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The WHO AQGs 2021 incorporates more stringent guidelines for air pollution, which now include both ambient and indoor air quality. We discuss the challenges to meeting the AQGs for indoor air. We suggest a cocktail-like treatment solution that combines efforts from a multidiscipline field of policy, technology, and education., 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 © 2022 Elsevier B.V. All rights reserved.)

Background: Human exposure to multiphase semi-volatile organic compounds (SVOCs) via multiple routes has been associated with health risks. Residential air cleaning interventions remove SVOCs adsorbed on airborne particles, which subsequently affects indoor concentrations of SVOCs in other phases. We aimed to investigate the effect of residential air cleaning interventions on the overall cancer risk associated with multiphase SVOCs., Methods: We simulated concentrations of eight multiphase SVOCs (including seven polycyclic aromatic hydrocarbons [PAHs] and di(2-ethylhexyl) phthalate [DEHP]) using a kinetic partition mass balance model for three exposure scenarios: naturally ventilated residences without intervention (scenario 1), naturally ventilated residences with portable air purifiers (scenario 2), and mechanically ventilated residences with air filtration units (scenario 3). We converted indoor concentrations of the individual PAHs into indoor concentrations of equivalent benzo[a]pyrene (BaP eq ) using the BaP cancer potency equivalent factor for each PAH. We estimated indoor exposure to SVOCs via inhalation, dermal absorption, and ingestion. For each scenario, we calculated the incremental lifetime cancer risk (ILCR) associated with indoor exposure to each SVOC via the three routes and the total ILCR (all three routes combined)., Findings: Mean total ILCRs associated with exposure to BaP eq were 4·42 × 10 -6 (SD 2·84) for scenario 1, 2·36 × 10 -6 (1·53) for scenario 2, and 4·88 × 10 -6 (4·86) for scenario 3. Mean total ILCRs associated with exposure to DEHP were 3·61 × 10 -6 (3·60) for scenario 1, 7·51 × 10 -7 (5·34) for scenario 2, and 1·48 × 10 -5 (2·02) for scenario 3. Ingestion of settled dust was the most important contributor to the total ILCR for both BaP eq and DEHP in all the studied scenarios., Interpretation: The large-scale use of mechanical ventilation systems in urban residences in China needs to be evaluated owing to their potential exacerbation of the cancer risks associated with common indoor SVOCs., Funding: National Key Project of the Ministry of Science and Technology and Natural Science Foundation of China., (Copyright © 2018 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 license. Published by Elsevier Ltd.. All rights reserved.)

Background: The use of ambient air pollution data obtained from central air-monitoring stations as surrogates for participants' exposures to outdoor air pollutants in previous studies may have introduced bias in the estimation of exposure-response associations., Objectives: We investigated and compared the effects of short-term exposure to outdoor particulate matter (PMout) and outdoor-originated equivalent personal PM (PMeq) on lung function in chronic obstructive pulmonary disease (COPD) patients., Methods: A total of 33 doctor-diagnosed stable COPD patients were recruited and repeatedly measured for lung function (totally 170 measurements) in 2013-2014. Daily PMout concentrations were obtained from central-monitoring stations, and daily time-weighted average PMeq concentrations were estimated based on PMout over the study. Associations of PM with lung function were estimated using mixed-effects models., Results: Interquartile range increases in PM2.5out (111.0 μg/m(3), 5-day) and PM10out (112.0 μg/m(3), 3-day) were associated with a 3.3% (95% confidence interval [CI]: -5.8%, -0.8%) reduction and a 2.1% (95%CI: -3.9%, -0.3%) reduction in forced vital capacity (FVC), respectively. Similar results were found for forced expiratory volume in 1s (FEV1). An interquartile range increase in PM2.5eq (45.3 μg/m(3), 3-day), but not PM10eq, was still associated with a 1.7% (95%CI: -3.3%, -0.1%) reduction in FVC., Conclusions: Our study may provide a novel approach to assess the association of ambient PM with health observations with improved accuracy., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Exposure to airborne semivolatile organic compounds (SVOCs) in indoor and outdoor environments of humans may lead to adverse health risks. Thus, we established a model to evaluate exposure to airborne SVOCs. In this model, SVOCs phase-specific concentrations were estimated by a kinetic partition model accounting for particle dynamics. The exposure pathways to airborne SVOCs included inhalation exposure to gas- and particle-phases, dermal exposure by direct gas-to-skin pathway and dermal exposure by direct particle deposition. Exposures of defined "reference people" to two typical classifications of SVOCs, one generated from both indoor and outdoor sources, represented by polycyclic aromatic hydrocarbons (PAHs), and the other generated mainly from only indoor sources, represented by di 2-ethylhexyl phthalate (DEHP), were analyzed as an example application of the model. For PAHs with higher volatility, inhalation exposure to gas-phase, ranging from 6.03 to 16.4 ng/kg/d, accounted for the most of the exposure to the airborne phases. For PAHs with lower volatility, inhalation exposure to particle-phase, ranging from 1.48 to 1.53 ng/kg/d, was the most important exposure pathway. As for DEHP, dermal exposure via direct gas-to-skin pathway was 460 ng/kg/d, which was the most striking exposure pathway when the barrier effect of clothing was neglected.

