Associations of long-term exposure to ambient PM2.5 with mortality in Chinese adults: A pooled analysis of cohorts in the China-PAR project

The joint impact of PM2.5 constituents on the risk of cerebrovascular diseases hospitalization: A large community-based cohort study

Air pollution poses significant health risks to urban areas, with limited focus on the chronic association of PM2.5 and its constituents on cerebrovascular diseases (CERs), especially regarding the joint associations. This study explores the individual and joint associations between PM2.5 constituents and CER hospitalization risks through a cohort analysis of 36,271 adults in the Pearl River Delta, South China, from 2015 to 2020. Cox proportional hazards regression and quantile-based g-computation models were used to quantify the individual and joint associations of annual mean concentrations of PM2.5 constituents with hospitalization for CERs. 1151 participants were hospitalized due to CERs during the five-year follow-up period. Joint associations analyses identified that one quartile increase in co-exposure may result in hazard ratios of 1.530 (1.441-1.623), 1.840 (1.710-1.980), and 1.609 (1.491-1.737) for CERs, total, and ischemic stroke hospitalization, respectively. The adverse effect was primarily driven by organic matter and chlorine. Men, those with a history of tobacco or alcohol use or with low residential greenness, were more susceptible to CERs hospitalization following PM2.5 constituents co-exposure. Upcoming strategies should focus on monitoring and regulating PM2.5 constituents, encouraging healthy lifestyles, and enhancing urban greenery.

Long-term exposure to PM2.5 and mortality: a national health insurance cohort study

BACKGROUND

Previous studies with large data have been widely reported that exposure to fine particulate matter (PM2.5) is associated with all-cause mortality; however, most of these studies adopted ecological time-series designs or have included limited study areas or individuals residing in well-monitored urban areas. However, nationwide cohort studies including cause-specific mortalities with different age groups were sparse. Therefore, this study examined the association between PM2.5 and cause-specific mortality in South Korea using the nationwide cohort.

METHODS

A longitudinal cohort with 187 917 National Health Insurance Service-National Sample Cohort participants aged 50-79 years in enrolment between 2002 and 2019 was used. Annual average PM2.5 was collected from a machine learning-based ensemble model (a test R2 = 0.87) as an exposure. We performed a time-varying Cox regression model to examine the association between long-term PM2.5 exposure and mortality. To reduce the potential estimation bias, we adopted generalized propensity score weighting method.

RESULTS

The association with long-term PM2.5 (2-year moving average) was prominent in mortalities related to diabetes mellitus [hazard ratio (HR): 1.03 (95% CI: 1.01, 1.06)], circulatory diseases [HR: 1.02 (95% CI: 1.00, 1.03)] and cancer [HR: 1.01 (95% CI: 1.00, 1.02)]. Meanwhile, circulatory-related mortalities were associated with a longer PM2.5 exposure period (1 or 2-year lags), whereas respiratory-related mortalities were associated with current-year PM2.5 exposure. In addition, the association with PM2.5 was more evident in people aged 50-64 years than in people aged 65-79 years, especially in heart failure-related deaths.

CONCLUSIONS

This study identified the hypothesis that long-term exposure to PM2.5 is associated with mortality, and the association might be different by causes of death. Our result highlights a novel vulnerable population: the middle-aged population with risk factors related to heart failure.

Exposure to submicron particulate matter and long-term survival: Cross-cohort analysis of 3 Chinese national surveys

BACKGROUND

Cohort evidence linking increased mortality with airborne fine particulate matter (PM2.5, particulate matter [PM] with aerodynamic diameter ≤2.5 μm) exposure was extensively validated worldwide. Nevertheless, long-term survival associated with submicron particulate matter (PM1, PM with aerodynamic diameter ≤1 μm) exposure remained largely unstudied, particularly in highly exposed populations.

METHODS

We performed a population-based investigation involving 86844 adults aged 16+ years from 3 national dynamic cohorts spanning from 2005 to 2018. Residential annual exposure to PM1 and PM2.5 was assigned for each follow-up year using satellite-derived spatiotemporal estimates at a 1-km2 resolution. The concentration of PM1-2.5 (PM with aerodynamic diameter between 1 and 2.5 μm) was calculated by subtracting PM1 from PM2.5. Time-independent Cox proportional hazards regression models were applied to assess the associations of all-cause mortality with long-term exposure to size-specific particles. To investigate the effect of PM1 on PM2.5-mortality associations, we categorized participants into low, medium, and high groups based on PM1/PM2.5 ratio and examined the risk of PM2.5-associated mortality in each stratum. Effect modifications were checked via subgroup analyses.

RESULTS

A total of 18722 deaths occurred during 497069.2 person-years of follow-up (median 5.7 years). Participants were exposed to an average annual concentration of 31.8 μg/m³ (range: 7.6-66.8 μg/m³) for PM1, 56.3 μg/m³ (range: 19.8-127.2 μg/m³) for PM2.5, and 24.5 μg/m³ (range: 7.3-60.3 μg/m³) for PM1-2.5. PM1, PM2.5, and PM1-2.5 were consistently associated with elevated mortality risks, with a hazard ratio (HR) of 1.029 (95% confidence interval [CI]: 1.013-1.046), 1.014 (95% CI: 1.005-1.023), and 1.019 (95% CI: 1.001-1.038) for each 10-μg/m3 increase in exposure, respectively. Compared with low (HR = 0.986, 95% CI: 0.967-1.004) and medium (HR = 1.015, 95% CI: 1.002-1.029) PM1/PM2.5 ratio groups, PM2.5-related risk of mortality was more pronounced in high PM1/PM2.5 ratio stratum (HR = 1.041, 95% CI: 1.019-1.064). Greater risks of mortality associated with size-specific particles were found among the elderly (>80 years old), southeastern participants, and those living in warmer areas.

CONCLUSIONS

This study demonstrated that long-term exposure to PM1, PM2.5, and PM1-2.5 was associated with heightened mortality, and PM1 may play a predominant role in PM2.5-induced risk. Our results emphasized the population health implications of establishing ambient PM1 air quality guidelines to mitigate the burden of premature mortality stemming from particulate air pollution.

Key factors in epidemiological exposure and insights for environmental management: Evidence from meta-analysis

In recent years, the precision of exposure assessment methods has been rapidly improved and more widely adopted in epidemiological studies. However, such methodological advancement has introduced additional heterogeneity among studies. The precision of exposure assessment has become a potential confounding factors in meta-analyses, whose impacts on effect calculation remain unclear. To explore, we conducted a meta-analysis to integrate the long- and short-term exposure effects of PM2.5, NO2, and O3 on all-cause, cardiovascular, and respiratory mortality in the Chinese population. Literature was identified through Web of Science, PubMed, Scopus, and China National Knowledge Infrastructure before August 28, 2023. Sub-group analyses were performed to quantify the impact of exposure assessment precisions and pollution levels on the estimated risk. Studies achieving merely city-level resolution and population exposure are classified as using traditional assessment methods, while those achieving sub-kilometer simulations and individual exposure are considered finer assessment methods. Using finer assessment methods, the RR (under 10 μg/m3 increment, with 95% confidence intervals) for long-term NO2 exposure to all-cause mortality was 1.13 (1.05-1.23), significantly higher (p-value = 0.01) than the traditional assessment result of 1.02 (1.00-1.03). Similar trends were observed for long-term PM2.5 and short-term NO2 exposure. A decrease in short-term PM2.5 levels led to an increase in the RR for all-cause and cardiovascular mortality, from 1.0035 (1.0016-1.0053) and 1.0051 (1.0021-1.0081) to 1.0055 (1.0035-1.0075) and 1.0086 (1.0061-1.0111), with weak between-group significance (p-value = 0.13 and 0.09), respectively. Based on the quantitative analysis and literature information, we summarized four key factors influencing exposure assessment precision under a conceptualized framework: pollution simulation resolution, subject granularity, micro-environment classification, and pollution levels. Our meta-analysis highlighted the urgency to improve pollution simulation resolution, and we provide insights for researchers, policy-makers and the public. By integrating the most up-to-date epidemiological research, our study has the potential to provide systematic evidence and motivation for environmental management.

