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Background Studies have reported that exposure to air pollution during pregnancy was associated with preterm birth (PTB). However, it remains unknown whether this association differs between local residents and migrants. Objective This study aimed to differentiate the associations between maternal air pollution exposure and PTB between local residents and migrants. Methods We established a retrospective birth cohort in seven Chinese cities in Pearl River Delta (PRD) region during 2015–2017. The mothers were included in the cohort at their first time of hospital visit for pregnancy, and the endpoint events were identified using the birth registry. The air pollution exposure was estimated based on the daily air pollution concentrations in the nearby air monitoring stations during different pregnancy periods. Cox proportional hazards models were utilized to estimate the associations between each air pollutant and PTB for different pregnancy periods. Results Our cohort included a total of 628,439 mother-and-live-birth pairs. Among them, 308,201 women were local residents, and 320,238 were migrants. We observed stronger effects of air pollutants among the migrants than the local residents. For the exposure during the entire pregnancy, the hazard ratio (HR) among the migrants and local residents were 1.56 (95% CI: 1.50, 1.63) and 0.98 (95% CI: 0.93, 1.02) for each 10 μg/m3 increase in PM2.5, 1.32 (95% CI: 1.27, 1.39) and 1.18 (95% CI: 1.12, 1.23) for each 10 ppb increase in O3, and 1.48 (95% CI: 1.40, 1.57) and 0.99 (95% CI: 0.93, 1.05) for each 10 μg/m3 increase in SO2, respectively. Similarly higher effects were observed among the migrants for the exposures in different trimesters of pregnancy. However, the effects of NO2 were comparable between the two groups. Conclusion Our study suggests that maternal PM2.5, O3 and SO2 exposures might be important risk factors of preterm birth, particularly among the migrants. More specific protective and education measures should be considered for the migrant pregnant women.

The World Health Organization sets up the Ambient Air Quality Guidelines mainly based on short-term and long-term health effects of air pollution. Previous studies, however, have generally revealed a non-threshold concentration-response relationship between air pollution and health, making it difficult to determine a concentration, below which no obvious health effects can be observed. Here we proposed a novel approach based on the concept of “number needed to treat”, specifically, we calculated the reduction in air pollution concentrations needed to avoid one death corresponding to different hypothetical concentration standards; the one with the smallest value would be the most practical concentration standard. As an example, we applied this approach to the daily standard of ambient PM2.5 (particulate matter with aerodynamic diameter ≤2.5 μm) in four Chinese cities. The calculation was based on the association between daily mortality and ambient PM2.5, which was examined by a generalized additive model with adjustment of important covariates. Significant associations were observed between PM2.5 and mortality. Our analyses suggested that it is appropriate to have 50 μg/m3 as the daily standard of ambient PM2.5 for the study area, compared to the current standard of which were directly adopted from the national standard of 75 μg/m3. This novel approach should be considered when planning and/or revising the ambient air quality guidelines/standards.

Background: Previous studies have reported that maternal exposure to particles with aerodynamic diameter

Background Fine particulate matter (Particulate matter with diameter ≤ 2.5 μm) is associated with multiple health outcomes, with varying effects across seasons and locations. It remains largely unknown that which components of PM2.5 are most harmful to human health. Methods We systematically searched all the relevent studies published before August 1, 2018, on the associations of fine particulate matter constituents with mortality and morbidity, using Web of Science, MEDLINE, PubMed and EMBASE. Studies were included if they explored the associations between short term or long term exposure of fine particulate matter constituents and natural, cardiovascular or respiratory health endpoints. The criteria for the risk of bias was adapted from OHAT and New Castle Ottawa. We applied a random-effects model to derive the risk estimates for each constituent. We performed main analyses restricted to studies which adjusted the PM2.5 mass in their models. Results Significant associations were observed between several PM2.5 constituents and different health endpoints. Among them, black carbon and organic carbon were most robustly and consistently associated with all natural, cardiovascular mortality and morbidity. Other potential toxic constituents including nitrate, sulfate, Zinc, silicon, iron, nickel, vanadium, and potassium were associated with adverse cardiovascular health, while nitrate, sulfate and vanadium were relevant for adverse respiratory health outcomes. Conclusions Our analysis suggests that black carbon and organic carbon are important detrimental components of PM2.5, while other constituents are probably hazardous to human health. However, more studies are needed to further confirm our results.

