses of WSE for 24 h. WSE treatment resulted in a dose-dependent increase in IL-8 in both HBMEC and hCMEC/D3. RNA-seq analyses showed a dose-dependent upregulation of genes involved in aryl hydrocarbon receptor (AhR) and nuclear factor erythroid 2-related factor 2 (NRF2) pathways and a decrease in tight junction markers in both HBMEC and hCMEC/D3. When comparing untreated controls, RNA-seq analyses showed that HBMEC have a higher expression of tight junction markers compared to hCMEC/D3. In summary, our study found that 24 h WSE treatment increases IL-8 production dose-dependently and decreases tight junction markers in both HBMEC and hCMEC/D3 that may be mediated through the AhR and NRF2 pathways, and HBMEC could be a better in vitro model for studying the effect of wood smoke extract or particles on brain endothelial cells.

Living conditions are an important modifier of individual health outcomes and may lead to higher allostatic load (AL). However, housing-induced cardiovascular and immune effects contributing to altered environmental responsiveness remain understudied. This investigation was conducted to examine the influence of enriched (EH) versus depleted housing (DH) conditions on cardiopulmonary functions, systemic immune responses, and allostatic load in response to a single wildfire smoke (WS) exposure in mice. Male and female C57BL/6J mice were divided into EH or DH for 22 weeks, and cardiopulmonary assessments measured before and after exposures to either one-hr filtered air (FA) or flaming eucalyptus WS exposure. Male and female DH mice exhibited increased heart rate (HR) and left ventricular mass (LVM), as well as reduced stroke volume and end diastolic volume (EDV) one week following exposure to WS. Female DH mice displayed significantly elevated levels of IL-2, IL-17, corticosterone and hemoglobin A1c (HbA1c) following WS, while female in EH mice higher epinephrine levels were detected. Female mice exhibited higher AL than males with DH, which was potentiated post-WS exposure. Thus, DH increased susceptibility to extreme air pollution in a gender-dependent manner suggesting that living conditions need to be evaluated as a modifier of toxicological responses.

Wildfire activity is increasing globally. The resulting smoke plumes can travel hundreds to thousands of kilometers, reflecting or scattering sunlight and depositing particles within ecosystems. Several key physical, chemical, and biological processes in lakes are controlled by factors affected by smoke. The spatial and temporal scales of lake exposure to smoke are extensive and under-recognized. We introduce the concept of the lake smoke-day, or the number of days any given lake is exposed to smoke in any given fire season, and quantify the total lake smoke-day exposure in North America from 2019 to 2021. Because smoke can be transported at continental to intercontinental scales, even regions that may not typically experience direct burning of landscapes by wildfire are at risk of smoke exposure. We found that 99.3% of North America was covered by smoke, affecting a total of 1,333,687 lakes ≥10 ha. An incredible 98.9% of lakes experienced at least 10 smoke-days a year, with 89.6% of lakes receiving over 30 lake smoke-days, and lakes in some regions experiencing up to 4 months of cumulative smoke-days. Herein we review the mechanisms through which smoke and ash can affect lakes by altering the amount and spectral composition of incoming solar radiation and depositing carbon, nutrients, or toxic compounds that could alter chemical conditions and impact biota. We develop a conceptual framework that synthesizes known and theoretical impacts of smoke on lakes to guide future research. Finally, we identify emerging research priorities that can help us better understand how lakes will be affected by smoke as wildfire activity increases due to climate change and other anthropogenic activities., (© 2024 Oak Ridge National Laboratory and The Author(s). Global Change Biology published by John Wiley & Sons Ltd.)

Background: Population growth and climate change have led to more frequent and larger wildfires, increasing the exposure of individuals to wildfire smoke. Notably, asthma exacerbations and allergic airway sensitization are prominent outcomes of such exposure., Summary: Key research questions relate to determining the precise impact on individuals with asthma, including the severity, duration, and long-term consequences of exacerbations. Identifying specific risk factors contributing to vulnerability, such as age, genetics, comorbidities, or environmental factors, is crucial. Additionally, reliable biomarkers for predicting severe exacerbations need exploration. Understanding the long-term health effects of repeated wildfire smoke exposures in individuals with asthma and addressing healthcare disparities are important research areas., Key Messages: This review discusses the need for comprehensive research efforts to better grasp wildfire smoke-induced respiratory health, particularly in vulnerable populations such as farmworkers, firefighters, pregnant women, children, the elderly, and marginalized communities. Effective mitigation would require addressing the current limitations we face by supporting research aimed at a better understanding of wildfire smoke-induced airway disease., (© 2024 S. Karger AG, Basel.)

Background: Wildfires are a global concern due to their wide-ranging environmental, economic, and public health impacts. Climate change contributes to an increase in the frequency and intensity of wildfires making smoke exposure a more significant and recurring health concern for individuals with airway diseases. Some of the most prominent effects of wildfire smoke exposure are asthma exacerbations and allergic airway sensitization. Likely due to the delayed recognition of its health impacts in comparison with cigarette smoke and industrial or traffic-related air pollution, research on the composition, the mechanisms of toxicity, and the cellular/molecular pathways involved is poor or non-existent., Summary: This review discusses potential underlying pathological mechanisms of wildfire-smoke-related allergic airway disease and asthma. We focused on major gaps in understanding the role of wildfire smoke composition in the development of airway disease and the known and potential mechanisms involving cellular and molecular players of oxidative injury at the epithelial barrier in airway inflammation. We examine how PM2.5, VOCs, O3, endotoxin, microbes, and toxic gases may affect oxidative stress and inflammation in the respiratory mucosal barrier. We discuss the role of AhR in mediating smoke's effects in alarmin release and IL-17A production and how glucocorticoid responsiveness may be impaired by IL-17A-induced signaling and epigenetic changes leading to steroid-resistant severe airway inflammation., Key Message: Effective mitigation of wildfire-smoke-related respiratory health effects would require comprehensive research efforts aimed at a better understanding of the immune regulatory effects of wildfire smoke in respiratory health and disease., (© 2024 S. Karger AG, Basel.)

In response to wildfire-related air quality issues as well as those associated with winter wood stove use and prescribed and agricultural burning, Clean Air Methow's Clean Air Ambassador program established a community air monitoring network (CAMN) to provide geospatially specific air quality information and supplement data generated by the two Washington State Department of Ecology nephelometers situated in the area. Clean Air Ambassadors (CAAs) were purposefully selected to host low-cost air sensors based on their geographic location and interest in air quality. All 18 CAAs were interviewed to understand their motivations for participation, experiences using the data, challenges encountered, and recommendations for future project directions. Interview transcripts were coded, and a qualitative analysis approach was used to identify the key themes in each domain. The reported motivations for participation as a CAA included reducing personal exposure, protecting sensitive populations, interest in air quality or environmental science, and providing community benefits. CAAs used CAMN data to understand air quality conditions, minimize personal or familial exposure, and engage other community members in air quality discussions. Opportunities for future project directions included use for monitoring other seasonal air quality issues, informing or reducing other pollution-generating activities, school and community educational activities, opportunities for use by and engagement of different stakeholder groups, and mobile-friendly access to CAMN information. Limited challenges associated with participation were reported. Additional research is necessary to understand the community-level impacts of the CAMN. The findings may be informative for other rural wildfire smoke-prone communities establishing similar CAMNs.

Objective: Wildfire smoke is an important source of air pollution associated with a range of cardiopulmonary health conditions. The Air Quality Health Index (AQHI) is the most widely used tool in Canada to communicate with the public about air pollution, but it may not adequately reflect health risks from wildfire smoke. The objective of this study was to evaluate the ability of the AQHI and four alternate AQHI-Plus amendments to predict adverse population health effects from wildfire smoke., Methods: The maximum 1-h values of the AQHI and the four amendments were calculated for each 48-h period of the wildfire seasons from 2010 to 2017 for 32 health units in British Columbia. Generalized Poisson models were used to estimate the association between these values and daily counts of five health outcomes: all-cause mortality; physician visits for all circulatory causes; visits for all respiratory causes, including asthma; asthma-specific visits; and dispensations of salbutamol sulfate (i.e., Ventolin®). Model fit was evaluated with the Akaike information criterion., Results: The AQHI and the four amendments were all associated with all five health outcomes. The AQHI exhibited best fit to the all-cause mortality and circulatory physician visits during all wildfire seasons, while the 1-h PM 2.5 Only AQHI-Plus exhibited best fit to the asthma-related outcomes during all wildfire seasons., Conclusion: Individuals with common respiratory conditions such as asthma and chronic obstructive pulmonary disease are particularly susceptible to wildfire smoke. As such, the 1-h PM 2.5 Only AQHI-Plus amendment was recommended for communicating about potential health effects of air quality during wildfire seasons in BC.

