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Background There is some evidence that dampness, mould and cockroaches can increase the risk of respiratory infections in children but few studies exist from China on this topic. Aim To study associations between domestic early life exposure to biological indoor factors (dampness, mould, cats, dogs, rats, cockroaches), cleaning habits and common cold among pre-school children across China. Methods Children aged 3–6 years (n = 39,782) were recruited from randomly selected day care centres in seven cities in China. Data on common cold and prenatal and postnatal exposure to dampness, mould, windowpane condensation in wintertime (WPC), cats, dogs, cockroaches and rats were assessed by a parentally administered questionnaire. Data on annual ambient temperature and PM 10 was assessed on city level. Associations between high frequency (> 5 colds per year) and long duration (≥ 2 weeks) of common colds in the past year and exposure were calculated by multilevel logistic regression. Results A total of 9.2% had a high frequency and 11.9% had long duration of common cold. Exposure to mould (OR = 1.38, 95% CI 1.24–1.53) and WPC (OR 1.23, 95%CI 1.13–1.33) at birth was associated with frequent common cold. Exposure to dogs at birth was associated with long duration of common cold. (OR = 1.22, 95% CI 1.06–1.41). Exposure to mould (OR = 1.36, 95% CI 1.22–1.54), WPC (OR = 1.27, 95%CI 1.17–1.39) and water leakage (OR 1.34, 95% CI 1.20–1.49) in the current home was associated with frequent common cold. Presence of cockroaches were positively (OR = 1.12, 95% CI 1.02–1.24) and presence of rats (OR = 0.86, 95% CI 0.77–0.96) negatively associated with high frequency of common cold. Daily cleaning was negatively associated with frequent common cold (OR = 0.89, 95% CI 0.81–0.97). Similar associations for mould, WPC, cockroaches and rats were found for long duration. Ambient PM 10 (OR = 1.21, 95% CI 1.21–1.35 per 10 μg/m 3 ) and temperature (OR = 1.13, 95% CI 1.06–1.35 °C) on city level were associated with high frequency of common cold. Associations between cat keeping and high frequency of common cold were found only in southern China. Associations with cockroaches were stronger in northern China. Associations with dampness and mould were the same in the north and south. Conclusions Indoor mould, water damage, windowpane condensation, cockroaches and keeping cats or dogs as pets can be risk factors for common cold while daily cleaning can be protective factor. PM 10 and a warmer climate zone can be other risk factors for common cold. [ABSTRACT FROM AUTHOR]

Background: Increasing prevalence of childhood allergic rhinitis(AR) needs a deeper understanding on the potential adverse effects of early life exposure to air pollution., Objectives: The main aim was to evaluate the effects of maternal exposure to PM 2.5 and chemical constituents during pregnancy on preschool children's AR, and further to explore the modification effects of regions and exclusive breastfeeding., Methods: A multi-center population-based study was performed in 6 cities from 3 regions of China in 2011-2012. Maternal exposure to ambient PM 2.5 and main chemical constituents(BC, OM, SO 4 2- , NO 3 - , NH 4 + ) during pregnancy was assessed and a longitudinal prospective analysis was applied on preschool children's AR. The modification effects of regions and exclusive breastfeeding were investigated., Results: A total of 8.8% and 9.8% of children reported doctor-diagnosed allergic rhinitis(DDAR) and current hay fever, respectively, and 48.6% had less than 6 months of exclusive breastfeeding. The means of PM 2.5 during pregnancy were 52.7 μg/m 3 , 70.3 μg/m 3 and 76.4 μg/m 3 in the east, north and central south of China, respectively. Multilevel log-binomial model regression showed that each interquartile range(IQR) increase of PM 2.5 during pregnancy was associated with an average increase in prevalence ratio (PR) of DDAR by 1.43(95% confidence interval(CI): 1.11, 1.84) and current hay fever by 1.79(95% CI: 1.26, 2.55), respectively. Among chemical constituents, black carbon (BC) had the strongest associations. Across 3 regions, the eastern cities had the highest associations, followed by those in the central south and the north. For those equal to or longer than 6 months of exclusive breastfeeding, the associations were significantly reduced., Conclusions: Children in east of China had the highest risks of developing AR per unit increase of maternal exposure to PM 2.5 during pregnancy, especially BC constituent. Remarkable decline was found in association with an increase in breastfeeding for ≥6 months, in particular in east of China., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Given a large fraction of people's exposure to urban PM 2.5 occur indoors, reducing indoor PM 2.5 levels may offer a more feasible and immediate way to save substantial lives and economic losses attributable to PM 2.5 exposure. We aimed to estimate the premature mortality and economic loss reductions associated with achieving the newly established Chinese indoor air guideline and a few hypothetical indoor PM 2.5 guideline values. We used outdoor PM 2.5 concentrations from 1497 monitoring sites in 339 Chinese cities in 2015, coupled with a steady-state mass balance model, to estimate indoor concentrations of outdoor-infiltrated PM 2.5 . Using province-specific time-activity patterns for urban residents, we estimated outdoor and indoor exposures to PM 2.5 of outdoor origin. We then proceeded to use localized census-based concentration-response models and the value of statistical life estimates to calculate premature deaths and economic losses attributable to PM 2.5 exposure across urban China. Finally, we estimated potentially avoidable mortality and corresponding economic losses by meeting the current 24-hour based guideline and various hypothetical indoor limits for PM 2.5 . In 2015 in urban areas of mainland China, the city-specific annual mean outdoor and indoor PM 2.5 concentrations ranged 9-108 μg/m 3 and 5-56 μg/m 3 , respectively. Indoor exposures contributed 62%-91% daily and 68%-83% annually to the total time-weighted exposures. The potential reductions in total deaths and economic losses for the scenario in which daily indoor concentrations met the current guideline of 75 μg/m 3 , 37.5 μg/m 3 , and 25 μg/m 3 were 16.9 (95% CI: 0.7-62.1) thousand, 87.7 (95% CI: 9.7-197.7) thousand, and 165.5 (95% CI: 30.8-304.0) thousand, respectively. The corresponding reductions in economic losses were 5.7 (95% CI: 0.2-34.8) billion, 29.4 (95% CI: 2.4-109.6) billion, and 55.2 (95% CI: 7.7-168.0) billion US Dollars, respectively. Deaths and economic losses would be reduced exponentially within the range of 0-75 μg/m 3 for hypothetical indoor PM 2.5 limits. The findings demonstrate the effectiveness of reducing indoor concentrations of outdoor-originated PM 2.5 in saving substantial lives and economic losses in China. The analysis provides quantitative evidence to support the implementation of an indoor air quality guideline or standard for PM 2.5 ., (Copyright © 2020 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

