A county-level estimate of PM2.5 related chronic mortality risk in China based on multi-model exposure data

Exposure to urban particulate matter and its association with human health risks

Human health and environmental risks are increasing following air pollution associated with vehicular and industrial emissions in which particulate matter is a constituent. The purpose of this review was to assess studies on the health effects and mortality induced by particles published for the last 15 years. The literature survey indicated the existence of strong positive associations between fine and ultrafine particles' exposure and cardiovascular, hypertension, obesity and type 2 diabetes mellitus, cancer health risks, and mortality. Its exposure is also associated with increased odds of hypertensive and diabetes disorders of pregnancy and premature deaths. The ever increasing hospital admission and mortality due to heart failure, diabetes, hypertension, and cancer could be due to long-term exposure to particles in different countries. Therefore, its effect should be communicated for legal and scientific actions to minimize emissions mainly from traffic sources.

Geographic variations in the blood pressure responses to short-term fine particulate matter exposure in China

Results from recent studies on associations between blood pressure (BP) and short-term exposure to fine particulate matter (PM_2.5) have been inconsistent. Most studies have been evaluations of small geographic areas, with no national study in China. This study aimed to examine the acute BP responses to ambient PM_2.5 among the general population of Chinese adults. During 2012-2015, systolic and diastolic BP levels were obtained from a large national representative sample, the China Hypertension Survey database (n = 479,842). Daily PM_2.5 average exposures with a spatial resolution of 0.1° were estimated using a data assimilation that combines satellite measurements, air model simulations, and monitoring values. Overall, a 10-μg/m³ increase in daily PM_2.5 was associated with a 0.035 (95% confidence interval: 0.020, 0.049) mmHg change in systolic BP and 0.001 (-0.008, 0.011) mmHg in diastolic BP after adjustments. Stratified by geographic regions, the systolic and diastolic BP levels varied from -0.050 (-0.109, 0.010) to 0.242 (0.176, 0.307) mmHg, and from -0.026 (-0.053, 0.001) to 0.051 (0.020, 0.082) mmHg, respectively. Statistically significant positive BP-PM_2.5 associations were only found in South and North China for systolic levels and in Southwest China for diastolic levels. We further explored the regional study population characteristics and exposure-response curves, and found that the geographic variations in BP-PM_2.5 associations were probably due to different population compositions or different PM_2.5 exposure levels. Our study provided national-level evidence on the associations between ambient PM_2.5 exposure and elevated BP levels. The magnitude of the estimated associations varied substantially by geographic location in China. CLINICAL TRIAL REGISTRATION: The Clinical trial registration name was Survey on prevalence of hypertension in China; the registration number was ChiCTR-ECS-14004641. http://www.chictr.org.cn/showproj.aspx?proj=4932.

Temporal trend of arsenic in outdoor air PM2.5 in Wuhan, China, in 2015-2017 and the personal inhalation of PM-bound arsenic: implications for human exposure

Arsenic in fine air particulate matter (PM_2.5) has been identified as an important factor responsible for the morbidity of lung cancer, which has increased sharply in many regions of China. Some reports in China have shown that arsenic in the air exceeds the ambient air quality standard value, while long-term airborne arsenic concentrations in central China and human exposure via inhalation of PM-bound arsenic (inhalable airborne PM) have not been well characterized. In this study, 579 outdoor air PM_2.5 samples from Wuhan, a typical city in central China, were collected from 2015 to 2017, and arsenic was measured by inductively coupled plasma-mass spectrometry. Personal exposure to PM-bound arsenic via inhalation and urinary arsenic concentration were also measured. The concentrations of arsenic in PM_2.5 were in the range of 0.42-61.6 ng/m³ (mean 8.48 ng/m³). The average concentration of arsenic in 2015 (10.7 ng/m³) was higher than that in 2016 (6.81 ng/m³) and 2017 (8.18 ng/m³), exceeded the standard value. The arsenic concentrations in spring and winter were higher than those in summer and autumn. No significant differences (p > 0.05) were found among different sites. The daily intake of arsenic inhalation based on PM₁₀ samples collected by personal samplers (median, 10.8 ng/m³) was estimated. Urban residents inhaled higher levels of PM-bound arsenic than rural residents. Daily intake of arsenic via inhalation accounted for a negligible part (< 1%) of the total daily intake of arsenic (calculated based on excreted urinary arsenic); however, potential associations between the adverse effects (e.g., lung adenocarcinoma) and inhaled PM-bound arsenic require more attention, particularly for those who experience in long-term exposure. This study is the first report of a 3-year temporal trend of airborne PM_2.5-bound arsenic in central China.