Predicting particulate matter, nitrogen dioxide, and ozone across Great Britain with high spatiotemporal resolution based on random forest models

In Great Britain, limited studies have employed machine learning methods to predict air pollution especially ozone (O3) with high spatiotemporal resolution. This study aimed to address this gap by developing random forest models for four key pollutants (fine and inhalable particulate matter [PM2.5 and PM10], nitrogen dioxide [NO2] and O3) by integrating multiple-source predictors at a daily level and 1-km resolution. The out-of-bag R2 (root mean squared error, RMSE) between predictions from models and measurements from monitoring stations in 2006-2013 was 0.85 (3.63 μg/m3) for PM2.5, 0.77 (6.00 μg/m3) for PM10, 0.85 (9.71 μg/m3) for NO2, and 0.85 (9.39 μg/m3) for maximum daily 8-h average (MDA8) O3 at daily level, and the predicting accuracy was higher at monthly and annual level. The high-resolution predictions captured characterized spatiotemporal patterns of the four pollutants. Higher concentrations of PM2.5, PM10, and NO2 were distributed in densely populated southern regions of Great Britain while O3 showed an inverse spatial pattern in general, which could not be fully depicted by monitoring stations. Therefore, predictions produced in this study could improve exposure assessment with less exposure misclassification and flexible exposure windows for future epidemiological studies to investigate the impact of air pollution across Great Britain.

Burden of cardiovascular disease attributed to air pollution: a systematic review

BACKGROUND

Cardiovascular diseases (CVDs) are estimated to be the leading cause of global death. Air pollution is the biggest environmental threat to public health worldwide. It is considered a potentially modifiable environmental risk factor for CVDs because it can be prevented by adopting the right national and international policies. The present study was conducted to synthesize the results of existing studies on the burden of CVDs attributed to air pollution, namely prevalence, hospitalization, disability, mortality, and cost characteristics.

METHODS

A systematic search was performed in the Scopus, PubMed, and Web of Science databases to identify studies, without time limitations, up to June 13, 2023. Exclusion criteria included prenatal exposure, exposure to indoor air pollution, review studies, conferences, books, letters to editors, and animal and laboratory studies. The quality of the articles was evaluated based on the Agency for Healthcare Research and Quality Assessment Form, the Newcastle-Ottawa Scale, and Drummond Criteria using a self-established scale. The articles that achieved categories A and B were included in the study.

RESULTS

Of the 566 studies obtained, based on the inclusion/exclusion criteria, 92 studies were defined as eligible in the present systematic review. The results of these investigations supported that chronic exposure to various concentrations of air pollutants, increased the prevalence, hospitalization, disability, mortality, and costs of CVDs attributed to air pollution, even at relatively low levels. According to the results, the main pollutant investigated closely associated with hypertension was PM2.5. Furthermore, the global DALY related to stroke during 2016-2019 has increased by 1.8 times and hospitalization related to CVDs in 2023 has increased by 8.5 times compared to 2014.

CONCLUSION

Ambient air pollution is an underestimated but significant and modifiable contributor to CVDs burden and public health costs. This should not only be considered an environmental problem but also as an important risk factor for a significant increase in CVD cases and mortality. The findings of the systematic review highlighted the opportunity to apply more preventive measures in the public health sector to reduce the footprint of CVDs in human society.

Health benefits of vehicle electrification through air pollution in Shanghai, China

Vehicle electrification has been recognized for its potential to reduce emissions of air pollutants and greenhouse gases in China. Several studies have estimated how national-level policies of electric vehicle (EV) adoption might bring very large environmental and public health benefits from improved air quality to China. However, large-scale adoption is very costly, some regions derive more benefits from large-scale EV adoption than others, and the benefits of replacing internal combustion engines in specific cities are less known. Therefore, it is important for policymakers to design incentives based on regional characteristics - especially for megacities like Shanghai - which typically suffer from worse air quality and where a larger population is exposed to emissions from vehicles. Over the past five years, Shanghai has offered substantial personal subsidies for passenger EVs to accelerate its electrification efforts. Still, it remains uncertain whether EV benefits justify the strength of incentives. The purpose of our study is to evaluate the health and climate benefits of replacing light-duty gasoline vehicles (ICEVs) with battery EVs in the city of Shanghai. We assess health impacts due to ICEV emissions of primary fine particulate matter, NOx, and volatile organic compounds, and to powerplant emissions of NOx and SO2 due to EV charging. We incorporate climate benefits from reduced greenhouse gas emissions based on existing research. We find that the benefit of replacing the average ICEV with an EV in Shanghai is US$6400 (2400-14,700), with health impacts of EVs about 20 times lower than the average ICEV. Larger benefits ensue if older ICEVs are replaced, but replacing newer China ICEVs also achieves positive health benefits. As Shanghai plans to stop providing personal subsidies for EV purchases in 2024, our results show that EVs achieve public health and climate benefits and can help inform policymaking strategies in Shanghai and other megacities.

Long-term ozone exposure and all-cause mortality: Cohort evidence in China and global heterogeneity by region

BACKGROUND

Cohort evidence linking long-term ozone (O3) exposure to mortality remained largely mixed worldwide and was extensively deficient in densely-populated Asia. This study aimed to assess the long-term effects of O3 exposure on all-cause mortality among Chinese adults, as well as to examine potential regional heterogeneity across the globe.

METHODS

A national dynamic cohort of 42153 adults aged 16+ years were recruited from 25 provinces across Chinese mainland and followed up during 2010-2018. Annual warm-season (April-September) O3 and year-round co-pollutants (i.e., nitrogen dioxide [NO2] and fine particulate matter [PM2.5]) were simulated through validated spatial-temporal prediction models and were assigned to each enrollee in each calendar year. Cox proportional hazards models with time-varying exposures were employed to assess the O3-mortality association. Concentration-response (C-R) curves were fitted by natural cubic spline function to investigate the potential nonlinear association. Both single-pollutant model and co-pollutant models additionally adjusting for PM2.5 and/or NO2 were employed to examine the robustness of the estimated association. The random-effect meta-analysis was adopted to pool effect estimates from the current and prior population-based cohorts (n = 29), and pooled C-R curves were fitted through the meta-smoothing approach by regions.

RESULTS

The study population comprised of 42153 participants who contributed 258921.5 person-years at risk (median 6.4 years), of whom 2382 death events occurred during study period. Participants were exposed to an annual average of 51.4 ppb (range: 22.7-74.4 ppb) of warm-season O3 concentration. In the single-pollutant model, a significantly increased hazard ratio (HR) of 1.098 (95% confidence interval [CI]: 1.023-1.179) was associated with a 10-ppb rise in O3 exposure. Associations remained robust to additional adjustments of co-pollutants, with HRs of 1.099 (95% CI: 1.023-1.180) in bi-pollutant model (+PM2.5) and 1.093 (95% CI: 1.018-1.174) in tri-pollutant model (+PM2.5+NO2), respectively. A J-shaped C-R relationship was identified among Chinese general population, suggesting significant excess mortality risk at high ozone exposure only. The combined C-R curves from Asia (n = 4) and North America (n = 17) demonstrated an overall increased risk of all-cause mortality with O3 exposure, with pooled HRs of 1.124 (95% CI: 0.966-1.307) and 1.023 (95% CI: 1.007-1.039) per 10-ppb rise, respectively. Conversely, an opposite association was observed in Europe (n = 8, HR: 0.914 [95% CI: 0.860-0.972]), suggesting significant heterogeneity across regions (P < 0.01).

CONCLUSIONS

This study provided national evidence that high O3 exposure may curtail long-term survival of Chinese general population. Great between-region heterogeneity of pooled O3-mortality was identified across North America, Europe, and Asia.

Effects of long-term exposure to ambient fine particulate air pollution on all-cause mortality in Taiwan

According to the US Environmental Protection Agency's Integrated Science Assessment (ISA), there is a causal relationship between fine particulate matter (PM2.5) exposure and increased mortality rates. A similar association was also reported by the International Agency for Research on Cancer (IARC). While many studies are available on this relationship between PM exposure and elevated mortality frequency in Europe and North America, there are limited investigations in Asia. Thus, the aim of this study was to perform an ecological investigation to determine the relationship between exposure to ambient PM2.5 levels and all-cause mortality in 66 in Taiwan municipalities. To undertake this investigation, annual PM2.5 levels and age-standardized all-cause mortality rates were calculated for male and female residents of these areas from 2010 to 2020. Weighted-multiple regression analyses were used to obtain adjusted risk ratio (RR) controlling for possible confounding by urbanization level, physician density, and annual mean household income. Annual PM2.5 levels of each municipality were divided into tertiles. Data demonstrated that men residing in areas with intermediate tertile PM2.5 levels (21.06 to 27.29 µg/m3) and the highest tertiles levels (27.30-33.11 µg/m3) exhibited adjusted RRs of 1.06 (95% CI = 1.03-1.08) and 1.13 (95% CI = 1.10-1.16), respectively. Women in these locations displayed a similar risk, 1.03 (0.99-1.06) and 1.07 (1.04-1.11), respectively. These findings indicate that ambient exposure to PM2.5 increased risk for all-cause mortality rates in both men and women in Taiwan during this time period.