Background Ambient air pollutant directly contacts with the eyes, however, the effect of ambient fine particulate matter (PM2.5) and ozone (O3) on vision impairment, such as presbyopia, has been kept largely unknown. Methods We surveyed a total of 36,620 participants aged 50 years and above in six low- and middle-income countries. Ambient annual concentrations of PM2.5 and O3 for the residential community were estimated using satellite data and chemical transport model. A mixed effects model was utilized to assess the effects of ambient PM2.5 and O3 on presbyopia, as well as their combined effects. Results A total of 13,841 presbyopia cases were identified among the participants with a prevalence rate of 41.17%. For both PM2.5 and O3, we found a J-shaped exposure-response relationship with the threshold being identified at 15 μg/m3 for PM2.5 and 55 μg/m3 for O3. The odds ratio (OR) of presbyopia was 1.15 (95% CI: 1.09, 1.21) for each 10 μg/m3 increase in PM2.5 above 15 μg/m3 and 1.37 (95% CI: 1.23, 1.54) for O3 above 55 μg/m3 after adjusting for various potential confounding factors. There appeared to be a synergistic interaction between ambient PM2.5 and O3 on presbyopia in the additive model, the combined effect was significantly larger than the sum of their individual effects, with a synergistic index of 2.39. Conclusion This study supports that exposures to ambient PM2.5 and O3 might be important risk factors of presbyopia among old adults, and simultaneously exposure to high level of the two pollutants could intensify their individual effects.

The linkage between ambient air pollution exposure and occurrence of diabetes mellitus is not well defined. This study examined the association between exposure to fine particles (PM2.5) and the prevalence of diabetes among Chinese elderly people. We surveyed 11,504 adults aged ≥50 years in China, estimated the annual concentrations of ambient PM2.5 using a satellite-based model of aerosol optical depth information. We employed a generalized mixed effects model to examine the association between PM2.5 and the prevalence of diabetes and explored potential effect modifiers. We estimated diabetes burden attributable to ambient PM2.5 if the observed association is indeed causal. The diabetes prevalence among the participants was 6.5% (n = 745). Our analysis found a statistically significant association between PM2.5 and diabetes. The adjusted odds ratio was 1.27 (95% confidence interval (CI), 1.12, 1.43) for each 10 μg/m3 increment in ambient PM2.5. Stratified analyses found a lower association among the participants with higher consumption of fruit. We estimated that 22.02% (95% CI: 8.59%, 43.29%) of the diabetes cases could be ascribable to ambient PM2.5. Our finding suggests that PM2.5 exposures could increase the risk of diabetes, and if causal, could be responsible for substantial burden of diabetes among the Chinese elderly; and higher intakes of fruit might reduce the harmful effects of PM2.5, however, due to the limitation of the cross-sectional study design, more studies are warranted to confirm this observation.

Objective Rapid urbanization has led to reduced greenness in many areas, this has been linked to adverse health outcomes. The aim was to determine the association between residential greenness experienced during very early childhood with preschool myopia and astigmatism and to explore the potential mediating role of screen time on any associations. Method Information regarding socio-demographic characteristics, home address, screen time during early childhood, and refraction data from vision screenings of 53,575 preschoolers from Longhua Child Cohort Study were collected via questionnaires. Residential greenness was calculated as the average of satellite-derived Normalized Difference Vegetation Index in buffers of 100, 250, and 500 m around each child's home address. Logistic and linear regression models were used to examine the relationships between residential greenness, screen time, and preschool myopia and astigmatism. Result The mean (SD) age of the 53,575 preschoolers was 5.0 (0.7) years, and 24,849 (46.4%) were girls. A total of 1236 (2.3%) preschoolers had myopia and 5347 (10.0%) had astigmatism. In the adjusted model, a higher neighborhood greenness level within 100 m buffers around the home address was associated with decreased risk of myopia (adjusted odds ratios (AOR): 0.62, 95% confidence interval (CI): 0.38–0.99), and higher neighborhood greenness levels within 100, 250, and 500 m decreased the risk of astigmatism, and their AORs (95% CIs) were 0.55 (0.43–0.70) for 100 m, 0.59 (0.41–0.83) for 250 m, 0.61 (0.42–0.90) for 500 m, respectively. Greater screen time during early childhood increased the risk of myopia (AOR = 1.33) and astigmatism (AOR = 1.23). Reduction in screen time fully mediated the benefits of greater residential greenness on preschool myopia, but partially mediated that on preschool astigmatism (p Conclusion Higher residential greenness reduces the risk of preschool myopia and astigmatism; the benefits of residential greenness were mediated through reduced daily screen time.

