Yihui Yin

Background High-level exposure to indoor air pollutants (IAPs), including volatile organic compounds (VOCs), has substantially contributed to the burden of disease in China over the past two decades. However, the contributions of different indoor VOC sources to the associated health burden remain poorly understood. Objective This study aimed to estimate source-specific residential VOC concentrations and the associated burden of disease to identify and rank the major sources of indoor VOCs in China. Methods Indoor concentrations of 39 VOCs were repeatedly measured across seasons from 2016 to 2017 in 249 residences from nine Chinese cities. We developed a novel integrated approach that combined positive matrix factorization (PMF) for source apportionment of indoor VOCs with the proportional population attributable fraction (PAF) method to quantify source-specific health burden. Results In 2017, the disability-adjusted life years (DALYs) attributable to residential VOCs across nine Chinese provinces reached 134.2 (95% UI: 65.7–225.0) per 100,000, resulting in financial costs of 28.1 (13.8–47.1) billion CNY. The PMF analysis identified six indoor sources and three outdoor sources contributing to indoor VOC concentrations. The three leading sources, which were interpreted as engineered wood products and furniture, outdoor vehicle exhaust, and cooking and indoor combustion, accounted for 42.7%, 25.9%, and 11.0% of the VOC-attributable DALYs, respectively. Significance This study prioritized controlling engineered wood products and furniture to mitigate indoor VOC health burdens in China, and proposed a generalizable health-based approach to rank sources of other IAPs. Impact This is the first study to rank the sources of indoor residential VOCs based on attributable health burden. The findings provide quantitative evidence to prioritize control strategies targeting the dominant residential VOC sources in China, such as engineered wood products and furniture. The proposed approach can be extended to other IAPs and may support future cost-benefit analyses of source-specific intervention strategies.

High-level exposure to indoor air pollutants (IAPs), including volatile organic compounds (VOCs), has substantially contributed to the burden of disease in China over the past two decades. However, the source contributions to the indoor VOC-related health burden remain unknown. This study utilized a novel approach based on positive matrix factorization (PMF) of indoor multipollutant data to estimate the source-specific residential VOC concentrations and associated burden of disease. Indoor concentrations of 39 VOCs were collected repeatedly in different seasons from 2016 to 2017 in 249 residences across nine cities in China. In 2017, the disability-adjusted life years (DALYs) attributable to residential VOC exposure across nine provinces in China reached 134.2 (95% UI: 65.7 – 225.0) per 100,000, resulting in financial costs of 28.1 (13.8 – 47.1) billion CNY. Contributions to indoor VOC concentrations from six indoor sources and three outdoor sources were derived by PMF. The top three sources, i.e., wood building materials and furniture, outdoor vehicle exhaust, and cooking and indoor combustion, accounted for 42.7%, 25.9%, and 11.0% of the VOC-attributable DALYs, which suggests prioritizing controlling these sources in China. This approach can be extended to other IAPs and provide fundamental data for future cost-benefit analysis of source control interventions. TOC Art: Synopsis: This novel method leverages multi-seasonal and multi-room residential VOC measurements to identify emission sources, quantify source-specific exposure concentrations, and estimate source-specific health burden, thus prioritizing the sources needing control.

The aircraft cabin provides a unique indoor environment compared to other building environments. Tetrachloroethylene (PCE) is widely found in cabins and has clear adverse health impacts. This study investigated the PCE pollution characteristics in 56 aircraft cabins using on-flight Tenax-TA tube sampling and GC-MS analysis. PCE was detected at a high rate of 79% in sampled flights, indicating widespread contamination within the cabins. The mean concentration of PCE was 10.12 μg/m³, exceeding the 2.06 μg/m³ observed in residences in a previous study. The positive matrix factorization (PMF) model was used to identify potential sources of PCE in cabins. Six categories of sources were determined, including in-cabin cleaning products, aircraft cleaning/maintenance, cabin interior material, aircraft and vehicle exhaust, non-fuel oil and ozone-associated chemical reactions. The biggest PCE source in cabins was attributed to in-cabin cleaning products (45.30%), followed by cabin interior materials (24.90%), and aircraft cleaning/maintenance (19.82%). The findings of this study are beneficial to improving aircraft cabin air quality, reducing harmful pollutant exposure for cabin crew and passengers.

Over the past few years, surface ozone (O₃) pollution has dominated China’s air pollution as particulate matter has decreased. In Beijing, the annual average concentrations of ground-level O₃ from 2015 to 2020 regularly increased from 57.32 to 62.72 μg/m³, showing a change of almost 9.4%, with a 1.6% per year increase. The meteorological factors are the primary influencer of elevated O₃ levels; however, their importance and heterogeneity of variables remain rarely understood. In this study, we used 13 meteorological factors and 6 air quality (AQ) parameters to estimate their influencing score using the random forest (RF) algorithm to explain and predict ambient O₃. Among the meteorological variables and overall, both land surface temperature and temperature at 2 m from the surface emerged as the most influential factors, while NO₂ stood out as the highest influencing factor from the AQ parameters. Indeed, it is crucial and imperative to reduce the temperature caused by climate change in order to effectively control ambient O₃ levels in Beijing. Overall, meteorological factors alone exhibited a higher coefficient of determination (R²) value of 0.80, compared with AQ variables of 0.58, for the post-lockdown period. In addition, we calculated the number of days O₃ concentration levels exceeded the WHO standard and newly proposed peak-season maximum daily 8-h average (MDA8) O₃ guideline for Beijing. The exceedance number of days from the WHO standard of MDA8 ambient O₃ was observed to be the highest in June, and each studied year crossed peak season guidelines by almost 2 times margin. This study demonstrates the contributions of meteorological variables and AQ parameters in surging ambient O₃ and highlights the importance of future research toward devising an optimum strategy to combat growing O₃ pollution in urban areas. Graphical Abstract

Ozone and byproducts of ozone-initiated reactions are among the primary pollutants in aircraft cabins. However, investigations of the spatial distribution and reaction mechanisms of these pollutants are insufficient. This study established a computational fluid dynamics-based model to evaluate ozone and byproduct distribution, considering ozone reactions in air, adsorption onto surfaces, and byproduct desorption from surfaces. The model was implemented in an authentic single-aisle aircraft cabin and validated by measurements recorded during the aircraft cruise phase. Ozone concentrations in the supply air-dominated area were approximately 50% higher than that in the passenger breathing zone, suggesting that human surfaces represent a significant ozone sink. The deposition velocity onto human bodies was 21.83 m/h, surpassing 3.97 m/h on other cabin interior surface areas. Our model provides a mechanistic tool to analyze ozone and byproduct concentration distributions, which would be useful for assessing passenger health risks and for developing strategies for healthier aircraft cabin environments.