Associations of long-term fine particulate matter exposure with all-cause and cause-specific mortality: results from the ChinaHEART project

Background

The chronic effects of fine particulate matter (PM2.5) at high concentrations remains uncertain. We aimed to examine the relationship of long-term PM2.5 exposure with all-cause and the top three causes of death (cardiovascular disease [CVD], cancer, and respiratory disease), and to analyze their concentration-response functions over a wide range of concentrations.

Methods

We enrolled community residents aged 35-75 years from 2014 to 2017 from all 31 provinces of the Chinese Mainland, and followed them up until 2021. We used a long-term estimation dataset for both PM2.5 and O3 concentrations with a high spatiotemporal resolution to assess the individual exposure, and used Cox proportional hazards models to estimate the associations between PM2.5 and mortalities.

Findings

We included 1,910,923 participants, whose mean age was 55.6 ± 9.8 years and 59.4% were female. A 10 μg/m3 increment in PM2.5 exposure was associated with increased risk for all-cause death (hazard ratio 1.02 [95% confidence interval 1.012-1.028]), CVD death (1.024 [1.011-1.037]), cancer death (1.037 [1.023-1.052]), and respiratory disease death (1.083 [1.049-1.117]), respectively. Long-term PM2.5 exposure nonlinearly related with all-cause, CVD, and cancer mortalities, while linearly related with respiratory disease mortality.

Interpretation

The overall effects of long-term PM2.5 exposure on mortality in the high concentration settings are weaker than previous reports from settings of PM2.5 concentrations < 35 μg/m³. The distinct concentration-response relationships of CVD, cancer, and respiratory disease mortalities could facilitate targeted public health efforts to prevent death caused by air pollution.

Funding

The Chinese Academy of Medical Sciences Innovation Fund for Medical Science, the National High Level Hospital Clinical Research Funding, the Ministry of Finance of China and National Health Commission of China, the 111 Project from the Ministry of Education of China.

Research progress on the effects of gut microbiome on lung damage induced by particulate matter exposure

Air pollution is one of the top five causes of death in the world and has become a research hotspot. In the past, the health effects of particulate matter (PM), the main component of air pollutants, were mainly focused on the respiratory and cardiovascular systems. However, in recent years, the intestinal damage caused by PM and its relationship with gut microbiome (GM) homeostasis, thereby affecting the composition and function of GM and bringing disease burden to the host lung through different mechanisms, have attracted more and more attention. Therefore, this paper reviews the latest research progress in the effect of PM on GM-induced lung damage and its possible interaction pathways and explores the potential immune inflammatory mechanism with the gut-lung axis as the hub in order to understand the current research situation and existing problems, and to provide new ideas for further research on the relationship between PM pollution, GM, and lung damage.

Long-Term Exposure to PM2.5 and Mortality: A Cohort Study in China

We investigated the association of long-term exposure to atmospheric PM2.5 with non-accidental and cause-specific mortality in Yinzhou, China. From July 2015 to January 2018, a total of 29,564 individuals aged ≥ 40 years in Yinzhou were recruited for a prospective cohort study. We used the Cox proportional-hazards model to analyze the relationship of the 2-year average concentration of PM2.5 prior to the baseline with non-accidental and cause-specific mortality. The median PM2.5 concentration was 36.51 μg/m3 (range: 25.57-45.40 μg/m3). In model 4, the hazard ratios per 10 μg/m3 increment in PM2.5 were 1.25 (95%CI: 1.04-1.50) for non-accidental mortality and 1.38 (95%CI:1.02-1.86) for cardiovascular disease mortality. We observed no associations between PM2.5 and deaths from respiratory disease or cancer. In the subgroup analysis, interactions were observed between PM2.5 and age, as well as preventive measures on hazy days. The observed association between long-term exposure to atmospheric PM2.5 at a relatively moderate concentration and the risk of non-accidental and cardiovascular disease mortality among middle-aged and elderly Chinese adults could provide evidence for government decision-makers to revise environmental policies towards a more stringent standard.

Excess mortality associated with high ozone exposure: A national cohort study in China

Emerging epidemiological studies suggest that long-term ozone (O₃) exposure may increase the risk of mortality, while pre-existing evidence is mixed and has been generated predominantly in North America and Europe. In this study, we investigated the impact of long-term O₃ exposure on all-cause mortality in a national cohort in China. A dynamic cohort of 20882 participants aged ≥40 years was recruited between 2011 and 2018 from four waves of the China Health and Retirement Longitudinal Study. A Cox proportional hazard regression model with time-varying exposures on an annual scale was used to estimate the mortality risk associated with warm-season (April-September) O₃ exposure. The annual average level of participant exposure to warm-season O₃ concentrations was 100 μg m^-3 (range: 61-142 μg m^-3). An increase of 10 μg m^-3 in O₃ was associated with a hazard ratio (HR) of 1.18 (95% confidence interval [CI]: 1.13-1.23) for all-cause mortality. Compared with the first exposure quartile of O₃, HRs of mortality associated with the second, third, and highest exposure quartiles were 1.09 (95% CI: 0.95-1.25), 1.02 (95% CI: 0.88-1.19), and 1.56 (95% CI: 1.34-1.82), respectively. A J-shaped concentration-response association was observed, revealing a non-significant increase in risk below a concentration of approximately 110 μg m^-3. Low-temperature-exposure residents had a higher risk of mortality associated with long-term O₃ exposure. This study expands current epidemiological evidence from China and reveals that high-concentration O₃ exposure curtails the long-term survival of middle-aged and older adults.

Individual and joint associations of long-term exposure to air pollutants and cardiopulmonary mortality: a 22-year cohort study in Northern China

Background

Evidence on the associations between long-term exposure to multiple air pollutants and cardiopulmonary mortality is limited, especially for developing regions with higher pollutant levels. We aimed to characterise the individual and joint (multi-pollutant) associations of long-term exposure to air pollutants with cardiopulmonary mortality, and to identify air pollutant that primarily contributes to the mortality risk.

Methods

We followed 37,442 participants with a mean age of 43.5 years in four cities in northern China (Tianjin, Shenyang, Taiyuan, and Rizhao) from January 1998 to December 2019. Annual particulate matter (PM) with diameters ≤2.5 μm (PM2.5), ≤10 μm (PM10), sulfur dioxide (SO2) and nitrogen dioxide (NO2) were estimated using daily average values from satellite-derived machine learning models and monitoring stations. Time-varying Cox proportional hazards model was used to evaluate the individual association between air pollutants and mortality from non-accidental causes, cardiovascular diseases (CVDs), non-malignant respiratory diseases (RDs) and lung cancer, accounting for demographic and socioeconomic factors. Effect modifications by age, sex, income and education level were also examined. Quantile-based g-Computation integrated with time-to-event data was additionally applied to evaluate the co-effects and the relative weight of contributions for air pollutants.

Findings

During 785,807 person-years of follow-up, 5812 (15.5%) died from non-accidental causes, among which 2932 (7.8%) were from all CVDs, 479 (1.3%) from non-malignant RDs, and 552 (1.4%) from lung cancer. Long-term exposure to PM10 (mean [baseline]: 136.5 μg/m3), PM2.5 (mean [baseline]: 70.2 μg/m3), SO2 (mean [baseline]: 113.0 μg/m3) and NO2 (mean [baseline]: 39.2 μg/m3) were adversely and consistently associated with all mortality outcomes. A 10 μg/m3 increase in PM2.5 was associated with higher mortality from non-accidental causes (hazard ratio 1.20; 95% confidence interval 1.17-1.23), CVDs (1.23; 1.19-1.28), non-malignant RDs (1.37; 1.25-1.49) and lung cancer (1.14; 1.05-1.23). A monotonically increasing curve with linear or supra-linear shape with no evidence of a threshold was observed for the exposure-response relationship of mortality with individual or joint exposure to air pollutants. PM2.5 consistently contributed most to the elevated mortality risks related to air pollutant mixture, followed by SO2 or PM10.