Background Both inhalable particles (PM10) and fine particles (PM2.5) are regulated in various countries mainly due to their adverse health effects. However, there is increasing evidence that PM2.5 might be responsible for these effects and coarse particles (PMc) plays little role in adverse health effects, if so, it might be not necessary to monitor PM10. Methods In this study, we conducted a time-series analysis using a generalized additive model to explore the effects of PM2.5, PMc, and PM10 on mortality from ischemic heart disease (IHD) and chronic obstructive pulmonary disease (COPD) in 96 Chinese cities during 2013–2016. The mortality number and attributable fraction were further estimated using the national air quality standard and WHO’s guideline as the reference. Results We observed significant effects of PM2.5 on IHD and COPD mortality; each 10 ug/m3 increase in lag01 PM2.5 was associated with a 0.26% (95% CI: 0.17%, 0.34%) increase in IHD mortality and a 0.19% (95% CI: 0.09%, 0.29%) increase in COPD mortality. We also found significant effects of PMc and PM10 on mortality from IHD and COPD, but the magnitudes of effects were weaker than those of PM2.5. The results were robust when adjusting for co-pollutants and altering model parameters. We further estimated that about 1.27% (95% CI: 0.29%, 2.30%) of IHD mortality and 1.25% (95% CI: 0.08%, 2.46%) of COPD mortality could be attributable to PM2.5 exposure using WHO’s guideline (25 ug/m3) as a reference, corresponding to 15,337 (95% CI: 3,375, 27,842) mortalities from IHD and 5,653 (95% CI: 379, 11,152) COPD mortalities in the 96 cities. Across all of China, almost fifty thousand cases of IHD mortality and twenty thousand cases of COPD mortality might be avoidable if the PM2.5 concentration declined to the WHO guideline. Conclusions Our study indicates that short-term exposure to PM2.5 could be an important risk factor of mortality from IHD and COPD, and substantial cardiopulmonary mortality could be avoidable by reducing daily PM2.5 concentrations. It is nonnegligible to consider the role of PMc in triggering in cardiopulmonary mortality. And it could be necessary to continue monitoring PM10 in the study regions due to the adverse effects of PMc.

Summary Although exposure to air pollution increases the risk of premature mortality and years of life lost (YLL), the effects of daily air quality improvement to the life expectancy of respiratory diseases remained unclear. We applied a generalized additive model (GAM) to assess the associations between daily PM2.5 exposure and YLL from respiratory diseases in 96 Chinese cities during 2013–2016. We further estimated the avoidable YLL, potential gains in life expectancy, and the attributable fraction by assuming daily PM2.5 concentration decrease to the air quality standards of China and World Health Organization. Regional and national results were generated by random-effects meta-analysis. A total of 861,494 total respiratory diseases and 586,962 chronic obstructive pulmonary disease (COPD) caused death from 96 Chinese cities were recorded during study period. Each 10 μg/m3 increase of PM2.5 in 3-day moving average (lag02) was associated with 0.16 (95% CI: 0.08, 0.24) years increment in life expectancy from total respiratory diseases. The highest effect was observed in Southwest region with 0.42 (95% CI: 0.22, 0.62) years increase in life expectancy. By attaining the WHO's Air Quality Guidelines, we estimated that an average of 782.09 (95% CI: 438.29, 1125.89) YLLs caused by total respiratory death in each city could be avoided, which corresponded to 1.15% (95% CI: 0.67%, 1.64%) of the overall YLLs, and 0.12 (95% CI: 0.07, 0.17) years increment in life expectancy. The results of COPD were generally consistent with total respiratory diseases. Our findings indicate that reduction in daily PM2.5 concentrations might lead to longer life expectancy from respiratory death., Graphical Abstract, Public Summary • This is a nationwide time-series study in 96 Chinese cities • PM2.5 level was associated with increased risk of respiratory death • PM2.5 level was associated with increased years of life lost of respiratory death • Daily PM2.5 reduction might lead to longer life expectancy from respiratory death