Background: Wildfire events are increasing in prevalence in the western United States. Research has found mixed results on the degree to which exposure to wildfire smoke is associated with an increased risk of mortality., Methods: We tested for an association between exposure to wildfire smoke and non-traumatic mortality in Washington State, USA. We characterized wildfire smoke days as binary for grid cells based on daily average PM 2.5 concentrations, from June 1 through September 30, 2006-2017. Wildfire smoke days were defined as all days with assigned monitor concentration above a PM 2.5 value of 20.4 μg/m 3 , with an additional set of criteria applied to days between 9 and 20.4 μg/m 3 . We employed a case-crossover study design using conditional logistic regression and time-stratified referent sampling, controlling for humidex., Results: The odds of all-ages non-traumatic mortality with same-day exposure was 1.0% (95% CI: - 1.0 - 4.0%) greater on wildfire smoke days compared to non-wildfire smoke days, and the previous day's exposure was associated with a 2.0% (95% CI: 0.0-5.0%) increase. When stratified by cause of mortality, odds of same-day respiratory mortality increased by 9.0% (95% CI: 0.0-18.0%), while the odds of same-day COPD mortality increased by 14.0% (95% CI: 2.0-26.0%). In subgroup analyses, we observed a 35.0% (95% CI: 9.0-67.0%) increase in the odds of same-day respiratory mortality for adults ages 45-64., Conclusions: This study suggests increased odds of mortality in the first few days following wildfire smoke exposure. It is the first to examine this relationship in Washington State and will help inform local and state risk communication efforts and decision-making during future wildfire smoke events.

Colorado is regularly impacted by long-range transport of wildfire smoke from upwind regions. This smoke is a major source of ambient PM 2.5 . Maternal exposure to total PM 2.5 during pregnancy has been linked to decreased birth weight and other adverse outcomes, although the impact of wildfire smoke contribution has only recently been investigated. The objective of this study was to estimate associations between adverse pregnancy outcomes and ambient wildfire smoke PM 2.5 . Wildfire smoke PM 2.5 exposures were estimated using a previously published method incorporating ground-based monitors and remote sensing data. Logistic regression models stratified by ZIP code and mixed models with random intercept by ZIP code were used to test for associations. The primary outcomes of interest were preterm birth and birth weight. Secondary outcomes included gestational hypertension, gestational diabetes, neonatal intensive care unit admission, assisted ventilation, small for gestational age, and low birth weight. Exposure to wildfire smoke PM 2.5 over the full gestation and during the second trimester were positively associated with pre-term birth (OR = 1.076 (μg/m 3 ) -1 [95% CI = 1.016, 1.139; p = 0.013] and 1.132 (μg/m 3 ) -1 [95% CI = 1.088, 1.178]; p < 0.0001, respectively), while exposure during the first trimester was associated with decreased birth weight (-5.7 g/(μg/m 3 ) [95% CI: -11.1, -0.4; p = 0.036]). Secondary outcomes were mixed.

Epidemiological studies of wildfire PM 2.5 constituents are hindered by the limited information on the population exposure to ambient PM 2.5 constituents during high-pollution episodes from wildfires ("smoke waves"). The chemical composition of wildfire-related PM 2.5 can be affected by different ecosystems. Current literature assessing the differences in PM 2.5 pollution from wildfire smoke by ecosystems often analyzes air samples collected from the smoke near the center of an individual fire, but the results might not represent the exposure of the general public living away from the fire center but affected by the smoke of the fire. We assessed the population-based exposure to wildfire-related PM 2.5 species by integrating monitor measurements on 29 PM 2.5 species and previous findings on smoke waves during 2004-2009 in 51 Western US counties across six ecoregions. We found that across all ecoregions, smoke waves were associated with an increase in the fraction of organic carbon of total PM 2.5 by 20 percentage points (95% confidence interval (CI): 17, 23), an increase in the fraction of elemental carbon by 0.99 percentage points (95% CI: 0.43, 1.6), and decreases in fractions of sulfate and crustal species. While the PM 2.5 mixtures were dominated by the same source (wildfires), compositions in North American Deserts and the Great Plains during smoke waves were distinct. Besides expanding the knowledge of wildfire PM 2.5 , our study has implications beyond wildfires and could aid future population-based epidemiological research on PM 2.5 mixtures by source and region.

Background : As climate change is expected to result in more frequent, larger fires and associated smoke impacts, creating and sustaining wildfire smoke-resilient communities is an urgent public health priority. Following two summers of persistent and extreme wildfire smoke events in Washington state, the need for additional research on wildfire smoke health impacts, risk communication, and risk reduction, and an associated greater coordination between researcher and practitioner communities, is of paramount importance. Objectives: On 30 October 2018, the University of Washington hosted a Wildfire Smoke Risk Communication Stakeholder Synthesis Symposium in Seattle, Washington. The goals of the symposium were to identify and prioritize practice-based information gaps necessary to promote effective wildfire smoke risk communication and risk reduction across Washington state, foster collaboration among practitioners and academics to address information gaps using research, and provide regional stakeholders with access to the best available health and climate science about current and future wildfire risks. Methods : Seventy-six Washington state practitioners and academics with relevant professional responsibilities or expertise in wildfire smoke and health engaged in small group discussions using the "World Café Method" to identify practice-relevant research needs related to wildfire smoke and health. Notes from each discussion were coded and qualitatively analyzed using a content analysis approach. Discussion : Washington state's public health and air quality practitioners need additional evidence to communicate and reduce wildfire smoke risk. Exposure, health risk, risk communication, behavior change and interventions, and legal and policy research needs were identified, along with the need to develop research infrastructure to support wildfire smoke and health science. Practice-relevant, collaborative research should be prioritized to address this increasing health threat.

Epidemiological studies consistently show an association between wildfire-related smoke exposure and adverse respiratory health. We conducted a systematic review of evidence in published literature pertaining to heterogeneity of respiratory effects from this exposure in North America. We calculated the within-study ratio of relative risks (RRR) and 95% confidence intervals (CI) to examine heterogeneity of effect by population subgroup, and then summarized the RRRs using meta-analysis. We found evidence of a greater effect of wildfire smoke on respiratory health among females relative to males for asthma (RRR: 1.035, 95% CI: 1.013, 1.057) and chronic obstructive pulmonary disease (RRR: 1.018, 95% CI: 1.003, 1.032). There was evidence of a lower relative risk for all respiratory outcomes among youth compared to adults (RRR: 0.976, 95% CI: 0.963, 0.989). We also found wildfire smoke effects stratified by income, race, education, health behaviors, access to care, housing occupancy, geographic region, and urban/rural status. However, data were insufficient to quantitatively evaluate effect modification by these characteristics. While we found evidence that certain demographic subgroups of the population are more susceptible to respiratory health outcomes from wildfire smoke, it is unclear whether this information can be used to inform policy aimed to reduce health impact of wildfires.