Wearable ionization air cleaners are compact in size and marketed for personal respiratory protection by removing air pollutants from users' breathing zone. In this study, ozone emission and particle removal rates of four wearable ionization air cleaners (namely, AC1 through AC4) were evaluated inside a 0.46 m3stainless steel chamber. Continuous measurements were conducted for ozone concentration, PM2.5concentration, and particle size distribution in the size range of 18.1–289 nm. Two of the four wearable air cleaners (i.e., AC1 and AC2) had detectable ozone emissions. The 10-h average ozone emission rates were quite different (i.e., 0.67 mg·h−1for AC1 and 3.40 × 10−2mg·h−1for AC2); however, the ozone emissions were negligible for AC3 and AC4. The number removal rates for particles within the measured size range were highly variable (i.e., 2.20 h−1, 0.52 h−1, 8.10 h−1, and 27.9 h−1for AC1 through AC4, respectively). The corresponding mass removal rates of PM2.5were 1.85 h−1, 0.48 h−1,1.52 h−1, and 5.37 h−1, respectively. Regulatory guidelines are needed to assure these devices can effectively remove particles without ozone emissions to protect public health. Copyright © 2016 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

Air change rate is a very important parameter for indoor air quality estimation as it influences the exchange of air pollutants between indoor and outdoor environments. Consequently, determining air change rate distribution is indispensable for assessment of a population's exposure to air pollutants. In this study, the annual and seasonal average infiltration rates (air change rate for window close conditions) of 180 representative residences were simulated using the multi-zone network airflow model (CONTAM) to understand the residential infiltration rate distributions in Beijing. The representative residences were selected by probability sampling based on building characteristics, including building type, floor area, number of rooms, construction year, number of floors, and building orientation. The results show that the annual average infiltration rates in Beijing range from 0.02 to 0.82 h −1 with a median value of 0.16 h −1 . The empirical distributions of the annual and seasonal average residential infiltration rates in Beijing were provided. The annual average infiltration rates were also found to well fit a two-parameter lognormal distribution, the median and standard deviation of which is −1.79 and 0.62. Infiltration rates of 34 residences in Beijing were measured via the CO 2 decay method, and the measured infiltration rates of residences matched the simulated distribution well. The differences between the simulated and measured infiltration rates are discussed. [ABSTRACT FROM AUTHOR]

Household air pollution prevails in rural residences across China, yet a comprehensive nationwide comprehending of pollution levels and the attributable disease burdens remains lacking. This study conducted a systematic review focusing on elucidating the indoor concentrations of prevalent household air pollutants—specifically, PM2.5, PAHs, CO, SO 2 , and formaldehyde—in rural Chinese households. Subsequently, the premature deaths and economic losses attributable to household air pollution among the rural population of China were quantified through dose-response relationships and the value of statistical life. The findings reveal that rural indoor air pollution levels frequently exceed China's national standards, exhibiting notable spatial disparities. The estimated annual premature mortality attributable to household air pollution in rural China amounts to 966 thousand (95% CI: 714–1226) deaths between 2000 and 2022, representing approximately 22.2% (95% CI: 16.4%−28.1%) of total mortality among rural Chinese residents. Furthermore, the economic toll associated with these premature deaths is estimated at 486 billion CNY (95% CI: 358–616) per annum, constituting 0.92% (95% CI: 0.68%−1.16%) of China's GDP. The findings quantitatively demonstrate the substantial disease burden attributable to household air pollution in rural China, which highlights the pressing imperative for targeted, region-specific interventions to ameliorate this pressing public health concern. [Display omitted] • Indoor air pollution level in rural China was analyzed via a literature review. • Exposure to the pollutant exhibits heterogeneity across different spatial region. • Concerned air pollution attributes to 966 thousand premature deaths annually. • PM2.5 and CVD are key pollutant and disease contributing to health effects. • Targeted regional policies are needed to control rural household air pollution. [ABSTRACT FROM AUTHOR]