Ambient PM2.5 and Annual Lung Cancer Incidence: A Nationwide Study in 295 Chinese Counties

Most studies have examined PM2.5 effects on lung cancer mortalities, while few nationwide studies have been conducted in developing countries to estimate the effects of PM2.5 on lung cancer incidences. To fill this gap, this work aims to examine the effects of PM2.5 exposure on annual incidence rates of lung cancer for males and females in China. We performed a nationwide analysis in 295 counties (districts) from 2006 to 2014. Two regression models were employed to analyse data controlling for time, location and socioeconomic characteristics. We also examined whether the estimates of PM2.5 effects are sensitive to the adjustment of health and behaviour covariates, and the issue of the changing cancer registries each year. We further investigated the modification effects of region, temperature and precipitation. Generally, we found significantly positive associations between PM2.5 and incidence rates of lung cancer for males and females. If concurrent PM2.5 changes by 10 g/m³, then the incidence rate relative to its baseline significantly changes by 4.20% (95% CI: 2.73%, 5.88%) and 2.48% (95% CI: 1.24%, 4.14%) for males and females, respectively. The effects of exposure to PM2.5 were still significant when further controlling for health and behaviour factors or using 5 year consecutive data from 91 counties. We found the evidence of long-term lag effects of PM2.5. We also found that temperature appeared to positively modify the effects of PM2.5 on the incidence rates of lung cancer for males. In conclusion, there were significantly adverse effects of PM2.5 on the incidence rates of lung cancer for both males and females in China. The estimated effect sizes might be considerably lower than those reported in developed countries. There were long-term lag effects of PM2.5 on lung cancer incidence in China.

Impact of Urbanization on PM2.5-Related Health and Economic Loss in China 338 Cities

According to the requirements of the Healthy China Program, reasonable assessment of residents' health risks and economic loss caused by urban air pollution is of great significance for environmental health policy planning. Based on the data of PM2.5 concentration, population density, and urbanization level of 338 Chinese cities in the year of 2015, the epidemiological relative risk (RR) was adopted to estimate the negative health effects caused by exposure to PM2.5. Meanwhile, the Value of Statistical Life (VSL) and Cost of Illness (COI) methods were used to calculate economic loss. The results show that PM2.5 pollution remains serious in 2015, which brings about many people suffering from all kinds of fearful health problems especially premature death and related diseases. The mortality and morbidity increase dramatically, and the total direct economic loss related to PM2.5 pollution in 2015 was 1.846 trillion yuan, accounting for 2.73% of total annual GDP. In addition, there was a strong correlation between urbanization level and health risks as well as economic loss, which implies that people who live in highly urbanized cities may face more severe health and economic losses. Furthermore, 338 cities were divided into four categories based on urbanization level and economic loss, of which the key areas (type D) were the regions where an increase in monitoring and governance is most needed. In the process of urbanization, policy makers should pay more attention to health costs and regional differentiated management, as well as promote the construction of healthy cities more widely.

PM2.5-Related Health Economic Benefits Evaluation Based on Air Improvement Action Plan in Wuhan City, Middle China