Interpretation

There was a strong and positive association of long-term individual and joint exposure to PM10, PM2.5, SO2, and NO2 with mortalities from non-accidental causes, CVDs, non-malignant RDs and lung cancer in high-exposure settings, with PM2.5 potentially being the main contributor. The shapes of associations were consistent with a linear or supra-linear exposure-response relationship, with no lower threshold observed within the range of concentrations in this study.

Funding

National Key Research and Development Program of China, the China Scholarship Council, the National Natural Science Foundation of China, Natural Science Foundation of Guangdong Province.

Long-term exposure to fine particulate matter and cardiovascular disease: The mitigation role of environmental concerns

Although it is widely acknowledged that environmental concerns can reduce PM_2.5 pollution, few studies have empirically estimated whether environmental concerns could bring health benefits by mitigating PM_2.5 pollution. Here, we quantified government and media environmental concerns with text-mining algorithm, matched with cohort data along with high-resolution gridded PM_2.5 data. Accelerated failure time model and mediation model were used to explore the association between PM_2.5 exposure and onset time to cardiovascular events, and the mitigation effect of environmental concerns. Every 1 μg/m³ increase in PM_2.5 exposure was associated with shortened time to stroke and heart problem, with time ratios of 0.9900 and 0.9986, respectively. Each 1 unit increase in government and media environmental concerns, as well as their synergistic effect decreased PM_2.5 pollution by 0.32 %, 0.25 % and 0.46 %, respectively; and decrease PM_2.5 resulted in prolonged onset time to cardiovascular events. Mediation analysis revealed that reduced PM_2.5 mediated up to 33.55 % of the association between environmental concerns and onset time to cardiovascular events, suggesting that other mediation pathways were also possible. Associations of PM_2.5 exposure and environmental concerns with stroke and heart problem were similar in different subgroups. Overall, environmental concerns reduce risks of cardiovascular disease by mitigating PM_2.5 pollution and other pathways in a real-world data set. This study provides insights for low-and-middle-income countries to address air pollution and improve health co-benefit.

Ambient particulate matter, a novel factor hindering life spans of HIV/AIDS patients: Evidence from a ten-year cohort study in Hubei, China

BACKGROUND

The life spans of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) patients have been extended in the era of antiretroviral therapy. However, few studies have considered the influence of the environment on the life expectancy of people living with HIV/AIDS. Several studies have investigated mortality and air pollution associations, but the evidence for associations between long-term exposure to particulate matter (PM) and mortality among HIV/AIDS patients remains extremely sparse.

METHODS

We conceived a dynamic cohort study by enrolling people with HIV/AIDS from 103 counties in Hubei province, China from 2010 to 2019, with 23,809 persons and 78,457.2 person-years of follow-up. The county-level annual concentrations of PM_2.5 and PM₁₀ were extracted from the ChinaHighAirPollutants dataset. Cox proportional hazards models with time-varying exposures were conducted to assess the associations between PM and mortality.

RESULTS

Per 1 μg/m³ increased in PM_2.5 and PM₁₀ would elevate 0.69 % (95 % CIs: 0.39, 1.00) and 0.39 % (95 % CIs: 0.18, 0.59) risk of all-cause deaths (ACD) and 1.65 % (95 % CIs: 1.14, 2.17) and 0.90 % (95 % CIs: 0.56, 1.24) of AIDS-related deaths (ARD), respectively. Significantly stronger associations of PM-ARD were found in patients aged over 60 years old, with corresponding excess risk of 2.66 % (95 % CIs: 1.76, 3.58) for PM_2.5 and 1.62 (95 % CIs: 1.01, 2.23) for PM₁₀.

CONCLUSIONS

This study added to the existing evidence that long-term exposure to ambient PM adversely affects the life spans of HIV/AIDS patients. Hence, public health departments should take proactive measures to prevent further life loss and promote survival among those living with HIV/AIDS.

Ambient PM2.5, ozone and mortality in Chinese older adults: A nationwide cohort analysis (2005-2018)

BACKGROUND

Cohort evidence linking long-term survival with exposure to multiple air pollutants (e.g., fine particulate matter [PM_2.5] and ozone) was extensively sparse in low- and middle-income countries, especially among older adults. This study aimed to investigate potential associations of long-term exposures to PM_2.5 and ozone with all-cause mortality in Chinese older adults.

METHODS

A dynamic nationwide prospective cohort comprising 20,352 adults aged ≥65 years were enrolled from the Chinese Longitudinal Healthy Longevity Study and followed up through 2005-2018. Participants' annual exposures to warm-season ozone and year-round PM_2.5 were assigned using satellite-derived spatiotemporal estimates. A directed acyclic graph (DAG) was developed to identify confounding variables. Associations of annual mean exposures to PM_2.5 and ozone with mortality were evaluated using single- and two-pollutant Cox proportional hazards models, adjusting for time-dependent individual risk factors and ambient temperature.

RESULTS

During 100 thousand person-years of follow-up (median: 3.6 years), a total of 14,313 death events occurred. The participants were averagely aged 87.1 years at baseline and exposed to a wide range of annual average concentrations of warm-season maximum 8-hour ozone (mean, 54.4 ppb; range, 23.3-81.6 ppb) and year-round PM_2.5 (mean, 65.5 μg/m³; range, 10.1-162.9 μg/m³). Approximately linear concentration-response relationship was identified for ozone, whereas significant increases in PM_2.5-associated mortality risks were observed only when concentrations were above 60 μg/m³. Rises of 10 ppb in ozone and 10 µg/m³ in PM_2.5 above 60 µg/m³ were associated with increases in all-cause mortality of 13.2% (95% confidence interval [CI]: 10.2-16.2%) and 6.2% (95% CI: 4.6-7.7%) in DAG-based single-pollutant model, and of 9.7% (95% CI: 6.6-13.0%) and 5.3% (95% CI: 3.7-6.9%) in DAG-based two-pollutant model, respectively. We detected significant effect modification by temperature in associations of mortality with ozone (P <0.001 for interaction), suggesting greater ozone-related risks among participants in warmer locations.

CONCLUSIONS

This study provided longitudinal evidence that long-term exposure to ambient PM_2.5 and ozone significantly and independently contributed to elevated risks of all-cause mortality among older adults in China.

Long-term exposure to particulate matter on cardiovascular and respiratory diseases in low- and middle-income countries: A systematic review and meta-analysis

Background

Long-term exposure to particulate matter (PM) has essential and profound effects on human health, but most current studies focus on high-income countries. Evidence of the correlations between PM and health effects in low- and middle-income countries (LMICs), especially the risk factor PM1 (particles &lt; 1 μm in size), remains unclear.

Objective

To explore the effects of long-term exposure to particulate matter on the morbidity and mortality of cardiovascular and respiratory diseases in LMICs.

Methods

A systematic search was conducted in the PubMed, Web of Science, and Embase databases from inception to May 1, 2022. Cohort studies and case-control studies that examine the effects of PM1, PM2.5, and PM10 on the morbidity and mortality of cardiovascular and respiratory diseases in LMICs were included. Two reviewers independently selected the studies, extracted the data, and assessed the risk of bias. Outcomes were analyzed via a random effects model and are reported as the relative risk (RR) with 95% CI.

Results

Of the 1,978 studies that were identified, 38 met all the eligibility criteria. The studies indicated that long-term exposure to PM2.5, PM10, and PM1 was associated with cardiovascular and respiratory diseases: (1) Long-term exposure to PM2.5 was associated with an increased risk of cardiovascular morbidity (RR per 1.11 μg/m3, 95% CI: 1.05, 1.17) and mortality (RR per 1.10 μg/m3, 95% CI: 1.06, 1.14) and was significantly associated with respiratory mortality (RR 1.31, 95% CI: 1.25, 1.38) and morbidity (RR 1.08, 95% CI: 1.02, 1.04); (2) An increased risk of respiratory mortality was observed in the elderly (65+ years) (RR 1.21, 95% CI: 1.00, 1.47) with long-term exposure to PM2.5; (3) Long-term exposure to PM10 was associated with cardiovascular morbidity (RR 1.07, 95% CI 1.01, 1.13), respiratory morbidity (RR 1.43, 95% CI: 1.21, 1.69) and respiratory mortality (RR 1.28, 95% CI 1.10, 1.49); (4) A significant association between long-term exposure to PM1 and cardiovascular disease was also observed.