Wildfire episodes pose a significant public health threat in the United States. Adverse health impacts associated with wildfires occur near the burn area as well as in places far downwind due to wildfire smoke exposures. Health effects associated with exposure to particulate matter arising from wildfires can range from mild eye and respiratory tract irritation to more serious outcomes such as asthma exacerbation, bronchitis, and decreased lung function. Real-time operational forecasts of wildfire smoke concentrations are available but they are not readily integrated with information on vulnerable populations necessary to identify at-risk communities during wildfire smoke episodes. Efforts are currently underway at the Centers for Disease Control and Prevention (CDC) to develop an online tool that utilizes short-term predictions and forecasts of smoke concentrations and integrates them with measures of population-level vulnerability for identifying at-risk populations to wildfire smoke hazards. The tool will be operationalized on a national scale, seeking input and assistance from several academic, federal, state, local, Tribal, and Territorial partners. The final product will then be incorporated into CDC's National Environmental Public Health Tracking Network (http://ephtracking.cdc.gov), providing users with access to a suite of mapping and display functionalities. A real-time vulnerability assessment tool incorporating standardized health and exposure datasets, and prevention guidelines related to wildfire smoke hazards is currently unavailable for public health practitioners and emergency responders. This tool could strengthen existing situational awareness competencies, and expedite future response and recovery efforts during wildfire episodes., (Published by Elsevier B.V.)

Recent growth in the frequency and severity of US wildfires has led to more wildfire smoke and increased public exposure to harmful air pollutants. Populations exposed to wildfire smoke experience a variety of negative health impacts, imposing economic costs on society. However, few estimates of smoke health costs exist and none for the entire Western US, in particular, which experiences some of the largest and most intense wildfires in the US. The lack of cost estimates is troublesome because smoke health impacts are an important consideration of the overall costs of wildfire. To address this gap, this study provides the first time series estimates of PM2.5 smoke costs across mortality and several morbidity measures for the Western US over 2005-2015. This time period includes smoke from several megafires and includes years of record-breaking acres burned. Smoke costs are estimated using a benefits transfer protocol developed for contexts when original health data are not available. The novelty of our protocol is that it synthesizes the literature on choices faced by researchers when conducting a smoke cost benefit transfer. On average, wildfire smoke in the Western US creates $165 million in annual morbidity and mortality health costs.

Wildfires burn more than 7 million acres in the United States annually, according to the US Forest Service. Little is known about which subpopulations are more vulnerable to health risks from wildfire smoke, including those associated with fine particulate matter. We estimated exposure to fine particles specifically from wildfires, as well as the associations between the presence of wildfire-specific fine particles and the amount of hospital admissions for respiratory causes among subpopulations older than 65 years of age in the western United States (2004-2009). Compared with other populations, higher fractions of persons who were black, lived in urban counties, and lived in California were exposed to more than 1 smoke wave (high-pollution episodes from wildfire smoke). The risks of respiratory admissions on smoke-wave days compared with non-smoke-wave days increased 10.4% (95% confidence interval: 1.9, 19.6) for women and 21.7% (95% confidence interval: 0.4, 47.3) for blacks. Our findings suggest that increased risks of respiratory admissions from wildfire smoke was significantly higher for women than for men (10.4% vs. 3.7%), blacks than whites (21.7% vs. 6.9%), and, although associations were not statistically different, people in lower-education counties than higher-educated counties (12.7% vs. 6.1%). Our study raised important environmental justice issues that can inform public health programs and wildfire management. As climate change increases the frequency and intensity of wildfires, evidence on vulnerable subpopulations can inform disaster preparedness and the understanding of climate change consequences., (© The Author(s) 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

BACKGROUND: Wildfire smoke exposure has become a growing public health concern, as megafires and fires at the wildland urban interface increase in incidence and severity. Smoke contains many pollutants that negatively impact health and is linked to a number of health complications and chronic diseases. Communicating effectively with the public, especially at-risk populations, to reduce their exposure to this environmental pollutant has become a public health priority. Although wildfire smoke risk communication research has also increased in the past decade, best practice guidance is limited, and most health communications do not adhere to health literacy principles: readability, accessibility, and actionability. This scoping review identifies peer-reviewed studies about wildfire smoke risk communications to identify gaps in research and evaluation of communications and programs that seek to educate the public. METHODS: Four hundred fifty-one articles were identified from Web of Science and PubMed databases. After screening, 21 articles were included in the final sample for the abstraction process and qualitative thematic analysis. Ten articles were based in the US, with the other half in Australia, Canada, Italy, and other countries. Fifteen articles examined communication materials and messaging recommendations. Eight papers described communication delivery strategies. Eleven articles discussed behavior change. Six articles touched on risk communications for vulnerable populations; findings were limited and called for increasing awareness and prioritizing risk communications for at-risk populations. RESULTS: This scoping review found limited studies describing behavior change to reduce wildfire smoke exposure, characteristics of effective communication materials and messaging, and communication delivery strategies. Literature on risk communications, dissemination, and behavior change for vulnerable populations was even more limited. CONCLUSIONS: Recommendations include providing risk communications that are easy-to-understand and adapted to specific needs of at-risk groups. Communications should provide a limited number of messages that include specific actions for avoiding smoke exposure. Effective communications should use mixed media formats and a wide variety of dissemination strategies. There is a pressing need for more intervention research and effectiveness evaluation of risk communications about wildfire smoke exposure, and more development and dissemination of risk communications for both the general public and vulnerable populations.

Wildfire events have increased in frequency and severity across the United States in recent decades. While a growing literature has documented the effects of wildfire smoke exposure on a wide range of health and socioeconomic outcomes, little is known about its impact on consumer behavior and household demand for adaptation in healthcare. We combine a newly developed and digitized dataset on daily wildfire smoke PM2.5 concentrations across the contiguous United States from 2006 to 2019 with weekly NielsenIQ retail scanner data to quantify how wildfire smoke exposure affects retail sales of air purifiers, bottled water, cold remedies, nasal products, cough products, and nutritional products. We find a positive and statistically significant impact of wildfire smoke exposure on the retail sales of these products. Dynamic effects are evident as wildfire smoke exposure in previous weeks also increases current sales. Nonlinear effects arising from the varying intensity of wildfire smoke exposure also reveal distinct patterns of demand for adaptation. We further explore how the effects of wildfire smoke exposure vary with socio-demographic characteristics, focusing on social vulnerability and highlighting the implications of environmental justice. Our results underscore the need for proactive policies to address the increased demand for emergency supplies and healthcare products as household adaptive measures during the wildfire season, particularly targeting socioeconomically vulnerable populations who may be prone to limited access to preventive measures against wildfire smoke. [ABSTRACT FROM AUTHOR]

Quantifying the variable impacts of wildfire smoke on ozone air quality is challenging. Here we use airborne measurements from the 2018 Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE‐CAN) to parameterize emissions of reactive nitrogen (NOy) from wildfires into peroxyacetyl nitrate (PAN; 37%), NO3− (27%), and NO (36%) in a global chemistry‐climate model with 13 km spatial resolution over the contiguous US. The NOy partitioning, compared with emitting all NOy as NO, reduces model ozone bias in near‐fire smoke plumes sampled by the aircraft and enhances ozone downwind by 5–10 ppbv when Canadian smoke plumes travel to Washington, Utah, Colorado, and Texas. Using multi‐platform observations, we identify the smoke‐influenced days with daily maximum 8‐hr average (MDA8) ozone of 70–88 ppbv in Kennewick, Salt Lake City, Denver and Dallas. On these days, wildfire smoke enhanced MDA8 ozone by 5–25 ppbv, through ozone produced remotely during plume transport and locally via interactions of smoke plume with urban emissions. Plain Language Summary: Wildfires have torn across western North America over the last decade. Smoke from wildland fires in Canada can travel thousands of kilometers to US cities and reacts with urban pollution to create harmful ozone, a criteria pollutant regulated by the US Environmental Protection Agency. Accurately quantifying this impact is needed to inform US air quality policy, but is challenging due to complex physical and chemical processes. In this study, we analyze surface and airborne measurements, alongside a new variable‐resolution global chemistry‐climate model, to better understand these processes. We show that the near‐field conversion of nitrogen oxide (NOx) emissions from wildfires to peroxyacetyl nitrate (PAN) and other more oxidized forms reduces their localized impacts on ozone. PAN is the principal tropospheric reservoir for NOx radicals. When aged smoke plumes descend southward from Canada toward US cities, higher temperatures cause PAN to decompose and thus help production of ozone during smoke transport. On days when the observed ozone levels exceed the air quality limit (70 ppbv for 8‐hr average), wildfire smoke can contribute 5–25 ppbv. Key Points: Sequestration of wildfire NOx emissions in Canada as peroxyacetyl nitrate (PAN) enhances the downwind impacts on US O3 air qualityPyrogenic volatile organic compounds and PAN decomposition increase the contribution of aged Canadian smoke plumes to O3 in US citiesAccounting for these effects in a high‐resolution chemistry‐climate model improves simulation of smoke‐impacted high‐O3 events in US cities [ABSTRACT FROM AUTHOR]