On the basis of PM_2.5 data of the national air quality monitoring sites, local population data, and baseline all-cause mortality rate, PM_2.5-related health economic benefits of the Air Improvement Action Plan implemented in Wuhan in 2013–2017 were investigated using health-impact and valuation functions. Annual avoided premature deaths driven by the average concentration of PM_2.5 decrease were evaluated, and the economic benefits were computed by using the value of statistical life (VSL) method. Results showed that the number of avoided premature deaths in Wuhan are 21,384 (95% confidence interval (CI): 15,004 to 27,255) during 2013–2017, due to the implementation of the Air Improvement Action Plan. According to the VSL method, the obtained economic benefits of Huangpi, Wuchang, Hongshan, Xinzhou, Jiang’an, Hanyang, Jiangxia, Qiaokou, Jianghan, Qingshan, Caidian, Dongxihu, and Hannan District were 8.55, 8.19, 8.04, 7.39, 5.78, 4.84, 4.37, 4.04, 3.90, 3.30, 2.87, 2.42, and 0.66 billion RMB (1 RMB = 0.1417 USD On 14 October 2019), respectively. These economic benefits added up to 64.35 billion RMB (95% CI: 45.15 to 82.02 billion RMB), accounting for 4.80% (95% CI: 3.37% to 6.12%) of the total GDP of Wuhan in 2017. Therefore, in the process of formulating a regional air quality improvement scheme, apart from establishing hierarchical emission-reduction standards and policies, policy makers should give integrated consideration to the relationship between regional economic development, environmental protection and residents’ health benefits. Furthermore, for improving air quality, air quality compensation mechanisms can be established on the basis of the status quo and trends of air quality, population distribution, and economic development factors.

Long-Term Exposure to Air Pollution and Survival After Ischemic Stroke

Background and Purpose- China bears a heavy burden of stroke because of its large population of elderly people and the propensity for stroke. Previous studies have examined the association between air pollution and stroke mortality or hospital admission. However, the global evidence for adverse effects of air pollution on survival after stroke is scarce. Methods- We used the first national hospital-based prospective registry cohort of stroke in China, which included 12 291 ischemic stroke patients who visited hospitals during 2007 to 2008. All patients were followed for 1-year poststroke. Deaths during the follow-up period were recorded. Participants' 3-year prestroke exposures to ambient PM₁, PM_2.5, PM₁₀ (particulate matter with aerodynamic diameters ≤1, ≤2.5, and ≤10 μm, respectively) and NO₂ (nitrogen dioxide) were estimated by machine learning algorithms with satellite remote sensing, land use information, and meteorological data. Cox proportional hazards models were used to examine the association between air pollution and survival after ischemic stroke. Results- In total, 1649 deaths were identified during the 1-year follow-up period. After controlling for potential confounders, significant associations were observed between exposure to PM₁ and PM_2.5 and incident fatal ischemic stroke. The corresponding hazard ratios and 95% CIs associated with 10 µg/m³ increase in PM₁ and PM_2.5 were 1.05 (1.02-1.09) and 1.03 (1.00-1.06), respectively. No significant association was observed for PM₁₀ or NO₂ (hazard ratios and 95% CIs, 1.01 [1.00-1.03] and 1.03 [0.99-1.06], respectively). Higher hazard ratios (and 95% CIs) were observed for male, elderly and obese individuals. Conclusions- Prestroke exposure to PM₁ and PM_2.5 was associated with increased incident fatal ischemic stroke in the year following an ischemic stroke in China. Improved air quality may be beneficial for people to recover from stroke.

Air pollution and lung cancer incidence in China: Who are faced with a greater effect?

BACKGROUND

Whether socioeconomic indicators modify the relationship between air pollution exposure and health outcomes remains uncertain, especially in developing countries.

OBJECTIVE

This work aims to examine modification effects of socioeconomic indicators on the association between PM2.5 and annual incidence rate of lung cancer for males in China.

METHODS

We performed a nationwide analysis in 295 counties (districts) from 2006 to 2014. Using multivariable linear regression models controlling for weather conditions and socioeconomic indicators, we examined modification effects in the stratified and combined datasets according to the tertile and binary divisions of socioeconomic indicators. We also extensively investigated whether the roles of socioeconomic modifications were sensitive to the further adjustment of demographic factors, health and behaviour covariates, household solid fuel consumption, the different operationalization of socioeconomic indicators and PM2.5 exposure with single and moving average lags.

RESULTS

We found a stronger relationship between PM2.5 and incidence rate of male lung cancer in urban areas, in the lower economic or lower education counties (districts). If PM2.5 changes by 10 μg/m³, then the shift in incidence rate relative to its mean was significantly higher by 3.97% (95% CI: 2.18%, 4.96%, p = 0.000) in urban than in rural areas. With regard to economic status, if PM2.5 changes by 10 μg/m³, then the change in incidence rate relative to its mean was significantly lower by 0.99% (95% CI: -2.18%, 0.20%, p = 0.071) and 1.39% (95% CI: -2.78%, 0.00%, p = 0.037) in the middle and high economic groups than in the low economic group, respectively. The change in incidence rate relative to its mean was significantly lower by 1.98% (95% CI: -3.18%, -0.79%, p = 0.001) and 2.78% (95% CI: -4.17%, -1.39%, p = 0.000) in the middle and high education groups compared with the low education group, respectively, if PM2.5 changes by 10 μg/m³. We found no robust modification effects of employment rate and urbanisation growth rate.