Conclusions

Long-term exposure to PM2.5, PM10 and PM1 was all related to cardiovascular and respiratory disease events. PM2.5 had a greater effect than PM10, especially on respiratory diseases, and the risk of respiratory mortality was significantly higher for LMICs than high-income countries. More studies are needed to confirm the effect of PM1 on cardiovascular and respiratory diseases.

Overview of particulate air pollution and human health in China: Evidence, challenges, and opportunities

Ambient particulate matter (PM) pollution in China continues to be a major public health challenge. With the release of the new WHO air quality guidelines in 2021, there is an urgent need for China to contemplate a revision of air quality standards (AQS). In the recent decade, there has been an increase in epidemiological studies on PM in China. A comprehensive evaluation of such epidemiological evidence among the Chinese population is central for revision of the AQS in China and in other developing countries with similar air pollution problems. We thus conducted a systematic review on the epidemiological literature of PM published in the recent decade. In summary, we identified the following: (1) short-term and long-term PM exposure increase mortality and morbidity risk without a discernible threshold, suggesting the necessity for continuous improvement in air quality; (2) the magnitude of long-term associations with mortality observed in China are comparable with those in developed countries, whereas the magnitude of short-term associations are appreciably smaller; (3) governmental clean air policies and personalized mitigation measures are potentially effective in protecting public and individual health, but need to be validated using mortality or morbidity outcomes; (4) particles of smaller size range and those originating from fossil fuel combustion appear to show larger relative health risks; and (5) molecular epidemiological studies provide evidence for the biological plausibility and mechanisms underlying the hazardous effects of PM. This updated review may serve as an epidemiological basis for China’s AQS revision and proposes several perspectives in designing future health studies.

•

Acute effects of PM are smaller in China compared with developed countries

•

Health effects caused by PM depend on particle composition, source, and size

•

There are no thresholds for the health effects of PM

•

Mechanistic studies support the biological plausibility of PM’s health effects

Blue sky as a protective factor for cardiovascular disease

Objective

Blue sky has been considered to boost outdoor physical activity and social interaction, ameliorate work pressure and life stress, and enhance people's sense of happiness. However, the direct association between blue sky exposure and cardiovascular disease (CVD) still lacks epidemiological evidence. In this study, we aimed to quantify their relationship via a nationwide prospective cohort in China.

Method

We extracted the baseline data from the China Hypertension Survey (CHS), by enrolling 22,702 participants aged ≥ 35 years without self-reported medical history of CVD from 14 provinces of China between 2012 and 2015 and followed up from 2018 to 2019. A blue day was marked out with no rain, low cloud cover ≤ climatological mean at each station, and visibility at 2 pm ≥ 21.52 km. We calculated the number of blue days at baseline survey year to evaluate the chronic individual blue day exposure. Cox proportional hazards models were employed to calculate the multivariable-adjusted hazard ratio (HR). We implemented subgroup analyses as well to identify potential effect modifications.

Results

A total of 1,096, 993, and 597 incident cases of all-cause mortality, fatal or nonfatal CVD, and stroke occurred during a median follow-up around 5 years, respectively. A 10-day increase in annual blue day exposure was associated with a 3% (95% confidence interval [CI]: 1-6%) and 7% (95% CI: 5-10%) decreased risk of fatal or nonfatal CVD and stroke, respectively. Compared with those exposed to the worst tertile of blue days at baseline, subjects who exposed to the best tertile had a 32% (95% CI: 19-43%) and 43% (95% CI: 29-55%) lower likelihood of developing fatal or nonfatal CVD and stroke, respectively. Negative consistent exposure-response relationships were generally observed between them in the restricted cubic spline model. In the stratified analyses, the cardioprotective effects of blue sky were stronger for females, rural residents, and individuals residing in heavily contaminated areas.

Conclusion

This study indicates that blue sky may serve as an independent environmental protective factor against CVD, and informs future policies on fighting air pollution and protecting the blue sky in China.

Long-term characterization of roadside air pollutants in urban Beijing and associated public health implications

Road traffic constitutes a major source of air pollutants in urban Beijing, which are responsible for substantial premature mortality. A series of policies and regulations has led to appreciable traffic emission reductions in recent decades. To shed light on long-term (2014-2020) roadside air pollution and assess the efficacy of traffic control measures and their effects on public health, this study quantitatively evaluated changes in the concentrations of six key air pollutants (PM_2.5, PM₁₀, NO₂, SO₂, CO and O₃) measured at 5 roadside and 12 urban background monitoring stations in Beijing. We found that the annual mean concentrations of these air pollutants were remarkably reduced by 47%-71% from 2014 to 2020, while the concurrent ozone concentration increased by 17.4%. In addition, we observed reductions in the roadside increments in PM_2.5, NO₂, SO₂ and CO of 54.8%, 29.8%, 20.6%, and 59.1%, respectively, indicating the high effectiveness of new vehicle standard (China V and VI) implementation in Beijing. The premature deaths due to traffic emissions were estimated to be 8379 and 1908 cases in 2014 and 2020, respectively. The impact of NO₂ from road traffic relative to PM_2.5 on premature mortality was comparable to that of traffic-related PM_2.5 emissions. The public health effect of SO₂ originating from traffic was markedly lower than that of PM_2.5. The results indicated that a reduction in traffic-related NO₂ could likely yield the greatest benefits for public health.

Mortality burden due to long-term exposure to ambient PM2.5 above the new WHO air quality guideline based on 296 cities in China

OBJECTIVE

Quantifying the spatial and socioeconomic variation of mortality burden attributable to particulate matters with aerodynamic diameter ≤ 2.5 µm (PM2.5) has important implications for pollution control policy. This study aims to examine the regional and socioeconomic disparities in the mortality burden attributable to long-term exposure to ambient PM2.5 in China.

METHODS

Using data of 296 cities across China from 2015 to 2019, we estimated all-cause mortality (people aged ≥ 16 years) attributable to the long-term exposure to ambient PM2.5 above the new WHO air quality guideline (5 µg/m3). Attributed fraction (AF), attributed deaths (AD), attributed mortality rate (AMR) and total value of statistical life lost (VSL) by regional and socioeconomic levels were reported.

RESULTS

Over the period of 2015-2019, 17.0% [95% confidence interval (CI): 7.4-25.2] of all-cause mortality were attributable to long-term exposure to ambient PM2.5, corresponding to 1,425.2 thousand deaths (95% CI: 622.4-2,099.6), 103.5/105 (95% CI: 44.9-153.3) AMR, and 1006.9 billion USD (95% CI: 439.8-1483.4) total VSL per year. The AMR decreased from 120.5/105 (95% CI: 52.9-176.6) to 92.7/105 (95% CI:39.9-138.5) from 2015 to 2019. The highest mortality burden was observed in the north region (annual average AF = 24.2%, 95% CI: 10.8-35.1; annual average AMR = 137.0/105, 95% CI: 60.9-198.5). The highest AD and economic loss were observed in the east region (annual average AD = 390.0 thousand persons, 95% CI: 170.3-574.6; annual total VSL = 275.6 billion USD, 95% CI: 120.3-406.0). Highest AMR was in the cities with middle level of GDP per capita (PGDP)/urbanization. The majority of the top ten cities of AF, AMR and VSL were in high and middle PGDP/urbanization regions.

CONCLUSION

There were significant regional and socioeconomic disparities in PM2.5 attributed mortality burden among Chinese cities, suggesting differential mitigation policies are required for different regions in China.

Interactive effects of cold spell and air pollution on outpatient visits for anxiety in three subtropical Chinese cities

BACKGROUND

Although low temperature and air pollution exposures have been associated with the risk of anxiety, their combined effects remain unclear.

OBJECTIVE

To investigate the independent and interactive effects of low temperature and air pollution exposures on anxiety.

METHOD

Using a case-crossover study design, the authors collected data from 101,636 outpatient visits due to anxiety in three subtropical Chinese cities during the cold season (November to April in 2013 through 2018), and then built conditional logistic regression models based on individual exposure assessments [temperature, relative humidity, particulate matter (PM_2.5, PM₁₀), sulfur dioxide (SO₂), and nitrogen dioxide (NO₂)] and twelve cold spell definitions. Additive-scale interactions were assessed using the relative excess risk due to interaction (RERI).