The purpose of this study was to understand the experiences of agricultural workers during periods of heat and wildfire smoke exposure and to support the development and implementation of protective workplace interventions. Using community-engaged research and the Center for Disease Control (CDC) framework for policy evaluation, a qualitative descriptive study was conducted with current and former agricultural workers in Central Washington (WA). Twelve participants answered semi-structured questions via interviews or by attending a focus group. Interviews and focus groups were conducted in Spanish, recorded, transcribed, and translated into English; one interview was conducted in English. Using Braun and Clarke's Reflexive Thematic Analysis, five themes were identified among workers from various worksites: 1) Extreme weather and working conditions are becoming increasingly hazardous to worker health, 2) Employers and supervisors lack training and education on current labor laws, and health and safety rules, 3) Employers and supervisors use intimidation and retaliation to ensure productivity and to evoke feelings of replaceability among workers, 4) Workers do not trust regulatory agencies to enforce rules or hold employers accountable, 5) Solutions to climate-driven problems in the agricultural industry need to value worker health and safety, not just productivity. Participants reported experiencing adverse health symptoms related to heat and smoke exposure at work. Workers proposed solutions including improving education, training, and communication, and increased enforcement of existing and forthcoming occupational health and safety rules. The agricultural workforce is essential for ensuring a robust food supply and is facing extreme weather events due to climate change. Western states impacted by wildfires and heat are working to develop and implement occupational health and safety rules. Developing effective policies and interventions inclusive of worker perspectives is critical to adapt to a changing climate, retain a stable workforce and promote optimal health. [ABSTRACT FROM AUTHOR]

Wildfire activity is increasing around the world, concurrent with climate change, and mitigation strategies for protecting vulnerable populations are desperately needed. Because inhaled particles are deleterious to respiratory health, particularly among older adults with co-morbidities, we engaged maintenance personnel working in long term care facilities located in the Western US. Our objective was to identify opportunities to build resilience during wildfire smoke events. We implemented a virtual workshop that addressed wildfire smoke health impacts as well as strategies to assess and maintain indoor air quality. A total of 24 maintenance personnel attended the virtual workshop and 14 participated in a quantitative survey. Workshop attendees found value in the material and there was enthusiasm for educational resources and enhancing indoor air quality. Four months later, four maintenance staff participated in a follow-up interview. Our qualitative assessment revealed the following themes: awareness and prioritization, application of knowledge, barriers, and educational resources. Access to real-time actionable air quality data was a consistent feature across these themes. Maintenance personnel could play a key role in a facility's ability to prepare for and respond to wildfire smoke events, and this study highlights potential challenges and opportunities to involving them in resilience building strategies. [ABSTRACT FROM AUTHOR]

Wildfires are increasing across the USA. While smoke events affect human exposure and air quality, wildfire smoke effects on ecosystem‐atmosphere interactions are poorly understood. We investigate smoke effects on biogenic volatile organic compound (VOC) emissions and photosynthesis for ponderosa pines. During several wildfire smoke events, we observed photosynthetic reduction with evidence for stomatal plugging and changes in leaf‐level uptake and emission of both biogenic and wildfire VOCs. During intense smoke events, photosynthesis and VOC emissions were almost entirely suppressed, but increased dramatically upon stomatal opening. We propose four types of VOC responses to this burst in stomatal opening: post‐burst emissions, pulsed emissions, surge emissions, and post‐burst uptake. Our observations suggest that wildfire smoke can affect plant physiology and leaf‐atmosphere gas exchange. Plain Language Summary: Wildfires are becoming more prevalent in the United States. Wildfire smoke affects human health and air quality, but we know little about how smoke interacts with plants, or the subsequent feedback with the atmosphere. We present results from a field experiment during which smoke repeatedly spread across a pine forest. We measured smoke‐induced changes in plant physiology (namely photosynthesis) and a suite of chemical emissions. During prolonged periods of intense smoke, we found that both photosynthesis and leaf emissions of chemical compounds decreased. When we induced photosynthesis, we observed a burst of different chemicals and identified several different pathways for these chemical releases. Further analyses suggest that smoke intensity and exposure may change the known relationship between emissions and temperature. Key Points: Wildfire smoke interacts with stomates and leaf surfaces, suppressing photosynthesis and stomatal conductanceIntense smoke can alter emissions and uptake of biogenic and other volatile organic compounds through three mechanismsThe effects of wildfires on photosynthetic capacity and leaf emissions appear proportional to the intensity and duration of smoke events [ABSTRACT FROM AUTHOR]

BackgroundWildfire smoke is responsible for around 20% of all particulate emissions in the U.S. and affects millions of people worldwide. Children are especially vulnerable, as ambient air pollution exposure during early childhood is associated with reduced lung function. Most studies, however, have focused on the short-term impacts of wildfire smoke exposures. We aimed to identify long-term baseline epigenetic changes associated with early-life exposure to wildfire smoke. We collected nasal epithelium samples for whole genome bisulfite sequencing (WGBS) from two groups of adult female rhesus macaques: one group born just before the 2008 California wildfire season and exposed to wildfire smoke during early-life (n = 8), and the other group born in 2009 with no wildfire smoke exposure during early-life (n = 14). RNA-sequencing was also performed on a subset of these samples.ResultsWe identified 3370 differentially methylated regions (DMRs) (difference in methylation ≥ 5%, empirical p

Sub-micron particles are ubiquitous in the indoor environment, especially during wildfire smoke episodes, and have a higher impact on human health than larger particles. Conventional fibrous air filters installed in heating, ventilation, and air conditioning (HVAC) systems play an important role in controlling indoor air quality by removing various air pollutants, including particulate matter (PM). However, it is evident that the removal efficiency of wildfire smoke PM and its effect on filter performance is significantly under-studied. This study delves into the size-specific removal efficiency of pine needle smoke, a representative of wildfire smoke and emissions. We test an array of filter media with minimum efficiency reporting values (MERV) spanning 11–15. Both size-resolved particle number concentrations and mass concentrations were measured using an Optical Particle Sizer (OPS, TSI, Inc.) and a Scanning Mobility Particle Sizer (SMPS, TSI, Inc.). Furthermore, we characterize the filter media morphology and smoke particles deposited on filter fibers using Scanning Electron Microscopy (SEM) to gain insights into the interaction dynamics of these particles. Our findings add to the comprehension of the relationship between MERV designations and smoke removal efficiency. Such insight can inform standards and guidelines and equip decision-makers with the knowledge needed to initiate measures for mitigating the impact of air pollution, specifically on the indoor environment. [ABSTRACT FROM AUTHOR]

There have been few empirical studies of the sensitivity of birds to the effect of air pollutants. In late 2019 and early 2020 the Australian Capital Territory (ACT) and much of south-eastern Australia were affected by extreme wildfire events and smoke extended to surrounding areas. Prior to this event, GPS transmitters had been fitted to a sample of Little Eagles Hieraaetus morphnoides in the ACT as part of a study of their movement behaviour. Three of these birds carried transmitters in the breeding season during the fires and in the previous breeding season. This offered opportunistic analysis of data from both periods to test for effects of smoke on the birds' flight behaviour. The effects of particulate matter in the air of ≤2.5 microns in diameter (PM2.5) and covariates on flight status were investigated with a binomial generalised linear model with logistic link. The birds were more likely to fly when there were low levels of PM2.5 and the odds of flying decreased as density of PM2.5 increased at a rate of 0.202% per ug/m3. None of the sample birds died during or after smoke exposure, although their respiratory system might have been affected. [ABSTRACT FROM AUTHOR]

Wildfire smoke is an increasing environmental health threat to which children are particularly vulnerable, for both physiologic and behavioral reasons. To address the need for improved public health messaging this review summarizes current knowledge and knowledge gaps in the health effects of wildfire smoke in children, as well as tools for public health response aimed at children, including consideration of low-cost sensor data, respirators, and exposures in school environments. There is an established literature of health effects in children from components of ambient air pollution, which are also present in wildfire smoke, and an emerging literature on the effects of wildfire smoke, particularly for respiratory outcomes. Low-cost particulate sensors demonstrate the spatial variability of pollution, including wildfire smoke, where children live and play. Surgical masks and respirators can provide limited protection for children during wildfire events, with expected decreases of roughly 20%  and 80% for surgical masks and N95 respirators, respectively. Schools should improve filtration to reduce exposure of our nation's children to smoke during wildfire events. The evidence base described may help clinical and public health authorities provide accurate information to families to improve their decision making.