CONCLUSION

Male residents in urban areas, in the lower economic or lower education counties are faced with a greater effect of PM2.5 on the incidence rate of lung cancer in China. The findings emphasize the need for public health intervention and urban planning initiatives targeting the urban-rural, educational or economic disparities in health associated with air pollution exposure. Future prediction on air pollution-induced health effects should consider such socioeconomic disparities, especially for the dominant urban-rural disparity in China.

Health burdens of ambient PM2.5 pollution across Chinese cities during 2006-2015

With frequent severe haze and smog episodes in Chinese cities, an increasing number of studies have focused on estimating the impact of fine particulate matter (PM_2.5) on public health. However, the current use of national and provincial demographic data might mask regional differences and lead to inaccurate estimations of pollution-related health impacts across cities. We applied the Global Burden of Disease methodology to develop a dataset of premature deaths attributed to ambient PM_2.5 in 129 Chinese cities in 2006, 2010 and 2015, based on the information of baseline mortality rates and population densities at the city level. Our results suggested that ambient PM_2.5 pollution led to 631,230 (95% confidence interval: 281,460-873,800) premature deaths in those cities in 2015, which was similar to that in 2010, but 42.8% higher than that in 2006. The reduction of premature deaths was not as obvious as the improvement in air quality in recent years, primarily owing to the aging Chinese population. For large and medium/small cities, the effects of PM_2.5 abatement on alleviating public health burdens were lower than those for megalopolises and metropolises; however, such large and medium/small cities are at risk of increasing future PM_2.5 pollution levels due to rapid development. Significant differences in PM_2.5-induced premature deaths indicated the need for specific policies to mitigate the health burden of air pollution in different types of Chinese cities.

The association of PM2.5 with airway innate antimicrobial activities of salivary agglutinin and surfactant protein D

Fine particulate matter ≤2.5 μm (PM_2.5) is a prominent global public health risk factor that can cause respiratory infection by downregulating the amounts of antimicrobial proteins and peptides (AMPs). Both salivary agglutinin (SAG) and surfactant protein D (SPD) are important AMPs in respiratory mucosal fluid, providing protection against airway pathogen invasion and infection by inducing microbial aggregation and enhancing pathogen clearance. However, the relationship between PM_2.5 and these AMPs is unclear. To better understand the relationship between PM_2.5 and airway innate immune defenses, we review the respiratory antimicrobial activities of SAG and SPD, as well as the adverse effects of PM_2.5 on airway innate antimicrobial defense. We speculate there exists a dual effect between PM_2.5 and respiratory antimicrobial activity, which means that PM_2.5 suppresses respiratory antimicrobial activity through downregulating airway AMPs, while airway AMPs accelerate PM_2.5 clearance by inducing PM_2.5 microbial aggregation. We propose further research on the relationship between PM_2.5 and these AMPs.

Correlations between PM2.5 and Ozone over China and Associated Underlying Reasons

We investigated the spatial-temporal characteristics of the correlations between observed PM2.5 and O3 over China at a national-scale level, and examined the underlying reasons for the varying PM2.5–O3 correlations by using a chemical transport model. The PM2.5 concentrations were positively correlated with O3 concentrations for most regions and seasons over China, while negative correlations were mainly observed in northern China during winter. The strongest positive PM2.5–O3 correlations with correlation coefficients (r) larger than +0.7 existed in southern China during July, and the strongest negative correlations (r < −0.5) were observed in northern China during January. It was a very interesting phenomenon that the positive PM2.5–O3 correlations prevailed for high air temperature samples, while the negative correlations were generally found in cold environments. Together, the effective inhibitory effect of PM2.5 on O3 generation by reducing photolysis rates and the strong titration effect of freshly emitted NO with O3 contributed to the strongest negative PM2.5–O3 correlations in northern China during January (i.e., in cold environments). The strongest positive correlations in southern China during July (i.e., at high temperature), however, were mainly attributed to the promoting effect of high O3 concentration and active photochemical activity on secondary particle formation.