BACKGROUND: Air pollution has been associated with various health outcomes. Its effect on hand-grip strength, a measurement of the construct of muscle strength and health status, remains largely unknown. METHODS: We used the survey data from 31,209 adults ≥ 50 years of age within Wave 1 of the Study on Global AGEing and Adult Health in six low- and middle-income countries. The outdoor concentration of fine particulate matter pollution (PM2.5) was estimated using satellite data. Domestic fuel type and ventilation were used as indicators of indoor air pollution. We used multilevel linear regression models to examine the association between indoor and outdoor air pollution and hand-grip strength, as well as the potential effect modifiers. RESULTS: We found inverse associations between both indoor and outdoor air pollution and hand-grip strength. Each 10 μg/m3 increase in 3 years' averaged concentrations of outdoor PM2.5 corresponded to 0.70 kg (95% CI: -1.26, -0.14) lower hand-grip strength; and compared with electricity/liquid/gas fuel users, those using solid fuels had lower hand-grip strength (β = -1.25, 95% CI: -1.74, -0.75). However, we did not observe a statistically significant association between ventilation and hand-grip strength. We further observed that urban residents and those having a higher education level had a higher association between ambient PM2.5 and hand-grip strength, and men, young participants, smokers, rural participants, and those with lower household income had higher associations between indoor air pollution and hand-grip strength. CONCLUSION: This study suggests that both indoor and outdoor air pollution might be important risk factors of poorer health and functional status as indicated by hand-grip strength.

Maternal blood glucose level is associated with fetal growth, therefore, its role in the associations between air pollution and birth weight deserves investigation. We examined the mediation effect of maternal blood glucose on the associations between maternal air pollution exposure and birth weight. A total of 10,904 pregnant women in Foshan, China during 2015–2019 were recruited. Oral glucose tolerance test (OGTT) was administered to each participant after late trimester 2. Air pollution data at the monitoring stations in residential districts was used to estimate exposures of each participant during trimester 1 and trimester 2. Mixed-effects linear models were used to estimate the associations between air pollution and birth weight. After controlling for ten covariates, the direct effect of PM2.5 and SO2 (each 10 μg/m3 increment) on birth weight was −15.7 g (95% CI: −29.4, −4.8 g) and −83.6 g (95% CI: −134.8, −33.0 g) during trimester 1. The indirect effect of PM2.5 and SO2 (each 10 μg/m3 increment) on birth weight by increasing maternal fasting glucose level was 6.6 g (95% CI: 4.6, 9.1 g) and 22.0 g (95% CI: 4.1, 44.0 g) during trimester 1. Our findings suggest that air pollution might affect the birth weight through direct and indirect pathway, and the indirect effect might be mediated by maternal blood glucose.

Although myopia has been largely ignored among the elderly population, there is an increased risk of myopia with advancing age. Ambient air pollution is one potential contributor to vision impairments, but few epidemiological studies have demonstrated such an association. This cross-sectional survey collected the information of 33,626 subjects aged ≥50 years in six developing countries during 2007–2010. Myopia was identified based on questions related to symptoms of myopia. The annual concentrations of fine particulate matter (PM2.5) and ozone (O3) were estimated with the satellite data and chemical transport model. We examined the associations between the two pollutants and myopia using mixed-effect Poisson regression models with robust variance estimation (sandwich estimation). We observed J-shaped associations between the two pollutants and myopia, and identified 12 and 54 μg/m3 as the threshold concentrations. The adjusted prevalence ratio was 1.12 (95% CI: 1.05, 1.21) and 1.26 (95% CI: 1.14, 1.38) for each standard deviation (SD) increase in PM2.5 and O3 concentrations above their threshold, respectively. In addition, the interaction analysis suggested a synergistic interaction of these two pollutants on myopia in the additive model, with a synergistic index of 1.81 (Bootstrapping 95% CI: 0.92, 4.94). Our results indicate that long-term exposures to PM2.5 and O3 might be important environmental risk factors of myopia in the elderly, and suggest that more efforts should be taken to reduce airborne PM2.5 and O3 levels to protect vision health.