Wildfire smoke exposure is a growing global health threat. The acute respiratory health effects of wildfire smoke exposure are well-established, but the potential chronic effects are still being investigated. It is important to prioritize intervention for susceptible and vulnerable populations to achieve health equity. Effective interventions to mitigate personal exposure to wildfire smoke require coordinated efforts and sufficient resources, responsive to individual needs and community context. Urgent investigation is needed to understand the long-term effects of wildfire smoke exposure and its role in the development of respiratory and cardiovascular diseases. Reducing global fossil fuel emissions and optimizing forest management are crucial, but in the meantime, individuals are encouraged to monitor air quality and take measures to limit exposure. Communication and education on wildfire smoke mitigation should be diverse, consistent, and tailored to individual needs and community context. Efforts should be made to engage and support vulnerable populations, reduce environmental health disparities, and promote health equity. [Extracted from the article]

Air pollution poses well-established risks to physical health, but little is known about its effects on mental health. We study the relationship between wildfire smoke exposure and suicide risk in the United States in 2007 to 2019 using data on all deaths by suicide and satellite-based measures of wildfire smoke and ambient fine particulate matter (PM2.5) concentrations. We identify the causal effects of wildfire smoke pollution on suicide by relating year-over-year fluctuations in county-level monthly smoke exposure to fluctuations in suicide rates and compare the effects across local areas and demographic groups that differ considerably in their baseline suicide risk. In rural counties, an additional day of smoke increases monthly mean PM2.5 by 0.41 μg/m³ and suicide deaths by 0.11 per million residents, such that a 1-μg/m³ (13%) increase in monthly wildfire-derived fine particulate matter leads to 0.27 additional suicide deaths per million residents (a 2.0% increase). These effects are concentrated among demographic groups with both high baseline suicide risk and high exposure to outdoor air: men, working-age adults, non-Hispanic Whites, and adults with no college education. By contrast, we find no evidence that smoke pollution increases suicide risk among any urban demographic group. This study provides large-scale evidence that air pollution elevates the risk of suicide, disproportionately so among rural populations. [ABSTRACT FROM AUTHOR]

As wildfire risk is projected to increase across most of the world, exposure to wildfire smoke is a growing global health issue. Clean air centers (CACs), public buildings designated to provide improved air quality to the public during a wildfire smoke event, have emerged as a community-oriented public health response to smoke. Some experts see CACs as the most effective way to reduce population exposure to wildfire smoke. Yet how and why smoke-vulnerable groups utilize CACs, as well as how CACs may be improved to meet their needs, is not well understood. Here, we explore these questions through exploratory interviews with two groups of stakeholders in California CAC development: practitioners and members of a community vulnerable to wildfire smoke. Our findings suggest that a gap remains between California's CACs and the needs of vulnerable groups. By comparing community and practitioner perspectives, we identify opportunities to close this gap. [ABSTRACT FROM AUTHOR]

Copyright of Fire Ecology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Smoke from wildland fires has been shown to produce neuroinflammation in preclinical models, characterized by neural infiltrations of neutrophils and monocytes, as well as altered neurovascular endothelial phenotypes. To address the longevity of such outcomes, the present study examined the temporal dynamics of neuroinflammation and metabolomics after inhalation exposures from biomass-derived smoke. 2-month-old female C57BL/6 J mice were exposed to wood smoke every other day for 2 weeks at an average exposure concentration of 0.5 mg/m3. Subsequent serial euthanasia occurred at 1-, 3-, 7-, 14-, and 28-day post-exposure. Flow cytometry of right hemispheres revealed two endothelial populations of CD31Hi and CD31Med expressors, with wood smoke inhalation causing an increased proportion of CD31Hi. These populations of CD31Hi and CD31Med were associated with an anti-inflammatory and pro-inflammatory response, respectively, and their inflammatory profiles were largely resolved by the 28-day mark. However, activated microglial populations (CD11b+/CD45low) remained higher in wood smoke-exposed mice than controls at day 28. Infiltrating neutrophil populations decreased to levels below controls by day 28. However, the MHC-II expression of the peripheral immune infiltrate remained high, and the population of neutrophils retained an increased expression of CD45, Ly6C, and MHC-II. Utilizing an unbiased approach examining the metabolomic alterations, we observed notable hippocampal perturbations in neurotransmitter and signaling molecules, such as glutamate, quinolinic acid, and 5-α-dihydroprogesterone. Utilizing a targeted panel designed to explore the aging-associated NAD+ metabolic pathway, wood smoke exposure drove fluctuations and compensations across the 28-day time course, ending with decreased hippocampal NAD+ abundance on day 28. Summarily, these results indicate a highly dynamic neuroinflammatory environment, with potential resolution extending past 28 days, the implications of which may include long-term behavioral changes, systemic and neurological sequalae directly associated with wildfire smoke exposure. [ABSTRACT FROM AUTHOR]

Wildfire smoke is associated with short-term respiratory outcomes including asthma exacerbation in children. As investigations into developmental wildfire smoke exposure on children's longer-term respiratory health are sparse, we investigated associations between developmental wildfire smoke exposure and first use of respiratory medications. Prescription claims from IBM MarketScan Commercial Claims and Encounters database were linked with wildfire smoke plume data from NASA satellites based on Metropolitan Statistical Area (MSA). A retrospective cohort of live infants (2010–2016) born into MSAs in six western states (U.S.A.), having prescription insurance, and whose birthdate was estimable from claims data was constructed (N = 184,703); of these, gestational age was estimated for 113,154 infants. The residential MSA, gestational age, and birthdate were used to estimate average weekly smoke exposure days (smoke-day) for each developmental period: three trimesters, and two sequential 12-week periods post-birth. Medications treating respiratory tract inflammation were classified using active ingredient and mode of administration into three categories:: 'upper respiratory', 'lower respiratory', 'systemic anti-inflammatory'. To evaluate associations between wildfire smoke exposure and medication usage, Cox models associating smoke-days with first observed prescription of each medication category were adjusted for infant sex, birth-season, and birthyear with a random intercept for MSA. Smoke exposure during postnatal periods was associated with earlier first use of upper respiratory medications (1–12 weeks: hazard ratio (HR) = 1.094 per 1-day increase in average weekly smoke-day, 95%CI: (1.005,1.191); 13–24 weeks: HR = 1.108, 95%CI: (1.016,1.209)). Protective associations were observed during gestational windows for both lower respiratory and systemic anti-inflammatory medications; it is possible that these associations may be a consequence of live-birth bias. These findings suggest wildfire smoke exposure during early postnatal developmental periods impact subsequent early life respiratory health. [ABSTRACT FROM AUTHOR]