Seasonal variation and human exposure assessment of legacy and novel brominated flame retardants in PM2.5 in different microenvironments in Beijing, China

Indoor exposure to legacy and novel brominated flame retardants (NBFRs) may cause potential risks to human health. Studies on seasonal variations of indoor PM_2.5-bound BFRs are scant. This study comprehensively investigated the seasonal variations of PM_2.5-bound polybrominated diphenyl ethers (PBDEs) and NBFRs in various indoor environments (i.e. activity room, dormitory, home and office) and outdoor PM_2.5 in Beijing, China over one year. The levels of PBDE (226 ± 108 pg m^-3) were higher than that of NBFRs (27.0 ± 16.0 pg m^-3) in all indoor environments. Decabromodiphenyl ether (BDE-209) and decabromodiphenyl ethane (DBDPE) were the most abundant BFRs. Office showed the highest mean concentrations of Σ₁₅PBDEs (251 ± 125 pg m^-3) and Σ₉NBFRs (33.0 ± 18.0 pg m^-3), which may be related to the higher number density of indoor materials. The concentrations of Σ₉NBFRs and Σ₁₅PBDE in indoor PM_2.5 were found to be significantly higher than those in the corresponding outdoor PM_2.5 (p < 0.05). Two to twenty-fold seasonal variations were observed for levels of PM_2.5-bound BFRs during one year, and indoor concentrations increased slightly during the central-heating period (November 2016-March 2017). Seasonal variations of BFRs could be affected by temperature, relative humidity and concentrations of particle matters. The PM_2.5-bound BFRs concentrations in PM_2.5 were negatively correlated with temperature and relative humidity, while positively correlated with PM_2.5 concentrations (p < 0.05). Atmospheric haze pollution could possibly contribute to higher levels of indoor PM_2.5-bound BFRs. Human daily intake of BFRs via PM_2.5 inhalation showed seasonal differences, and the highest exposure risk occurred in winter. Toddlers were assessed to be more vulnerable to indoor PM_2.5-bound BFRs in all seasons. This study provided the first-hand measurements of seasonal concentrations and human exposure to PM_2.5-bound BFRs in different indoor scenarios in Beijing.

All-cause mortality risk associated with long-term exposure to ambient PM2·5 in China: a cohort study

BACKGROUND

Evidence from cohort studies in North America and Europe indicates that long-term exposure to fine particulate matter (PM_2·5) is associated with an increased mortality risk. However, this association has rarely been quantified at higher ambient concentrations. We estimated the hazard ratio (HR) for all-cause mortality from long-term exposure to PM_2·5 in a well established Chinese cohort of older adults.

METHODS

The Chinese Longitudinal Healthy Longevity Survey (CLHLS) is a prospective cohort study of men and women aged 65 years and older enrolled in 2008 and followed up through 2014 for mortality events. We studied individuals for whom residential locations were available in 2008 for linkage to 1 km grids of PM_2·5 concentrations, derived from satellite remote sensing. Cox proportional hazards models were used to estimate the effect of long-term exposure to PM_2·5 on all-cause mortality, controlling for age, sex, smoking status, drinking status, physical activity, body-mass index, household income, marital status, and education. We then used our results to estimate premature mortality related to PM_2·5 exposure in the population aged 65 years and older in China in 2010.

FINDINGS

13 344 individuals in the CLHLS cohort had data for all timepoints, yielding follow-up data for 49 440 person-years. In a 3-year window, these individuals were exposed to a median PM_2·5 concentration of 50·7 μg/m³ (range 6·7-113·3). The overall HR for a 10 μg/m³ increase in this value was 1·08 (95% CI 1·06-1·09). In stratified analyses, HRs were higher in rural than in urban locations, in southern versus northern regions, and with exposure to lower versus higher PM_2·5 concentrations. Based on the overall HR, we estimated that 1 765 820 people aged 65 years and older in China in 2010 had premature mortality related to PM_2·5 exposure.