RESULTS

Both cold spell and air pollution were significantly associated with outpatients for anxiety. The effects of cold spell increased with its intensity, ranging from 8.98% (95% CI: 2.02%, 16.41%) to 15.24% (95% CI: 6.75%, 24.39%) in Huizhou. Additionally, each 10 μg/m³ increase of PM_2.5, PM₁₀, NO₂ and SO₂ was associated with a 1.51% (95% CI: 0.61%, 2.43%), 1.58% (95% CI: 0.89%, 2.28%), 13.95% (9.98%, 18.05%) and 11.84% (95% CI: 8.25%, 15.55%) increase in outpatient visits for anxiety. Synergistic interactions (RERI >0) of cold spell with all four air pollutants on anxiety were observed, especially for more intense cold spells. For particulate matters, these interactions were found even under mild cold spell definitions [RERI: 0.11 (95% CI: 0.02, 0.21) for PM_2.5, and 0.24 (95% CI: 0.14, 0.33) for PM₁₀]. Stratified analyses yielded a pronounced results in people aged 18-65 years.

CONCLUSIONS

These findings indicate that both cold spell and air pollution are important drivers of the occurrence of anxiety, and simultaneous exposure to these two factors might have synergistic effects on anxiety. These findings highlight the importance of controlling air pollution and improving cold-warning systems.

Health Effects of Long-Term Exposure to Ambient PM2.5 in Asia-Pacific: a Systematic Review of Cohort Studies

Abstract

Purpose of Review

Health effects of long-term exposure to ambient PM_2.5 vary with regions, and 75% of the deaths attributable to PM_2.5 were estimated in Asia-Pacific in 2017. This systematic review aims to summarize the existing evidence from cohort studies on health effects of long-term exposure to ambient PM_2.5 in Asia-Pacific.

Recent Findings

In Asia-Pacific, 60 cohort studies were conducted in Australia, Mainland China, Hong Kong, Taiwan, and South Korea. They consistently supported associations of long-term exposure to PM_2.5 with increased all-cause/non-accidental and cardiovascular mortality as well as with incidence of cardiovascular diseases, type 2 diabetes mellitus, kidney diseases, and chronic obstructive pulmonary disease. Evidence for other health effects was limited. Inequalities were identified in PM_2.5-health associations.

Summary

To optimize air pollution control and public health prevention, further studies need to assess the health effects of long-term PM_2.5 exposure in understudied regions, the health effects of long-term PM_2.5 exposure on mortality and risk of type 2 diabetes mellitus, renal diseases, dementia and lung cancer, and inequalities in PM_2.5-health associations. Study design, especially exposure assessment methods, should be improved.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40572-022-00344-w.

Spatial Distribution of PM2.5-Related Premature Mortality in China

PM2.5 is a major component of air pollution in China and has a serious threat to public health. It is very important to quantify spatial characteristics of the health effects caused by outdoor PM2.5 exposure. This study analyzed the spatial distribution of PM2.5 concentration (45.9 μg/m3 national average in 2016) and premature mortality attributed to PM2.5 in cities at the prefectural level and above in China in 2016. Using the Global Exposure Mortality Model (GEMM), the total premature mortality in China was estimated to be 1.55 million persons, and the per capita mortality was 11.2 per 10,000 persons in the year 2016, resulting in higher estimates compared to the integrated exposure-response model. We assessed the premature mortality attributed to PM2.5 through common diseases, including ischemic heart disease (IHD), cerebrovascular disease (CEV), chronic obstructive pulmonary disease (COPD), lung cancer (LC), and lower respiratory infections (LRI). The premature mortality due to IHD and CEV accounted for 68.5% of the total mortality, and the per capita mortality (per 10,000 persons) for all ages due to IHD was 3.86, the highest among diseases. For the spatial distribution of disease-specific premature mortality, the top two highest absolute numbers of premature mortality associated with IHD, CEV, LC, and LRI, respectively, were found in Chongqing and Beijing. In 338 cities of China, we have found a significant positive spatial autocorrelation of per capita premature mortality, indicating the necessity of coordinated regional governance for an efficient control of PM2.5.

Declines in heart rate variability associated with short-term PM2.5 exposure were modified by blood pressure control and treatment: A multi-city panel study in China

Exposure to fine particulate matter (PM_2.5) was associated with altered heart rate variability (HRV). However, whether blood pressure (BP) control and angiotensin II receptor blocker (ARB) treatment modifies the associations was seldom addressed. Therefore, we conducted a 3-phase panel study among 282 hypertensive subjects aged 35-74 years in four cities of China to address this issue. Real-time personal PM_2.5 sampling and 24-h ambulatory electrocardiogram monitoring were performed repeatedly in 3 different seasons. Linear mixed-effects models were fitted overall and by control status of BP and ARB treatment to assess the associations between short-term PM_2.5 exposure and HRV. The average hourly PM_2.5 concentrations (Mean ± SD) ranged from 19.3 ± 18.2 μg/m³ to 99.4 ± 76.9 μg/m³ across study phases and cities. Generally, PM_2.5 exposure was associated with decreased hourly and 24-h HRV. However, these adverse impacts were attenuated among patients with controlled BP (<140/90 mmHg). For each 10 μg/m³ increment in moving average of previous 2 days' (MA2d) PM_2.5 exposure, 24-h SDNN (standard deviation of NN intervals) and rMSSD (root mean square of successive RR interval differences) decreased by 0.89% (95% CI: 0.19%-1.59%) and 2.98% (95% CI: 1.04%-4.89%) among patients with uncontrolled BP (≥140/90 mmHg), whereas no obvious declines were observed among those with controlled BP (P_difference = 0.007 and 0.022, respectively). Furthermore, ARB treatment alleviated or eliminated PM_2.5-associated declines in hourly and 24-h HRV among those with uncontrolled BP. For instance, 24-h SDNN decreased by 1.31% (95% CI: 0.54%-2.07%) with a 10 μg/m³ increment in lag 2 days' PM_2.5 exposure in ARB nonusers, whereas no obvious changes were observed in ARB users (P_difference = 0.021). In conclusion, although PM_2.5 exposure would decrease HRV, better BP control and ARB treatment could attenuate these adverse impacts, which provides supporting evidence for alleviating autonomic dysfunction of hypertension patients living in areas with high-level PM_2.5.

The prospective effects of long-term exposure to ambient PM2.5 and constituents on mortality in rural East China

Few cohort studies explored the associations of long-term exposure to ambient fine particulate matter with an aerodynamic diameter of 2.5 μm or less (PM2.5) and its chemical constituents with mortality risk in rural China. We conducted a 12-year prospective study of 28,793 adults in rural Deqing, China from 2006 to 2018. Annual mean PM2.5 and its constituents, including black carbon (BC), organic carbon (OC), ammonium (NH4+), nitrate (NO3-), sulfate (SO42-), and soil dust were measured at participants' addresses at enrollment from a satellite-based exposure predicting model. Cox proportional hazard model was used to estimate hazard ratios (HRs) and 95% confidence intervals (95%CIs) of long-term exposure to PM2.5 for mortality. A total of 1960 deaths were identified during the follow-up. We found PM2.5, BC, OC, NH4+, NO3-, and SO42- were significantly associated with an increased risk of non-accidental mortality. The HR for non-accidental mortality was 1.17 (95%CI: 1.07, 1.28) for each 10 μg/m3 increase in PM2.5. As for constituents, the strongest association was found for BC (HR = 1.21, 95%CI: 1.11, 1.33), followed by NO3-, NH4+, SO42-, and OC (HR = 1.14-1.17 per interquartile range). A non-linear relationship was found between PM2.5 and non-accidental mortality. Similar associations were found for cardio-cerebrovascular and cancer mortality. Associations were stronger among men and ever smokers. Conclusively, we found long-term exposure to ambient PM2.5 and its chemical constituents (especially BC and NO3-) increased mortality risk. Our results suggested the importance of adopting effective targeted emission control to improve air quality for health protection in rural East China.