Background The potential impacts of daily ambient fine particulate pollution (PM2.5) exposure on year of life lost (YLL) due to ischemic heart diseases (IHD) remain uncertain. We aimed to estimate the improvement in IHD-related life expectancy by attaining the daily air quality standards of ambient PM2.5 in China. Methods and results This study was based on daily mortality data covering 96 Chinese cities from 2013 to 2016. Regional- and national-associations between IHD-related YLLs and daily PM2.5 were estimated by generalized additive models. We further evaluated the IHD-related avoidable YLLs with an assumption that the daily PM2.5 was below the ambient air quality standards of World Health Organization (WHO) and China, and calculated the improvement of life expectancy by dividing the avoidable YLLs by the overall number of IHD mortality. We totally recorded 1,485,140 IHD deaths from 2013 to 2016. At the national level, we found a positive association between IHD-related YLLs and daily PM2.5. Per 10 μg/m3 increment of four-day averaged ambient PM2.5 related to an increase of 0.40 IHD-related YLLs (95% CI: 0.28, 0.51). By achieving the WHO's air quality guideline, we estimated that an averaged number of 1346.94 (95% CI: 932.61, 1761.27) YLLs can be avoided for the IHD deaths in each city. On average, the life expectancy can be improved by 0.15 years (95% CI: 0.11, 0.19) for each death. Conclusions Our study provides a nationwide picture of the life expectancy improvements by reaching the daily PM2.5 standards in China, indicating that people can live longer in an environment with higher air quality.

Background Though the conjunctiva are directly contacting with the atmospheric environment, the association between air pollution and conjunctival disease has not been well documented. Objective To explore the association between ambient nitrogen dioxide (NO2) and daily outpatient visits for cause-specific conjunctivitis in Jinan, China. Methods Daily concentrations of air pollution were obtained from the air quality sharing platform of China, and daily outpatient visits for conjunctivitis were collected from Qilu Hospital. The association between daily NO2 level and outpatient visits for conjunctivitis was examined by a generalized additive Poisson model, and stratified analyses by sex, age and season were further performed. Results A total of 42,123 outpatient visits for conjunctivitis were recorded during 2014–2019, including 8504 infective conjunctivitis, 6429 allergic conjunctivitis and 27,190 unspecified conjunctivitis. Each 10 μg/m3 increase in NO2 was associated with a 1.00% (95% CI: 0.13%, 1.87%) increment in daily outpatient visits for conjunctivitis. Significant associations between NO2 and conjunctivitis were observed in the female population [excess risk, ER = 1.09% (95% CI: 0.05%, 2.15%)], in people aged 18–65 years [ER = 1.15% (95% CI: 0.15%, 2.15%)] and in cold season [ER = 1.67% (95% CI: 0.58%, 2.77%)]. Moreover, we also found significant associations of NO2 with infective conjunctivitis [ER = 2.60% (95% CI: 0.69%, 4.54%)], but not with allergic conjunctivitis [ER = −0.43% (95% CI: −2.38%, 1.56%)]and unspecified conjunctivitis [ER = 0.16% (95% CI: −0.96%, 1.29%)]. Conclusion This study suggests that short-term exposure to NO2 might induce conjunctivitis, and air pollution control measures should be encouraged to keep ocular surface healthy.

Background To investigate the effects of air pollution exposure during pregnancy on the indicators of glucose homeostasis and gestational diabetes mellitus (GDM). Methods We conducted a birth cohort study in Foshan, China during 2015–2019. Oral glucose tolerance test (OGTT) was administered to each participant during pregnancy. GDM was defined according to the International Association of Diabetes and Pregnancy Study Groups criteria (IADPSG). Air pollutant (fine particulate matter (PM2.5), particulate matter with an aerodynamic diameter of 10 μm or less (PM10), sulfate dioxide (SO2), nitrogen dioxide (NO2) and ozone (O3)) concentrations from the air monitoring stations in Foshan were used to estimate individual air pollutant exposure during the first two trimesters. Linear and logistic regression models were employed to estimate the associations between air pollution exposure during the first two trimesters and OGTT glucose levels and GDM. Results Of 12,842 pregnant women, 3055 (23.8%) had GDM. A 10 μg/m3 increase in PM2.5, PM10 and SO2 during trimester 1, trimester 2 and two trimesters were associated with 0.07 mmol/L to 0.29 mmol/L increment in OGTT-fasting glucose levels in single-pollutant model. A 10 μg/m3 increase in NO2 and O3 during two trimesters were associated with 0.15 mmol/L and 0.12 mmol/L decrease in OGTT-fasting glucose in single-pollutant model. However, no significant or weaker effects of O3 during two trimesters on OGTT-fasting glucose were observed in two-pollutant models. Moreover, exposure to PM2.5, PM10 and SO2 were associated with increased risk of GDM in both single- and two-pollutant models. Conclusions Our study suggests PM2.5, PM10 and SO2 exposure during the first two trimesters might increase the risk of GDM.

