The burden of disease attributable to indoor air pollutants in China from 2000 to 2017.

BACKGROUND: High-level exposure to indoor air pollutants (IAPs) and their corresponding adverse health effects have become a public concern in China in the past 10 years. However, neither national nor provincial level burden of disease attributable to multiple IAPs has been reported for China. This is the first study to estimate and rank the annual burden of disease and the financial costs attributable to targeted residential IAPs at the national and provincial level in China from 2000 to 2017. METHODS: We first did a systematic review and meta-analysis of 117 articles from 37 231 articles identified in major databases, and obtained exposure-response relationships for the candidate IAPs. The exposure levels to these IAPs were then collected by another systematic review of 1864 articles selected from 52 351 articles. After the systematic review, ten IAPs with significant and robust exposure-response relationships and sufficient exposure data were finally targeted: PM2·5, nitrogen dioxide, sulphur dioxide, ozone, carbon monoxide, radon, formaldehyde, benzene, toluene, and p-dichlorobenzene. The annual exposure levels in residences were then evaluated in all 31 provinces in mainland China continuously from 2000 to 2017, using the spatiotemporal Gaussian process regression model to analyse indoor originating IAPs, and the infiltration factor method to analyse outdoor originating IAPs. The disability-adjusted life-years (DALYs) attributable to the targeted IAPs were estimated at both national and provincial levels in China, using the population attributable fraction method. Financial costs were estimated by an adapted human capital approach. FINDINGS: From 2000 to 2017, annual DALYs attributable to the ten IAPs in mainland China decreased from 4620 (95% CI 4070-5040) to 3700 (3210-4090) per 100 000. Nevertheless, in 2017, IAPs still ranked third among all risk factors, and their DALYs and financial costs accounted for 14·1% (95% CI 12·3-15·6) of total DALYs and 3·45% (3·01-3·82) of the gross domestic product. Specifically, the rank of ten targeted IAPs in order of their contribution to DALYs in 2017 was PM2·5, carbon monoxide, radon, benzene, nitrogen dioxide, ozone, sulphur dioxide, formaldehyde, toluene, and p-dichlorobenzene. The DALYs attributable to IAPs were 9·50% higher than those attributable to outdoor air pollution in 2017. For the leading IAP, PM2·5, the DALYs attributable to indoor origins are 18·3% higher than those of outdoor origins. INTERPRETATION: DALYs attributed to IAPs in China have decreased by 20·0% over the past two decades. Even so, they are still much higher than those in the USA and European countries. This study can provide a basis for determining which IAPs to target in various indoor air quality standards and for estimating the health and economic benefits of various indoor air quality control approaches, which will help to reduce the adverse health effects of IAPs in China. FUNDING: The National Key Research and Development Program of China and the National Natural Science Foundation of China.

Indoor exposure levels and risk assessment of volatile organic compounds in residences, schools, and offices in China from 2000 to 2021: A systematic review.

The last two decades have witnessed rapid urbanization and economic growth accompanied by severe indoor air pollution of volatile organic compounds (VOCs) in China. However, indoor VOC pollution across China has not been well characterized and documented. This study is a systematic review of field measurements of eight target VOCs (benzene, toluene, xylenes, acetaldehyde, p-dichlorobenzene, butadiene, trichloroethylene, and tetrachloroethylene) in residences, offices, and schools in China from 2000 to 2021. The results show that indoor pollution of benzene, toluene, and xylenes has been more serious in China than in other countries. Spatiotemporal distribution shows lower indoor VOC levels in east and south-east regions and a declining trend from 2000 to 2021. Moving into a dwelling more than 1 year after decoration and improving ventilation could significantly reduce exposure to indoor VOCs. Reducing benzene exposure is urgently needed because it is associated with greater health risks (4.5 × 10-4 for lifetime cancer risk and 8.3 for hazard quotient) than any other VOCs. The present study enriches the database of indoor VOC levels and provides scientific evidence for improving national indoor air quality standards as well as estimating the attributable disease burden caused by VOCs in China.

Indoor exposure to phthalates and its burden of disease in China.

China's profoundly rapid modernization in the past two decades has resulted in dramatic changes in indoor environmental exposures. Among these changes, exposure to phthalates has attracted increasing attention. We aimed to characterize indoor phthalate exposure and to estimate the disease burden attributable to indoor phthalate pollution from 2000 to 2017 in China. We integrated the national exposure level of indoor phthalates from literature through systematic review and Monte Carlo simulation. Dose-response relationships between phthalate exposure and health outcomes were obtained by systematic review and meta-analysis. Based on existing models for assessing probabilities of causation and a comprehensive review of available data, we calculated the disability-adjusted life years (DALYs) among the general Chinese population resulting from exposure to indoor phthalate pollution. We found that DnBP, DiBP, and DEHP were the most abundant phthalates in indoor environments of residences, offices, and schools with medians of national dust phase concentration from 74.5 µg/g to 96.3 µg/g, 39.6 µg/g to 162.5 µg/g, 634.2 µg/g to 1,394.7 µg/g, respectively. The national equivalent exposure for children to phthalates in settled dust was higher than that of adults except for DiBP and DnOP. Dose-response relationships associated with DEP, DiBP, DnBP, BBzP, and DEHP exposures were established. Between 2000 and 2017, indoor phthalate exposure in China has led to 3.32 million DALYs per year, accounting for 0.90% of total DALYs across China. The annual DALY associated with indoor phthalate pollution in China was over 2000 people per million, which is about 2~3 times of the DALY loss due to secondhand smoke (SHS) in six European countries or the sum of the DALY loss caused by indoor radon and formaldehyde in American homes. Our study indicates a considerable socioeconomic impact of indoor phthalate exposure for a modernizing human society. This suggest the need for relevant national standard and actions to reduce indoor phthalate exposure.