Observations on the particle pollution of the cities in China in the Coronavirus 2019 closure: Characteristics and lessons for environmental management

Particulate matter in the air seriously affects human health and has been a hot topic of discussion. Because of the coronavirus disease 2019 (COVID-19) lockdown in cities in China, sources of particulate matter, including gasoline-burning vehicles, dust-producing building sites, and coal-fired factories, almost all ceased at the end of January 2020. It was not until early April that outdoor activities recovered. Ten cities were selected as observation sites during the period from 19 December 2019 to 30 April 2020, covering the periods of preclosure, closure, and gradual resumption. A total of 11 720 groups of data were obtained, and 4 indicators were used to assess the characteristics of the particle pollution in the period. The quality of the atmospheric environment was visibly influenced by human activities in those 5 mo. The concentrations of particulate matter with particle sizes below 10 µm (PM10) decreased slightly in February and March and then began to increase slowly after April with the gradual recovery of production. The concentrations of particulate matter with particle sizes below 2.5 µm (PM2.5) decreased greatly in most regions, especially in northern cities, during closure and maintained a relatively stable level in the following 3 mo. The trends of PM10 and PM2.5 indicated that the reduced human activities during the COVID-19 lockdown decreased the concentrations of particulate matter in the air, and the difference between the PM10 and PM2.5 trends might be due to the different sources of the 2 particles and their different aerodynamics. However, during closure, the particulate matter pollution in the cities remained at a high level, which indicated that some ignored factors other than outdoor production activities, automobile exhaust, and construction site dust might have contributed greatly to the PM10 and PM2.5 concentrations, and the tracing of the particulate matter should be given further attention in environmental management. Integr Environ Assess Manag 2021;17:1014-1024. © 2021 SETAC.

Benefits of active commuting on cardiovascular health modified by ambient fine particulate matter in China: A prospective cohort study

BACKGROUND

Active commuting as a contributor to daily physical activity is beneficial for cardiovascular health, but leads to more chances of exposure to ambient air pollution. This study aimed to investigate associations between active commuting to work with cardiovascular disease (CVD), mortality and life expectancy among general Chinese adults, and to further evaluate the modification effect of fine particulate matter (PM2.5) exposure on these associations.

METHODS

We included 76,176 Chinese adults without CVD from three large cohorts of the Prediction for Atherosclerotic Cardiovascular Disease Risk in China project. Information about commuting mode and physical activity were collected by unified questionnaire. Satellite-based PM2.5 concentrations at 1-km spatial resolution was used for estimating PM2.5 exposure of participants. Hazard ratios (HRs) and 95% confidence intervals (CIs) for CVD incidence, mortality and all-cause mortality were estimated using Cox proportional hazards regression models. Multiplicative interaction term of commuting mode and PM2.5 level was tested to investigate potential effect modification.

RESULTS

During 448,499 person-years of follow-up, 2230 CVD events and 2777 all-cause deaths were recorded. Compared with the non-active commuters, the multivariable-adjusted HRs (95% CIs) of CVD incidence and all-cause mortality were 0.95(0.85-1.05) and 0.79(0.72-0.87) for walking commuters, respectively. Corresponding HRs (95% CIs) for cycling commuters were 0.71(0.62-0.82) and 0.67(0.59-0.76). Active commuters over 45 years old were estimated to have more CVD-free years and life expectancy than non-active commuters under lower PM2.5 concentration. However, these beneficial effects of active commuting were alleviated or counteracted by long-term exposure to high PM2.5 concentration. Significant multiplicative interaction of commuting mode and PM2.5 level was showed in all-cause mortality, with the lowest risk observed in cycling participants exposed to lower level of PM2.5.

CONCLUSIONS

Active commuting was associated with lower risk of CVD, all-cause mortality, and longer life expectancy among Chinese adults under ambient settings with lower PM2.5 level. It will be valuable to encourage active commuting among adults and develop stringent strategies on ambient PM2.5 pollution control for prevention of CVD and prolongation of life expectancy.

Air Pollution Observations in Selected Locations in Poland during the Lockdown Related to COVID-19

The coronavirus disease (COVID-19) has caused huge changes in people’s daily habits and had a significant impact on the economy. The lockdowns significantly reduced road traffic and meant that many people worked remotely. Therefore, the question arose as to how the reduced road traffic and stays of residents at home affected the degree of pollution and the structure of major air pollutants. To answer this question, the article presents an analysis of changes in typical air pollutants (PM10, PM2.5, NO2) in the five largest Polish cities and one of the voivodships. The data from the Polish State Environmental Monitoring were used for the analysis. The analysis showed that the period of the first lockdown in Poland (April 2020), despite the reduced road traffic, resulted in a significant increase in PM10 emissions (9–91% during working days and an average of 30% on Saturdays and Sundays), a slight increase in PM2.5 emissions (on average from 2% to 11% for all analyzed locations), and a reduction in NO2 emissions (on average from 6% to 11% for all analyzed locations) compared to the period before the lockdown. However, the changes were not homogeneous—in Łódź and Warsaw, in most cases, an increase in all analyzed pollutants was observed, and the greatest decrease in pollution took place in Małopolska voivodship (including Kraków). Comparing the data from April 2020 to the data from April 2019, the overall difference in the PMs concentrations was small, although there are places where there has been a significant decrease (Wrocław, Poznań), and there were also places where the concentration increased (Warsaw, Łódź, Małopolska). In the case of nitrogen dioxide, pollution concentration decreased in most locations. The only exception was the background stations in Warsaw, where the increase was 27%.

Long-term temperature variability and the incidence of cardiovascular diseases: A large, representative cohort study in China

In the context of global climate change, far less is known about the impact of long-term temperature variability (TV), especially in developing countries. The current study aimed to estimate the effect of long-term TV on the incidence of cardiovascular disease (CVD) in China. A total of 23,721 individuals with a mean age of 56.15 years were enrolled at baseline from 2012 to 2016 and followed up during 2017-2019. TV was defined as the standard deviation of daily temperatures during survey years and was categorized into tertiles (lowest≤ 8.78 °C, middle = 8.78-10.07 °C, highest ≥ 10.07 °C). The Cox proportional hazards regression was used to estimate the multivariable-adjusted hazard ratio (HR) between TV and CVD. During the median follow-up of 4.65 years, we ascertained 836 cases of incident CVD. For per 1 °C increase in TV, there was a 6% increase of CVD (HR = 1.06 [95% confidence interval (CI): 1.01-1.11]). A significant positive trend was observed between CVD risk and increasing levels of TV compared to the lowest tertile [HR = 1.34 (95% CI: 1.13-1.59) for the medium tertile, HR = 1.72 (95% CI: 1.35-2.19) for the highest tertile, P_trend < 0.001]. Exposure to high TV would lose 2.11 disease-free years for the population aged 35-65 years and 66 CVD cases (or 7.95% cases) could been attributable to TV higher than 8.11 °C in the current study. The current findings suggested that long-term TV was associated with a higher risk of CVD incidence, it is needed to reduce the TV-related adverse health effect.

All-Cause Mortality Risk and Attributable Deaths Associated with Long-Term Exposure to Ambient PM2.5 in Chinese Adults

Several recent studies in China have associated raised mortality risks with chronic exposure to ambient PM_2.5. However, cohort evidence covering general populations and more homogeneous regions is extensively scarce. We conceived a nationwide perspective cohort study from 2010 through 2018, by enrolling 30 946 adult men and women aged 16-110 years from 25 provincial regions in mainland China. Cox proportional hazards models with time-varying exposures were adopted to quantify longitudinal association of PM_2.5 exposure with all-cause mortality. A total of 1762 death events occurred during a median follow-up of 8.1 years. Participants were exposed to a broad range of annual mean PM_2.5 concentrations (2.4-112 μg/m³), with an average estimate of 47.5 μg/m³. A 10-μg/m³ increase in annual average of PM_2.5 exposure was associated with an hazard ratio of 1.055 (95% confidence interval: 1.022-1.088, p < 0.001) for all-cause mortality. We estimated totally 2.68 million deaths attributable to ambient PM_2.5 in 2015, yielding a remarkable reduction of 36.7 thousand compared to the estimate in 2010 (2.72 million deaths). This study added nationally representative evidence regarding concentration-response function for long-term PM_2.5-mortality association in Chinese adults, which may significantly contribute to national and global assessments of PM_2.5-attributable death burden.

Long-term exposure to fine particulate matter relates with incident myocardial infarction (MI) risks and post-MI mortality: A meta-analysis

BACKGROUND

Air pollution has become a global challenge, and a growing number of studies have suggested possible relationships between long-term exposure to fine particulate matter (PM_2.5) and risks of cardiovascular events, specifically, myocardial infarction (MI). However, the recently reported results were inconsistent. We thus performed a meta-analysis and sought to assess whether long-term exposure to PM_2.5 relates with incident MI risks and post-MI mortality.

METHODS

EMBASE, Web of Science and PubMed were searched for all potentially eligible studies published before August 2, 2020 using a combination of keywords related to PM_2.5 exposure, its long-term effects and myocardial infarction. Key information was extracted, and calculated hazard ratio (HR) values were combined by selecting corresponding models according to heterogeneity test. A sensitivity analysis and a publication bias assessment were also performed to determine the reliability of the results.