Background Previous research has reported the effects of long-term fine particulate matter (PM2.5) pollution on years of life lost (YLL), but these effects may not represent the full impact. This study aims to estimate potential benefits in life time from adhering to daily ambient PM2.5 concentration standards/guidelines. Methods This study evaluated the relationship between daily ambient PM2.5 level and YLL using a two-stage approach with generalized additive models and meta-analysis. Potential life expectancy gains were then estimated by presuming that daily PM2.5 levels were in compliance with the Chinese and WHO standards. In addition, the attributable fraction of YLL due to excess PM2.5 exposure was also calculated. Results During 2013–2016, 459,468 non-accidental deaths were recorded in the six cities of Pearl River Delta, China. Each 10 μg/m3 increment in four-day average (lag03) level of PM2.5 was related to an increment of 13.31 [95% confidence interval (CI): 5.74, 20.87] years of life lost. Implementation of the WHO guidelines might avoid 180,980.83 YLLs (95% CI: 78,116.07, 283,845.60), which corresponded to 0.39 (95% CI: 0.17, 0.62) years of increased life time per death. Additionally, an estimated 0.15% (95% CI: 0.06%, 0.23%) or 2.04% (95% CI: 0.88%, 3.20%) of YLLs could be attributed to PM2.5 exposures higher than the Chinese or WHO guidelines, respectively. Conclusions This study suggests that people might live longer by controlling daily PM2.5 concentration and highlights the need to adopt stricter standards in China.

Objectives Prenatal exposure to air pollutant has been associated with congenital heart defect (CHD). However, no study has investigated this effect in pre-pregnancy overweighted women. This study aimed to evaluate gestational exposure to particulate pollutant (PM2.5) and gaseous air pollutants (O3 and NO2) on the risk of CHD, and explore the potential effect modifiers including maternal age, pre-pregnancy BMI and pregestational diseases. Methods In this birth cohort study, a total of 63,213 pregnant women in Foshan, China were initially recruited and followed from their first hospital visit for pregnancy to delivery during 2015–2019. CHD cases were confirmed by the records in hospital- and population- based birth defect surveillance systems. Air pollutant exposures were estimated by the daily concentrations measured in air monitoring stations in each participant's residential county. Mixed-effects regression models, adjusted for potential confounding factors were applied to estimate the associations between air pollutant and CHD during the first three months of the pregnancy. Results A total of 985 (1.6%) newborns were identified as CHD cases. For each 10 μg/m3 increase in ambient O3 during the 1st month, the OR values for CHD were 1.03 (95% CI: 0.94, 1.13) in pre-pregnancy normal weighted women and 1.24 (95% CI: 1.01, 1.53) in pre-pregnancy overweighted women. For each 10 μg/m3 increase in NO2 during the 3rd month, the OR values for CHD were 1.09 (95% CI: 1.01, 1.18) in pre-pregnancy normal weighted women and 1.27 (95% CI: 1.07, 1.51) in pre-pregnancy overweighted women. No significant associations were found between PM2.5 exposure and CHD in our analysis. Conclusions This study demonstrates that gaseous air pollutants (O3 and NO2) exposure during the cardiac embryogenesis period is associated with an increased risk of CHD, particularly for pre-pregnancy overweighted women.