The long-term effects of ambient PM 2.5 and chemical constituents on childhood pneumonia were still unknown. A cross-sectional study was conducted in 30,315 children in the China Children, Homes, Health (CCHH) project, involving 205 preschools in six cities in China, to investigate the long-term effects of PM 2.5 constituents on lifetime-ever diagnosed pneumonia. Information on the lifetime-ever pneumonia and demographics were collected by validated questionnaires. The lifetime annual average ambient PM 2.5 , ozone and five main PM 2.5 constituents, including SO 4 2- , NO 3 - , NH 4 + , organic matter (OM) and black carbon (BC), were estimated according to preschool addresses by a combination of satellite remote sensing, chemical transport modeling and ground-based monitors. The prevalence of lifetime-ever diagnosed pneumonia was 34.5% across six cities and differed significantly among cities (p = 0.004). The two-level logistic regression models showed that the adjusted odds ratio for PM 2.5 (per 10 µg/m 3 ) and its constituents (per 1 µg/m 3 )-SO 4 2- , NO 3 - , NH 4 + , and OM were 1.12 (95% CI:1.07-1.18), 1.02 (1.00-1.04), 1.06 (1.04-1.09), 1.05 (1.03-1.07) and 1.09 (1.06-1.12), respectively. Children in urban area, aged < 5 years and breastfeeding time < 6 months enhanced the risks of pneumonia. Our study provided robust results that long-term levels of ambient PM 2.5 and its constituents increased the risk of childhood pneumonia, especially NH 4 + , NO 3 - and OM., (Copyright © 2020 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

We studied indoor sources of indoor particulate matter (PM), outdoor air pollution and antibiotic use in relation to asthma, rhinitis and eczema among pre-school children and investigated synergistic effects between PM and antibiotics use. Children (3-6y) from randomly selected day care centres in seven cities across China were included (n = 39,782). Data on ambient temperature and air pollution were collected from local monitoring stations. Data on indoor PM sources (ETS, burning of incense or mosquito coils and biomass for cooking), antibiotics use and health (doctor diagnosed asthma and rhinitis, lifetime eczema, current wheeze and current rhinitis) were assessed by a parental questionnaire. Associations were calculated by multilevel logistic regression. Asthma diagnosis was associated with outdoor temperature, NO 2 and burning mosquito coils. Rhinitis diagnosis was associated with NO 2 , ETS, gas cooking and burning biomass for cooking. Lifetime eczema was associated with temperature, PM 10, NO 2 , ETS, biomass cooking and burning mosquito coils. Burning incense was associated with current wheeze and current rhinitis. Children using antibiotics had more asthma, wheeze, rhinitis, and eczema. Excluding children with respiratory infections did not change associations with antibiotics use. Antibiotics use enhanced the effects of ETS and PM 10 (a synergistic effect). In conclusion, a warmer climate, outdoor NO 2 and PM 10, ETS, gas cooking and burning biomass, incense and mosquito coils can increase the risk of asthma, wheeze, rhinitis and eczema among pre-school children in China. Antibiotics use is a risk factor for childhood asthma, wheeze, rhinitis and eczema and ETS and outdoor PM 10 can enhance the effect., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)