Wildfire poses a significant threat and is considered a severe natural disaster, which endangers forest resources, wildlife, and human livelihoods. In recent times, there has been an increase in the number of wildfire incidents, and both human involvement with nature and the impacts of global warming play major roles in this. The rapid identification of fire starting from early smoke can be crucial in combating this issue, as it allows firefighters to respond quickly to the fire and prevent it from spreading. As a result, we proposed a refined version of the YOLOv7 model for detecting smoke from forest fires. To begin, we compiled a collection of 6500 UAV pictures of smoke from forest fires. To further enhance YOLOv7's feature extraction capabilities, we incorporated the CBAM attention mechanism. Then, we added an SPPF+ layer to the network's backbone to better concentrate smaller wildfire smoke regions. Finally, decoupled heads were introduced into the YOLOv7 model to extract useful information from an array of data. A BiFPN was used to accelerate multi-scale feature fusion and acquire more specific features. Learning weights were introduced in the BiFPN so that the network can prioritize the most significantly affecting characteristic mapping of the result characteristics. The testing findings on our forest fire smoke dataset revealed that the proposed approach successfully detected forest fire smoke with an AP50 of 86.4%, 3.9% higher than previous single- and multiple-stage object detectors. [ABSTRACT FROM AUTHOR]

Smoke from wildfires or burning biomass directly affects air quality and weather through modulating cloud microphysics and radiation. A simple wildfire emission coupling of black carbon (BC) and organic carbon (OC) with microphysics was implemented using the Weather Research and Forecasting model's fire module. A set of large‐eddy simulations inspired by unique surface and upper atmospheric observations from the 2021 Santa Coloma de Queralt Fire (Spain) were conducted to investigate the influence of background conditions and interactions between atmospheric and fire processes such as fire smoke, ambient moisture, and latent heat release on the formation and evolution of pyroconvective clouds. While the microphysical impact of BC and OC emissions on the dynamics of fire behavior is minimal on short time scales (<6 hr), their presence increased the cloud water content and decreased the rain rates in our case study. In our case study, atmospheric moisture played an important role in the formation and development of pyroconvective clouds, which in turn enhanced the surface winds (8%) and fire spread rate (25%). The influence of fuel moisture on the pyroconvective cloud formation is smaller when compared with the atmospheric moisture content. A better representation of cloud processes can improve the mesoscale forecasts, which is important for better fire behavior modeling. Plain Language Summary: Pyroconvective clouds are formed directly as a result of wildland fires. They are influential on fire behavior, hard to predict, and impose hazardous conditions on the first responders and people in the area. Various environmental factors, such as atmospheric moisture, fuel moisture, fire intensity, and smoke, impact the formation and evolution of these clouds. Smoke from wildfires or burning biomass affects air quality and weather directly. The impact of smoke on the weather is either through radiative effects or cloud formation. Cloud water condensation can occur on the smoke particles where new cloud drops form. These processes are not currently represented in WRF‐Fire, a model simulating weather and wildfire evolution and interactions. We have implemented a simple emission model to represent the effect of smoke on the clouds. We investigated the impact of atmospheric and fuel moisture, as well as the smoke, on the pyroconvective clouds. We rely on unique in situ measurements to design our simulations and interpret the results. The availability of atmospheric moisture is essential for the formation of pyroconvective cloud. When a pyroconvective cloud forms, it creates faster winds, which, in turn cause faster fire propagation. Key Points: A simple coupling of black and organic carbon emissions from wildfires to cloud microphysicsEnvironmental atmospheric moisture has a more significant influence than surface moisture release on the pyroconvective cloud formationIn our case study, the formation of pyroconvective clouds increased the surface winds and fire spread rate by 8% and 25%, respectively [ABSTRACT FROM AUTHOR]

PurpleAir particulate matter (PM) sensors are increasingly used in the United States and other countries for real-time air quality information, particularly during wildfire smoke episodes. Uncorrected PurpleAir data can be biased and may exhibit a nonlinear response at extreme smoke concentrations (>300 µg/m3). This bias and nonlinearity result in a disagreement with the traditional ambient monitoring network, leading to the public's confusion during smoke episodes. These sensors must be evaluated during smoke-impacted times and then corrected for bias, to ensure that accurate data are reported. The nearby public PurpleAir sensor and monitor pairs were identified during the summer of 2020 and were used to supplement the data from collocated pairs to develop an extended U.S.-wide correction for high concentrations. We evaluated several correction schemes to identify an optimal correction, using the previously developed U.S.-wide correction, up to 300 µg/m3, transitioning to a quadradic fit above 400 µg/m3. The correction reduces the bias at each air quality index (AQI) breakpoint; most ambient collocations that were studied met the Environmental Protection Agency's (EPA) performance targets (twelve of the thirteen ambient sensors met the EPA's targets) and some smoke-impacted sites (5 out of 15 met the EPA's performance targets in terms of the 1-h averages). This correction can also be used to improve the comparability of PurpleAir sensor data with regulatory-grade monitors when they are collectively analyzed or shown together on public information websites; the methods developed in this paper can also be used to correct future air-sensor types. The PurpleAir network is already filling in spatial and temporal gaps in the regulatory monitoring network and providing valuable air-quality information during smoke episodes. [ABSTRACT FROM AUTHOR]

Background: Smoke from wildfires is a growing public health risk due to the enormous amount of smoke-related pollution that is produced and can travel thousands of kilometers from its source. While many studies have documented the physical health harms of wildfire smoke, less is known about the effects on mental health and well-being. Understanding the effects of wildfire smoke on mental health and well-being is crucial as the world enters a time in which wildfire smoke events become more frequent and severe. We conducted a scoping review of the existing information on wildfire smoke's impact on mental health and well-being and developed a model for understanding the pathways in which wildfire smoke may contribute to mental health distress.Methods: We conducted searches using PubMed, Medline, Embase, Google, Scopus, and ProQuest for 1990-2022. These searches yielded 200 articles. Sixteen publications met inclusion criteria following screening and eligibility assessment. Three more publications from the bibliographies of these articles were included for a total of 19 publications.Results: Our review suggests that exposure to wildfire smoke may have mental health impacts, particularly in episodes of chronic and persistent smoke events, but the evidence is inconsistent and limited. Qualitative studies disclose a wider range of impacts across multiple mental health and well-being domains. The potential pathways connecting wildfire smoke with mental health and well-being operate at multiple interacting levels including individual, social and community networks, living and working conditions, and ecological levels.Conclusions: Priorities for future research include: 1) applying more rigorous methods; 2) differentiating between mental illness and emotional well-being; 3) studying chronic, persistent or repeated smoke events; 4) identifying the contextual factors that set the stage for mental health and well-being effects, and 5) identifying the causal processes that link wildfire smoke to mental health and well-being effects. The pathways model can serve as a basis for further research and knowledge synthesis on this topic. Also, it helps public health, community mental health, and emergency management practitioners mitigate the mental health and well-being harms of wildfire smoke. [ABSTRACT FROM AUTHOR]

During wildfire smoke events public health agencies release advisories to stay indoors, close doors and windows, and operate a portable air cleaner (PAC). The do‐it‐yourself (DIY) air cleaner consisting of a box fan and a furnace filter is a widely used low‐cost alternative to commercial PACs because of its increased accessibility. In this study, we evaluate the clean air delivery rate (CADR) of different DIY air cleaner designs for reducing simulated wildfire smoke and identify operating parameters that may impact their performance and use. The simplest formulation of a DIY air cleaner (box fan with taped on minimum effectiveness reporting value – [MERV] 13 furnace filter) had a CADR of 111.2 ± 1.3 ft3/min (CFM). Increasing the fan flow by changing the fan type, increasing the fan setting, or reducing the pressure drop across the filtering surface increased the CADR. Large increases in CADR could be obtained by using a shroud (40%), using a 4″ thick filter (123%) using two filters in a wedge shape (137%), or using four filters in a Corsi‐Rosenthal (CR) box design (261%). The CADR was greatly reduced with filters heavily loaded with smoke, pointing to the need for frequent filter changes during smoke events. [ABSTRACT FROM AUTHOR]