RESULTS

Of the initially identified 2100 citations, 12 studies met our inclusion criteria and observed a total population of approximately 7.2 million. Pooled estimates (per 10 μg/m³ increase) indicated a statistically significant association between long-term PM_2.5 exposure and MI incidence (HR = 1.10, 95% CI: 1.02-1.18) or post-MI mortality (HR = 1.07, 95% CI: 1.04-1.09). Results for MI incidence from Egger's linear regression method (P = 0.515) and Begg's test (P = 0.711) showed no obvious publication bias.

CONCLUSION

Our quantitative analysis reveals a significant link between long-term PM_2.5 exposure and greater MI incidence risks or higher post-MI mortality. Our findings may therefore have implications for individual protection and policy support to improve public health.

High-Resolution Spatiotemporal Modeling for Ambient PM2.5 Exposure Assessment in China from 2013 to 2019

Exposure to fine particulate matter (PM_2.5) has become a major global health concern. Although modeling exposure to PM_2.5 has been examined in China, accurate long-term assessment of PM_2.5 exposure with high spatiotemporal resolution at the national scale is still challenging. We aimed to establish a hybrid spatiotemporal modeling framework for PM_2.5 in China that incorporated extensive predictor variables (satellite, chemical transport model, geographic, and meteorological data) and advanced machine learning methods to support long-term and short-term health studies. The modeling framework included three stages: (1) filling satellite aerosol optical depth (AOD) missing values; (2) modeling 1 km × 1 km daily PM_2.5 concentrations at a national scale using extensive covariates; and (3) downscaling daily PM_2.5 predictions to 100-m resolution at a city scale. We achieved good model performances with spatial cross-validation (CV) R² of 0.92 and temporal CV R² of 0.85 at the air quality sites across the country. We then estimated daily PM_2.5 concentrations in China from 2013 to 2019 at 1 km × 1 km grid cells. The downscaled predictions at 100 m resolution greatly improved the spatial variation of PM_2.5 concentrations at the city scale. The framework and data set generated in this study could be useful to PM_2.5 exposure assessment and epidemiological studies.

Premature mortality attributable to PM2.5 pollution in China during 2008-2016: Underlying causes and responses to emission reductions

Long-term exposure to fine particulate matter (PM_2.5) poses a great threat to public health in China. To this end, the Chinese government promulgated the Air Pollution Prevention and Control Action Plan (the Action Plan) in 2013. However, the health benefits of the Action Plan have not been well explained. In this paper, the underlying causes of changes in premature mortality attributable to PM_2.5 pollution and the response of this mitigation policy in China were explored using sensitivity analysis. The simulated annual average PM_2.5 concentration reduced by 24.9% over mainland China from 2008 to 2016. Subsequently, national premature mortality would decrease by 14.4% from 1.14 million (95% CI: 0.54, 1.55) in 2008 to 0.98 million (95% CI: 0.44, 1.38) in 2016. Specifically, premature mortality reduced by 209,600 cases (-18.3%) owing to PM_2.5 reduction during 2008-2016, of which 188,500 cases were from 2014 to 2016 due to the Action Plan in 2013. Note that the health benefits were limited when compared with air quality improvements, mainly due to that the IER functions have a stable curve at higher concentration intervals. Meanwhile, premature mortality would have increased by 14.2% from 2008 to 2016 owing to demographic changes, substantially weakening the impact of the decrease in PM_2.5 and baseline mortality. The effectiveness of China's new air pollution mitigation policy was proved through the research. However, considering the non-linear response of mortality to PM_2.5 changes and the aggravation of demography trends, stronger emission control steps should be further taken to protect public health in China.

Socioeconomic disparity in the association between long-term exposure to PM2.5 and mortality in 2640 Chinese counties

BACKGROUND

Although the association between long-term exposure to PM_2.5 and mortality has been evaluated intensively, little is known about the socioeconomic disparity in the association.

METHODS

We collected data on annual all-cause mortality, PM_2.5 concentration, socioeconomic and demographic characteristics of 2640 counties from the two most recent Chinese censuses in 2000 and 2010. We applied the difference-in-differences (DID) method to estimate PM_2.5-mortality association for counties at different quartiles of literacy rate, college rate, urbanization rate and GDP per capita, respectively.

RESULTS

Overall, every 10 µg/m³ increase in annual average PM_2.5 was associated with 3.8% (95% confidence interval [CI]: 3.0-5.0) increase of all-cause mortality. The stratified analysis suggested higher health impact of exposure in counties with lower socioeconomic status. For counties of the lowest quartile (Q₁) of literacy rate, college rate, urbanization rate and GDP per capita, the effect estimates were 6.0% (95% CI: 4.2-7.7), 4.4% (95% CI: 2.8-6.0), 3.5% (95% CI: 2.0-5.1) and 4.9% (95% CI: 2.7-7.1), respectively. There was strong evidence for elevated risk in mortality associated with PM_2.5 of all socioeconomic factors in the lowest quartile (Q₁) compared with the highest quartile counties (Q₄) (p-value for difference < 0.05).

CONCLUSIONS

There was socioeconomic disparity in the PM_2.5-mortality association in China. Dwellers living in less developed counties are more vulnerable to long-term exposure to ambient PM_2.5 than those living in developed counties.

The long-term trend of PM2.5-related mortality in China: The effects of source data selection

Quantification of PM_2.5 exposure and associated mortality is critical to inform policy making. Previous studies estimated varying PM_2.5-related mortality in China due to the usage of different source data, but rarely justify the data selection. To quantify the sensitivity of mortality assessment to source data, we first constructed state-of-the-art PM_2.5 predictions during 2000-2018 at a 1-km resolution with an ensemble machine learning model that filled missing data explicitly. We also calibrated and fused various gridded population data with a geostatistical method. Then we assessed the PM_2.5-related mortality with various PM_2.5 predictions, population distributions, exposure-response functions, and baseline mortalities. We found that in addition to the well documented uncertainties in the exposure-response functions, missingness in PM_2.5 prediction, PM_2.5 prediction error, and prediction error in population distribution resulted to a 40.5%, 25.2% and 15.9% lower mortality assessment compared to the mortality assessed with the best-performed source data, respectively. With the best-performed source data, we estimated a total of approximately 25 million PM_2.5-related mortality during 2001-2017 in China. From 2001 to 2017, The PM_2.5 variations, growth and aging of population, decrease in baseline mortality led to a 7.8% increase, a 42.0% increase and a 24.6% decrease in PM_2.5-related mortality, separately. We showed that with the strict clean air policies implemented in 2013, the population-weighted PM_2.5 concentration decreased remarkably at an annual rate of 4.5 μg/m³, leading to a decrease of 179 thousand PM_2.5-related deaths nationwide during 2013-2017. The mortality decrease due to PM_2.5 reduction was offset by the population growth and aging population.

The 17-y spatiotemporal trend of PM2.5 and its mortality burden in China

Investigations on the chronic health effects of fine particulate matter (PM_2.5) exposure in China are limited due to the lack of long-term exposure data. Using satellite-driven models to generate spatiotemporally resolved PM_2.5 levels, we aimed to estimate high-resolution, long-term PM_2.5 and associated mortality burden in China. The multiangle implementation of atmospheric correction (MAIAC) aerosol optical depth (AOD) at 1-km resolution was employed as a primary predictor to estimate PM_2.5 concentrations. Imputation techniques were adopted to fill in the missing AOD retrievals and provide accurate long-term AOD aggregations. Monthly PM_2.5 concentrations in China from 2000 to 2016 were estimated using machine-learning approaches and used to analyze spatiotemporal trends of adult mortality attributable to PM_2.5 exposure. Mean coverage of AOD increased from 56 to 100% over the 17-y period, with the accuracy of long-term averages enhanced after gap filling. Machine-learning models performed well with a random cross-validation R ² of 0.93 at the monthly level. For the time period outside the model training window, prediction R ² values were estimated to be 0.67 and 0.80 at the monthly and annual levels. Across the adult population in China, long-term PM_2.5 exposures accounted for a total number of 30.8 (95% confidence interval [CI]: 28.6, 33.2) million premature deaths over the 17-y period, with an annual burden ranging from 1.5 (95% CI: 1.3, 1.6) to 2.2 (95% CI: 2.1, 2.4) million. Our satellite-based techniques provide reliable long-term PM_2.5 estimates at a high spatial resolution, enhancing the assessment of adverse health effects and disease burden in China.