Indoor polybrominated diphenyl ethers in urban China: An exposure and risk assessment based on settled dust from selected urban regions.

In this study, measurements of seven typical polybrominated diphenyl ethers (PBDEs) in indoor settled dust were summarized in selected urban regions of China. BDE-209 was the most dominant congener in settled dust (1.4-101 µg/g), with a mean contribution of 95%. Indoor exposures to PBDEs were estimated via inhalation, dust ingestion, and dermal absorption. The average daily intake of ΣPBDE was 4.9 to 19.1 ng/day/kg for all the population groups, with >80% of the total exposures from dust ingestion. Exposures in commuting environments (contributing 60%-80% of the total exposures) were higher than those in other microenvironments. The means of hazard indexes ranged from 1.66 × 10-3 to 5.26 × 10-3, which were mainly as a result of exposure to BDE-209, BDE-47, and BDE-99. The average lifetime cancer risks were from 0.03 × 10-9 to 2.37 × 10-9, which indicated the acceptable health risks resulting from indoor PBDE exposure for the Chinese population. The present study could provide valuable information that could be helpful for decision-makers, analysts and researchers to develop, implement and evaluate the effectiveness of interventions for the reduction of exposures to semi-volatile organic compounds (SVOCs) for large population groups in China.

Exposure to commonly-used phthalates and the associated health risks in indoor environment of urban China.

Rapid urbanization and modernization have increased exposures to phthalates from synthetic materials used indoors in China. However, exposure to phthalates from indoor environment and the associated health risks to the urban population have not been adequately characterized and documented. In this study, we summarized the recent measurements of five commonly-used phthalates in indoor environment in urban China and documented their distributions. Based on the activity patterns and exposure factors of Chinese population, Monte-Carlo simulation was used to derive their exposures. On average, the daily intake of all the targeted phthalates was 3.6 µg/kg/day for adults; and for children it ranged from 4.4 µg/kg/day to 8.1 µg/kg/day. For children, the total risk from exposures inside residences and offices was 32%-90% and 4%-19%, respectively. From commuting environments and other indoor environments, it was 5%-31%, and 3%-26%, respectively. For adults, the total risk from residences and offices was 26%-78% and 9%-35%. Additionally, from commuting environments and other indoor environments, it was 8%-35% and 5%-11%, respectively. The non-carcinogenic risk assessment was based on a cumulative Tolerable Daily Intake (TDIcum), with means ranging from 0.18 to 0.41, which was mainly as a result of exposure to DiBP and DnBP. The means for lifetime cancer risk resulting from DEHP exposure ranged from 0.4 × 10-6 to 2.0 × 10-6 for urban population groups. For 80% of working adults and 40%-75%% of children, their cancer risks exceeded the EPA's benchmark (1.0 × 10-6). The present study could provide important information for decision makers to reduce indoor phthalate exposures as well as the associated health risks for larger population groups in Chinese cities.

Risk assessment of inhalation exposure to VOCs in dwellings in Chongqing, China.

This paper investigated the concentrations of eight types of indoor VOCs - benzene, toluene, xylenes, butyl acetate, styrene, isopropylbenzene, undecane and formaldehyde. The tests were carried out in 50 dwellings in the main urban areas of Chongqing, China. According to the detected concentration, toluene was the most predominant among all the targeted compounds. Benzene and formaldehyde concentrations were lower than the reference levels regulated by the Chinese National Standard (GB/T 50325). Based on the activity patterns and exposure factors of adults in urban Chongqing, we used concentration data to estimate adults' inhalation exposures as well as health risks using Monte-Carlo simulations. The results indicated that the exposure doses of benzene and formaldehyde exceeded the benchmark. The highest hazard quotient (HQ) values were found in the case of formaldehyde (median = 0.293 for females and 0.292 for males) and the hazard index (HI) values were 0.326 and 0.325 for females and males, respectively. The highest lifetime cancer risk (LCR) values were found in formaldehyde (median = 7.16 × 10-5 for females; 6.56 × 10-5 for males). Formaldehyde was found to be the most important pollutant with relatively high toxic and carcinogenic risk levels, based on the exposure and health assessment. This was followed by benzene, toluene, xylenes and butyl acetate. This study can help us better understand the concentration levels of VOC contaminants in residential buildings, and help select appropriate decoration materials for buildings.