Simple Summary: With increasing wildfires in the western US and around the world, it is important to take stock of impacts to humans as well as animals. Fires create smoke, and exposure to wildfire particles is known to negatively impact health. Therefore, we asked if smoke might get into buildings where animal research takes place. Our one-month study provides evidence that smoke does get inside an animal facility and levels can exceed ambient air quality standards that are set to protect public health. More work is needed to establish the impact that indoor smoke exposure might have on research animals, but we suggest these data warrant consideration for air quality monitoring and planning within animal facilities at risk for outdoor smoke events. Wildfire events are increasing across the globe. The smoke generated as a result of this changing fire landscape is potentially more toxic than air pollution from other ambient sources, according to recent studies. This is especially concerning for populations of humans or animals that live downwind of areas that burn frequently, given that ambient exposure to wildfire smoke cannot be easily eliminated. We hypothesized that a significant indoor air pollution risk existed for laboratory animal facilities located proximal to fire-prone areas. Here, we measured real time continuous outdoor and indoor air quality for 28 days at a laboratory animal facility located in the Rocky Mountain region. We demonstrated that during a wildfire event, the indoor air quality of this animal facility is influenced by ambient smoke events. The daily average indoor fine particulate matter value in an animal room exceeded the Environmental Protection Agency's ambient annual standard 14% of the time and exceeded the World Health Organization's ambient annual guideline 71% of the time. We further show that specialized cage filtration systems are capable of mitigating air pollution penetrance and could improve an animal's microenvironment. The potential effects for laboratory animal physiology that occur in response to the exposure levels and durations measured in this study remain to be determined; yet, even acute wildfire exposure events have been previously correlated with significant differences in gene regulatory and metabolic processes in vivo. We believe these findings warrant consideration for indoor laboratory animal facility air quality monitoring and development of smoke exposure prevention and response protocols, especially among facilities located downwind of fire-prone landscapes. [ABSTRACT FROM AUTHOR]

Governments monitor air quality for regulatory purposes and, more recently, to provide information so individuals can act to lower their exposure to air pollution. Recent developments in low-cost technologies have also led to private adoption of air-quality monitors that produce publicly accessible air-quality readings. We study the adoption of these private air-quality monitors. We find that shocks to air pollution from wildfire result in substantial adoption. We also find that additional private monitors are concentrated in white, wealthy, and politically liberal neighborhoods. In contrast, there is no evidence that pollution shocks lead to higher adoption in neighborhoods with lower pre-existing access to monitors, higher long-run pollution, or those with more vulnerable populations. Private provision increases inequality in the availability of localized air-quality information. [ABSTRACT FROM AUTHOR]

Adverse weather events significantly impact the operations of urban transportation systems and change human travel behaviors. Over the decades, wildfires have emerged as a pressing concern due to their increased frequency and intensity, yet the relationship between wildfire smoke and public transportation usage remains largely unexplored. Leveraging high-resolution daily wildfire-driven PM 2.5 concentration estimates and station-level Metrorail ridership data in the Washington Metropolitan Area spanning 2012–2019, we examine the effects of wildfire smoke exposure on Metrorail usage. We find that wildfire smoke exposure results in a 0.8% increase in Metrorail ridership on weekdays and a more pronounced 3.7% rise on weekends. Additionally, we show a stronger response in Metrorail ridership to wildfire smoke during off-peak hours compared to peak hours, with the most substantial increase observed during the winter. Our heterogeneity analysis further suggests that a lack of vehicle ownership and higher reliance on walking and public transportation are key factors leading to increased Metrorail ridership. Collectively, these results highlight the need for proactive service adjustments and effective communication strategies to accommodate the potential shifts in human travel behaviors and Metrorail ridership on days exposed to wildfire smoke. [ABSTRACT FROM AUTHOR]

The impacts of wildfire smoke on lake habitats remains unclear. We determined the metabolic response to smoke in the epi‐pelagic and two littoral habitats in Castle Lake, California. We compared light regime, gross primary production, ecosystem respiration, and net ecosystem production in years with and without smoke. During the smoke period incident ultraviolet‐B (UV‐B) radiation and photosynthetically active radiation (PAR) decreased by 53% and 28%, respectively, while the water column extinction coefficient of UV‐B and PAR increased by 20% and 18% respectively. Epi‐pelagic productivity increased during smoke cover because of decreased solar inputs. PAR values remained sufficient to saturate productivity, suggesting observed differences were primarily the result of changes in UV‐B. Littoral‐benthic productivity did not change, possibly reflecting adaptation to high‐intensity UV‐B light in these habitats. Our results highlight the importance of understanding how prolonged wildfire smoke alters the amount of energy produced from specific habitats in lakes. Plain Language Summary: Large wildfires are increasing worldwide, but the impacts of wildfire smoke on lakes are unknown. We determined how photosynthetic activity and organism's respiration respond to smoke in the offshore and nearshore habitats in a mountain lake. Smoke limited the damage to algae caused by ultraviolet‐B radiation, resulting in increased offshore photosynthesis. Photosynthesis in the nearshore habitat did not change during smoke cover, possibly because organisms in shallow habitats have adapted to the higher intensity of damaging ultraviolet‐B radiation. Our results highlight the importance of understanding how prolonged smoke conditions can alter lakes' energy flows and food webs. Key Points: Wildfire smoke reduced ultraviolet‐B and photosynthetically active radiationLake habitats respond differently to changes in light from smoke, pelagic primary production increased with no change to littoral metabolismSmoke alters energy flows with implications for food web structure in lakes [ABSTRACT FROM AUTHOR]

Background: Extreme, prolonged wildfire smoke (WFS) events are becoming increasingly frequent phenomena across the Western United States. Rural communities, dependent on contributions of nature to people's quality of life, are particularly hard hit. While prior research has explored the physical health impacts of WFS exposure, little work has been done to assess WFS impacts on mental health and wellbeing, or potential adaptation solutions.Methods: Using qualitative methods, we explore the mental health and wellbeing impacts experienced by community members in a rural Washington State community that has been particularly hard hit by WFS in recent years, as well as individual, family, and community adaptation solutions. We conducted focus groups with residents and key informant interviews with local health and social service providers.Results: Participants identified a variety of negative mental health and wellbeing impacts of WFS events, including heightened anxiety, depression, isolation, and a lack of motivation, as well as physical health impacts (e.g., respiratory issues and lack of exercise). Both positive and negative economic and social impacts, as well as temporary or permanent relocation impacts, were also described. The impacts were not equitably distributed; differential experiences based on income level, outdoor occupations, age (child or elderly), preexisting health conditions, housing status, and social isolation were described as making some residents more vulnerable to WFS-induced physical and mental health and wellbeing challenges than others. Proposed solutions included stress reduction (e.g., meditation and relaxation lessons), increased distribution of air filters, development of community clean air spaces, enhancing community response capacity, hosting social gatherings, increasing education, expanding and coordination risk communications, and identifying opportunities for volunteering. Findings were incorporated into a pamphlet for community distribution. We present a template version herein for adaptation and use in other communities.Conclusions: Wildfire smoke events present significant mental health and wellbeing impacts for rural communities. Community-led solutions that promote stress reduction, physical protection, and community cohesion have the opportunity to bolster resilience amid this growing public health crisis. [ABSTRACT FROM AUTHOR]

