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BackgroundAs atmospheric greenhouse gas concentrations continue to rise, temperature and humidity will increase further, causing potentially dire increases in human heat stress. On physiological and biophysical grounds, exposure to higher levels of humidity should worsen heat stress by decreasing sweat evaporation. However, population-scale epidemiological studies of heat exposure and response often do not detect associations between high levels of humidity and heat-related mortality or morbidity. These divergent, disciplinary views regarding the role of humidity in heat-related health risks limit confidence in selecting which interventions are effective in reducing health impacts and in projecting future heat-related health risks.ObjectivesVia our multidisciplinary perspective we seek to a) reconcile the competing realities concerning the role of humidity in heat-related health impacts and b) help ensure robust projections of heat-related health risks with climate change. These objectives are critical pathways to identify and communicate effective approaches to cope with present and future heat challenges.DiscussionWe hypothesize six key reasons epidemiological studies have found little impact of humidity on heat-health outcomes: a) At high temperatures, there may be limited influence of humidity on the health conditions that cause most heat-related deaths (i.e., cardiovascular collapse); b) epidemiological data sets have limited spatial extent, a bias toward extratropical (i.e., cooler and less humid), high-income nations, and tend to exist in places where temporal variations in temperature and humidity are positively correlated; c) analyses focus on older, vulnerable populations with sweating, and thus evaporative, impairments that may be further aggravated by dehydration; d) extremely high levels of temperature and humidity (seldom seen in the historical record) are necessary for humidity to substantially impact heat strain of sedentary individuals; e) relationships between temperature and humidity are improperly considered when interpreting epidemiological model results; and f) sub-daily meteorological phenomena, such as rain, occur at high temperatures and humidity, and may bias epidemiological studies based on daily data. Future research must robustly test these hypotheses to advance methods for more accurate incorporation of humidity in estimating heat-related health outcomes under present and projected future climates. https://doi.org/10.1289/EHP11807.

Background Precipitation anomalies are associated with a number of poor health outcomes. One potential consequence of precipitation extremes is human geographic mobility. We evaluated the associations between precipitation anomalies (droughts and heavy rains) and short-term mobility in 23 sub-Saharan African countries by linking satellite data on precipitation to cross-sectional representative surveys. Methods Using data from 23 Demographic and Health Surveys from 2011 to 2017, we estimated the associations between deviations in long-term rainfall trends and short-term mobility among 294,539 women and 136,415 men over 15 years of age. We fit multivariable logistic regression models to assess potential non-linear relationships between rainfall deviations and short-term mobility, adjusting for survey month and socio-demographic covariates, and stratified by participant gender. Furthermore, we assessed whether these associations differed by marital status. Results Rainfall deviations were associated with short-term mobility among women, but not men. The relationship between rainfall deviations and mobility among women was U-shaped, such that women had increased marginal probabilities of mobility in instances of both lower and heavier precipitation. Differences between married and unmarried women were also revealed: among married women, we found positive associations between both rainfall deviation extremes (drought and heavy rains) and mobility; however, among unmarried women, there was only a positive association for heavy rains. Conclusion Precipitation anomalies were associated with short-term mobility among women, which may be in turn associated with poor health outcomes. More research with longitudinal data is needed to elaborate the associations between weather shocks, mobility, and downstream health impacts.

Supplementary Material 1

Supplementary Material 1

Changing environmental conditions constitutes one of the greatest threats to human health by reducing agricultural yields and exacerbating the burden of undernutrition. Mozambique is a region characterized by a high dependence on agricultural productivity and an increasing prevalence of climate shocks in the form of droughts and floods. Low food availability as a result of changing environmental conditions can impair child development and long-term agricultural productivity, thus necessitating e!orts to understand and protect children’s health. Women’s empowerment is strongly associated with children’s nutritional status, such that disparities in maternal autonomy and educational attainment may explain variations in climate-related vulnerabilities in this regional context. The purpose of this research is to determine the extent climate shocks are associated with child undernutrition among di!erent populations in Mozambique by focusing on droughts and floods during the main crop growing season. In addition, this research investigates the potential of women's empowerment for mitigating climate-related vulnerabilities of children. Demographic health data is linked with regional gridded climate data using a stratified regression analysis to provide information on the impact of climate shocks on child undernutrition among livelihood subgroups of croppers and fishers. This cross-sectional study found that exposure to climate shocks during the main rainy season, from November to May, increases the risk of stunting in children under age five and that women’s empowerment may not be a mitigating factor in the protection of children’s health from climate shocks. Identifying population groups most adversely a!ected by climate change will be important for reducing social inequities and achieving the Sustainable Development Goals within Mozambique.

Additional file 7.

Additional file 1. PEP4PA_CONSORT Extension for Cluster Trials 2012 Checklist.

Additional file 4. Unadjusted regression coefficients and 95% confidence intervals (CI) for all outcomes.

Additional file 3. Qualitative tool: interview guide for the population. QualPop.

Additional file 4. Qualitative tool: interview guide for the health service providers. QualHSP.

GPS data processing for all participants in the study

Additional file 5. Marginal estimates for secondary outcomes.

Additional file 6. Sensitivity analyses.