Background Maternal exposure to various air pollutants is one crucial contributor to adverse birth outcomes, however, the effects of ozone (O3) exposure have remained largely unknown, especially attributable burden in different exposure windows. Methods We performed a birth cohort study in nine Chinese cities in Guangdong Province during 2014–2017. The mothers were included in this study at their first time hospital visits for pregnancy in the nine cities, and followed up till the delivery. Air pollution exposure of each participant was estimated using the daily data from air monitoring stations in the mother's residential district. The status of low birth weight (LBW) and preterm birth (PTB) was ascertained based on standard criteria and collected from the electronic medical record. We applied a Cox regression model to estimate the associations and the attributable burden. Results Among the 1,455,026 mother-and-live-birth pairs, 64,028 (4.40%) were PTB, and 57,618 (3.96%) were LBW. After adjustment for potential confounders, the hazard ratios for each 10 μg/m3 increase in O3 concentrations during trimester 1, trimester 2, one week prior and four weeks prior were 1.025 (95% CI: 1.020, 1.030), 1.033 (95% CI: 1.028, 1.039), 1.013 (95% CI: 1.010, 1.017) and 1.016 (95% CI: 1.011, 1.020) for PTB, 1.035 (95% CI: 1.030, 1.040), 1.035 (95% CI: 1.029, 1.041), 1.013 (95% CI: 1.009, 1.017) and 1.016 (95% CI: 1.012, 1.021) for LBW, respectively. The estimated attributable fractions at one week prior to delivery were 0.86% (95% CI: 0.39%, 9.26%) of PTB and 0.87% (95% CI: 0.60%, 1.14%) of LBW. Conclusions This study indicates that maternal exposure to O3 might lead to increased risk of PTB and LBW, and is responsible for non-negligible burden of PTB and LBW in the study region.

Substantial evidence has linked short-term exposure to ambient fine particulate matter (PM2.5) with increased cardiovascular mortality, however, the specific chemical constituent and emission source responsible for this effect remained largely unclear. A time series Poisson model was employed to quantify the association of cardiovascular mortality with two sets of shipping pollution emission: nickel (Ni), vanadium (V) (the indices of shipping emission) and estimated shipping emission using a source apportionment approach in Guangzhou, China in 2014. We observed that Ni, V, and estimated shipping emission in PM2.5 were associated with increased cardiovascular mortality, an inter-quartile range (IQR) increase in lag2 Ni was associated with 4.60% (95% CI: 0.14%, 9.26%) increase in overall cardiovascular mortality, and 13.35% (95% CI: 5.54%, 21.75%) increase in cerebrovascular mortality; each IQR increase of lag1 V was correlated with 6.01% (95% CI: 1.83%, 10.37%) increase in overall cardiovascular mortality, and 11.02% (95% CI: 3.15%, 19.49%) increase in cerebrovascular mortality; and each IQR increase in lag1 shipping emission was associated with 5.55% (95% CI: 0.78%, 10.54%) increase in overall cardiovascular mortality, and 10.39% (95% CI: 1.43%, 20.14%) increase in cerebrovascular mortality. The results remained robust to adjustment for PM2.5 mass and gaseous air pollutants. This study suggests that shipping emission is an important detrimental factor of cardiovascular mortality, and should be emphasized in air pollution control and management in order to protect the public health in Guangzhou, China.

Although ambient air pollution has been consistently associated with morbidity and mortality of stroke, there is limited evidence on whether the control of air pollution would associate with a reduced risk of stroke. The citywide air pollution controlling measures during the 2010 Asian Games in Guangzhou provided such an opportunity to answer this question. We collected daily data on the concentrations of air pollutants and mortality from ischemic and hemorrhagic stroke, and compared them for 51 intervention days in 2010 with the corresponding days in 2006–2009 and 2011 (reference period). Poisson-based interrupted time series analysis was employed to estimate the relative risk (RR) and 95% confidence interval (CI). The daily mean concentrations of PM10 (particles with an aerodynamic diameter smaller than 10 μm) was 88.64 μg/m3 during the reference period, and 80.47 μg/m3 during the intervention period. Daily mortality number of total stroke, ischemic and hemorrhagic stroke decreased from 3.67, 2.00 and 1.67 during the reference period, to 3.00, 1.76 and 1.24 during the intervention period; the corresponding RR was 0.79 (95% CI: 0.66–0.94), 0.87 (95% CI: 0.69–1.11) and 0.69 (95% CI: 0.52–0.91), respectively. Our findings show that ambient air pollution controlling measures during the 2010 Asian Games in Guangzhou were associated with a decreased risk of stroke mortality, which suggests a need to reduce air pollution to improve public health.