As anthropogenic emissions continue to decline and emissions from landscape (wild, prescribed, and agricultural) fires increase across the coming century, the relative importance of landscape‐fire smoke on air quality and health in the United States (US) will increase. Landscape fires are a large source of fine particulate matter (PM2.5), which has known negative impacts on human health. The seasonal and spatial distribution, particle composition, and co‐emitted species in landscape‐fire emissions are different from anthropogenic sources of PM2.5. The implications of landscape‐fire emissions on the sub‐national temporal and spatial distribution of health events and the relative health importance of specific pollutants within smoke are not well understood. We use a health impact assessment with observation‐based smoke PM2.5 to determine the sub‐national distribution of mortality and the sub‐national and sub‐annual distribution of asthma morbidity attributable to US smoke PM2.5 from 2006 to 2018. We estimate disability‐adjusted life years (DALYs) for PM2.5 and 18 gas‐phase hazardous air pollutants (HAPs) in smoke. Although the majority of large landscape fires occur in the western US, we find the majority of mortality (74%) and asthma morbidity (on average 75% across 2006–2018) attributable to smoke PM2.5 occurs outside the West, due to higher population density in the East. Across the US, smoke‐attributable asthma morbidity predominantly occurs in spring and summer. The number of DALYs associated with smoke PM2.5 is approximately three orders of magnitude higher than DALYs associated with gas‐phase smoke HAPs. Our results indicate awareness and mitigation of landscape‐fire smoke exposure is important across the US. Plain Language Summary: The pollutants from landscape (wild, prescribed, and agricultural) fires are expected to have an increasing impact on air quality and health in the United States (US) across the current century. The implications of landscape‐fire smoke on the regional and seasonal distribution of health events and the relative health importance of specific pollutants within smoke are not well understood. In the present study, we assess the seasonal and regional distribution of the health impacts from US smoke exposure from 2006 to 2018. We also estimate the long‐term health impacts for both fine particles (PM2.5) and gas‐phase hazardous air pollutants (HAPs) in smoke. Although the majority of large landscape fires occur in the western US, we find the majority of deaths (74%) and asthma emergency department visits and hospital admissions (on average 75% across 2006–2018) attributable to smoke occur outside the West. Across the US, smoke‐attributable asthma emergency department visits predominantly occur in spring and summer. The long‐term health impacts associated with smoke PM2.5 are much higher than the estimated long‐term health impacts of gas‐phase smoke HAPs. Our results indicate awareness and mitigation of landscape‐fire smoke exposure is important across the US, not just in regions in proximity to large wildfires. Key Points: While the majority of large fires occur in the United States (US) West, a majority of smoke‐attributable US mortality and morbidity occur east of ∼100 degWA higher percent of mortality and morbidity is attributable to smoke in high fire‐impacted northwestern states, relative to other US statesDisability‐adjusted life years attributable to fine particles in smoke are much higher than that from gas‐phase hazardous air pollutants [ABSTRACT FROM AUTHOR]

We analyze new aerosol products from NASA satellite retrievals over the western USA during August 2013, with special attention to locally generated wildfire smoke and downwind plume structures. Aerosol optical depth (AOD) at 550 nm from MODerate Resolution Imaging Spectroradiometer (MODIS) (Terra and Aqua Collections 6 and 6.1) and Visible Infrared Imaging Radiometer Suite (VIIRS) Deep Blue (DB) and MODIS (Terra and Aqua) Multi‐Angle Implementation of Atmospheric Correction (MAIAC) retrievals are evaluated against ground‐based AErosol RObotic NETwork (AERONET) observations. We find a significant improvement in correlation with AERONET and other metrics in the latest DB AOD (MODIS C6.1 r2 = 0.75, VIIRS r2 = 0.79) compared to MODIS C6 (r2 = 0.62). In general, MAIAC (r2 = 0.84) and DB (MODIS C6.1 and VIIRS) present similar statistical evaluation metrics for the western USA and are useful tools to characterize aerosol loading associated with wildfire smoke. We also evaluate three novel NASA MODIS plume injection height (PIH) products, one from MAIAC and two from the Aerosol Single scattering albedo and layer Height Estimation (ASHE) (MODIS and VIIRS) algorithm. Both Terra and Aqua MAIAC PIHs statistically agree with ground‐based and satellite lidar observations near the fire source, as do ASHE, although the latter is sensitive to assumptions about aerosol absorption properties. We introduce a first‐order approximation Smoke Height Boundary Layer Ratio (SHBLR) to qualitatively distinguish between aerosol pollution within the planetary boundary layer and the free troposphere. We summarize the scope, limitations, and suggestions for scientific applications of surface level aerosol concentrations specific to wildfire emissions and smoke plumes using these novel NASA MODIS and VIIRS aerosol products. Key Points: Aerosol optical depth and plume injection height products from new collections of Moderate resolution imaging spectroradiometer and Visible Infrared Imaging Radiometer Suite demonstrate improved capabilities for smoke eventsNew Smoke Height Boundary Layer Ratio indicates when wildfire smoke aerosols are likely to be confined within the planetary boundary layerHeterogeneous vertical aerosol profiles were found downwind of wildfires induced by mountainous terrain and complex boundary layer physics [ABSTRACT FROM AUTHOR]

In recent years, wildland fires have occurred more frequently and with increased intensity in many fire-prone areas. In addition to the direct life and economic losses attributable to wildfires, the emitted smoke is a major contributor to ambient air pollution, leading to significant public health impacts. Wildfire smoke is a complex mixture of particulate matter (PM), gases such as carbon monoxide, nitrogen oxide, and volatile and semi-volatile organic compounds. PM from wildfire smoke has a high content of elemental carbon and organic carbon, with lesser amounts of metal compounds. Epidemiological studies have consistently found an association between exposure to wildfire smoke (typically monitored as the PM concentration) and increased respiratory morbidity and mortality. However, previous reviews of the health effects of wildfire smoke exposure have not established a conclusive link between wildfire smoke exposure and adverse cardiovascular effects. In this review, we systematically evaluate published epidemiological observations, controlled clinical exposure studies, and toxicological studies focusing on evidence of wildfire smoke exposure and cardiovascular effects, and identify knowledge gaps. Improving exposure assessment and identifying sensitive cardiovascular endpoints will serve to better understand the association between exposure to wildfire smoke and cardiovascular effects and the mechanisms involved. Similarly, filling the knowledge gaps identified in this review will better define adverse cardiovascular health effects of exposure to wildfire smoke, thus informing risk assessments and potentially leading to the development of targeted interventional strategies to mitigate the health impacts of wildfire smoke. [ABSTRACT FROM AUTHOR]

Biomass burning is a source of fine particulate matter (PM2.5) air pollution, which adversely impacts human health. However, quantifying the health effects from biomass burning PM2.5 is difficult. Monitoring networks generally lack the spatial density needed to capture the heterogeneity of biomass burning smoke. Satellite aerosol optical depth (AOD) can be used to fill spatial gaps but does not distinguish surface‐level aerosols. Plume height (PH) observations may provide constraints on the vertical distribution of smoke and its impact on surface concentrations. We assessed PH characteristics from Multi‐Angle Implementation of Atmospheric Correction (MAIAC) and evaluated its correlation with colocated PM2.5 and AOD measurements. PH is generally highest over the western United States. The ratio PM2.5:AOD generally decreases with increasing PH:PBLH (planetary boundary layer height), showing that PH has the potential to refine surface PM2.5 estimates for collections of smoke events. Plain Language Summary: Smoke from wildland and agricultural fires can rise high into the air or remain near the ground. This smoke height plays a major role in dictating the air quality of places downwind of fires, although these heights have been challenging to predict. Measurements from satellites are now routinely used to evaluate surface air quality. However, the satellite products commonly used in surface air quality analysis do not distinguish lofted smoke from surface smoke, leading to uncertainties in surface air quality during smoke events. We use a recently developed satellite product of smoke height to determine if these smoke‐height measurements can aid in surface air quality estimates. We also investigate how smoke plumes behave differently across the United States by counting the number of high‐altitude smoke observations over each state. Key Points: Satellite‐retrieved smoke plume heights have the potential to constrain surface particulate concentrations during biomass burning eventsPlume height is positively correlated with aerosol optical depthThe ratio of surface particulate matter and aerosol optical depth decreases with the increasing ratio of plume to boundary layer heights [ABSTRACT FROM AUTHOR]

Woodsmoke poses a significant health risk as a growing component of ambient air pollution in the United States. While there is a long history of association between woodsmoke exposure and diseases of the respiratory, circulatory, and cardiovascular systems, recent evidence has linked woodsmoke exposure to cognitive dysfunction, including Alzheimer's disease dementia. Alzheimer's disease is a progressive neurodegenerative disorder with largely idiopathic origins and no known cure. Here, we explore the growing body of literature which relates woodsmoke-generated and ambient air pollution particulate matter exposure to Alzheimer's disease (AD) onset or exacerbation, in the context of an inflammation-centric view of AD. Epigenetic modifications, specifically changes in DNA methylation patterns, are well documented following woodsmoke exposure and have been shown to influence disease-favoring inflammatory cascades, induce oxidative stress, and modulate the immune response in vitro, in vivo, and in humans following exposure to air pollution. Though the current status of the literature does not allow us to draw definitive conclusions linking these events, this review highlights the need for additional work to fill gaps in our understanding of the directionality, causality, and susceptibility throughout the life course. [ABSTRACT FROM AUTHOR]