Additional file 2. PEP4PA_TIDieR-Checklist-Word.

Additional file 3. Standardized mean differences.

Additional file 7. Cumulative per person costs for intervention and control conditions.

Additional file 6.

Additional file 1.

Electronic cigarettes (e-cigarettes) are the preferred smoking-cessation aid in the United States; however, there is little evidence regarding long-term effectiveness among those who use them. We used the Population Assessment of Tobacco and Health Study to compare long-term abstinence between matched US smokers who tried to quit with and without use of e-cigarettes as a cessation aid. We identified a nationally representative cohort of 2,535 adult US smokers in 2014-2015 (baseline assessment), who, in 2015-2016 (exposure assessment), reported a past-year attempt to quit and the cessation aids used, and reported smoking status in 2016-2017 (outcome assessment; self-reported ≥12 months continuous abstinence). We used propensity-score methods to match each e-cigarette user with similar nonusers. Among US smokers who used e-cigarettes to help quit, 12.9% (95% confidence interval (CI): 9.1%, 16.7%) successfully attained long-term abstinence. However, there was no difference compared with matched non-e-cigarette users (cigarette abstinence difference: 2%; 95% CI: -3%, 7%). Furthermore, fewer e-cigarette users were abstinent from nicotine products in the long term (nicotine abstinence difference: -4%; 95% CI: -7%, -1%); approximately two-thirds of e-cigarette users who successfully quit smoking continued to use e-cigarettes. These results suggest e-cigarettes may not be an effective cessation aid for adult smokers and, instead, may contribute to continuing nicotine dependence.

Additional file 2. Questionnaire Endline.

Additional file 1.

Additional file 1: Table S1. Oaxaca-Blinder decomposition of differences in daily smoking between high school students and apprentices in the 2008 sample without the variables “parental smoking”: estimates and percentage contributions. Table S2. Oaxaca-Blinder decomposition of differences in daily smoking between high school students and apprentices in 2008 without the variable “money received”: estimates and percentage contributions. Table S3. Oaxaca-Blinder decomposition of differences in daily smoking between high school students and apprentices in the 2008, 2017-A and 2017-B samples. Sensitivity analysis with one model for each independent variable: estimates and percentage contributions.

BackgroundExposure to fine particulate matter (PM2.5) during pregnancy has been shown to be associated with reduced birth weight and racial/ethnic minorities have been found to be more vulnerable. Previous studies have focused on the mean value of birth weight associated with PM2.5, which may mask meaningful differences. We applied a quantile regression approach to investigate the variation by percentile of birth weight and compared non-Hispanic (NH) Black, NH White, and Hispanic mothers.MethodsData for singleton births in California from October 24, 2005 to February 27, 2010 were collected from the birth records accessed from the California Department of Public Health. Air pollution monitoring data collected by the California Air Resources Board and interpolated for each zip code using an inverse-distance weighting approach, and linked to maternal zip code of residence reported on the birth certificate. Multilevel linear regression models were conducted with mother's residential zip code tabulation area as a random effect. Multilevel quantile regression models were used to analyze the association at different percentiles of birth weight (5th, 10th, 25th, 50th, 75th, 90th, 95th), as well as examine the heterogeneity in this association between racial/ethnic groups.ResultsLinear regression revealed that a 10 μg/m3 increase in PM2.5 exposure during pregnancy is associated with a mean birth weight decrease of 7.31 g [95% confidence interval (CI): 8.10, 6.51] and NH Black mothers are the most vulnerable. Results of the quantile regression are not constant across quantiles. For NH Black mothers whose infants had the lowest birthweight of less than 2673 g (5th percentile), a 10 μg/m3 increase in PM2.5 exposure is associated with a decrease of 18.57 g [95% CI: 22.23, 14.91], while it is associated with a decrease of 7.77 g [95% CI: 8.73, 6.79] for NH White mothers and 7.76 [8.52, 7.00] decrease for Hispanic mothers at the same quantile.ConclusionResults of the quantile regression revealed greater disparities, particularly for infants with the lowest birth weight. By identifying vulnerable populations, we can promote and implement policies to confront these health disparities.

Table S1. Number of steps taken per minute during episodes of transfer in public transport trips represented as point locations in the mobility survey (RECORD MultiSensor Study). Table S2. Average number of trips per individual per day according to the main mode in the trip and according to the geographic location of the residence (RECORD MultiSensor Study). (DOCX 17 kb)

Distribution of the “share of total commuting time spent active” among active commuters, N = 537. (DOCX 13 kb)

Sensitivity analysis: association between neighborhood education, distance to work* and the probability of reporting any active commuting (N = 1169). (DOCX 14 kb)

Sensitivity analysis: association between neighborhood education, distance to work* and share of total commuting time spent active among active commuters (N = 537). (DOCX 13 kb)

Additional analysis: association between neighborhood education level and the absolute time of active commuting, N = 537a. (DOCX 12 kb)

Additional file 1. SPIRIT 2013 Checklist: Recommended items to address in a clinical trial protocol and related documents*.

Additional file 1. SPIRIT 2013 Checklist: Recommended items to address in a clinical trial protocol and related documents*.