INTERPRETATION

Long-term exposure to PM_2·5 is associated with an increased risk of all-cause mortality among adults aged 65 years and older in China, but the magnitude of the risk declines as the concentration of PM_2·5 increases.

FUNDING

National Natural Science Foundation of China, National High-Level Talents Special Support Plan of China for Young Talents, US National Aeronautics and Space Administration, and the Columbia University Global Policy Initiative.

Association of Exposure to Ambient Fine Particulate Matter Constituents With Semen Quality Among Men Attending a Fertility Center in China

Ambient fine particulate matter (PM_2.5) exposure has been linked to decreased semen quality, but the associations between PM_2.5 constituent exposures and semen quality remain unknown. We enrolled 1081 men whose partners underwent assisted reproductive technology procedures in Wuhan, China in 2014-2015, and examined their semen quality. Daily average concentrations of PM_2.5 constituents including 10 metals/metalloid elements and 4 water-soluble ions were continuously determined for 1 week per month at 2 fixed monitoring stations. Linear mixed models were used to examine the associations of exposures to PM_2.5 and its constituents with semen quality. Each interquartile range (36.5 μg/m³) increase in PM_2.5 exposure was significantly associated with 8.5% (95% CI: 2.3%, 14.4%) and 8.1% (95% CI: 0.7%, 15.0%) decrease in sperm concentration and total sperm number, respectively. Antimony, cadmium, lead, manganese, and nickel exposures were significantly associated with decreased sperm concentration, whereas manganese exposure was also significantly associated with decreased total motility. Nonsmokers were more susceptible to PM_2.5 constituent exposures, especially for antimony and cadmium (all P for effect modification <0.05). These findings suggest that PM_2.5 and certain constituents may adversely affect semen quality, especially sperm concentration, and provide new evidence to formulate pollution abatement strategies for male reproductive health.

Temporal variations of PM2.5-bound organophosphate flame retardants in different microenvironments in Beijing, China, and implications for human exposure

In the present study, the temporal distribution of PM_2.5-bound organophosphate flame retardants (OPFRs) was comprehensively investigated in various indoor environments as well as outdoor air in Beijing, China over a one-year period. The mean concentrations of Σ₉OPFRs were 22.7 ng m^-3 and 1.40 ng m^-3 in paired indoor and outdoor PM_2.5, respectively. The concentrations of tri-n-butyl phosphate (TNBP), tris (2-chloroethyl) phosphate (TCEP) and tris (2-chloroisopropyl) phosphate (TCIPP) in indoor PM_2.5 were significantly correlated with those in outdoor PM_2.5. For different indoor microenvironments, mean concentrations of Σ₉OPFRs were in the order of office (29.0 ± 11.7 ng m^-3) > home (24.0 ± 9.4 ng m^-3) > dormitory (19.4 ± 4.9 ng m^-3) > activity room (14.4 ± 3.1 ng m^-3). TCIPP was the most abundant compound in the indoor PM_2.5, followed by TCEP. Significantly higher concentrations of OPFRs were observed in indoor environments with more furnishing, electronics or other materials (p < 0.05). Moreover, lower levels of OPFRs in indoor air were observed at well-ventilated (with higher air exchange rate) indoor sampling sites. Concentrations of Σ₉OPFRs in the activity room, dormitory, homes and outdoor sites generally increased in summer and heating seasons (November 2016 to February 2017). Significant correlations (p < 0.05) were observed between temperatures and mass concentrations of OPFRs with higher vapor pressures, i.e. TNBP, TCEP and TCIPP in all indoor and outdoor samples. Seasonal differences in human exposure were observed and the highest daily exposure dose occurred in summer. Toddlers may suffer the highest exposure risk of PM_2.5-bound OPFRs via inhalation among all age groups. This is one of the very few studies that have revealed the seasonal variation and human exposure of PM_2.5-bound OPFRs in different microenvironments, which shed light on emission sources and fate of OPFRs and potential human exposure pathway.

Estimating mortality burden attributable to short-term PM2.5 exposure: A national observational study in China

Studies worldwide have estimated the number of deaths attributable to long-term exposure to fine airborne particles (PM2.5), but limited information is available on short-term exposure, particularly in China. In addition, most existing studies have assumed that short-term PM2.5-mortality associations were linear. For this reason, the use of linear exposure-response functions for calculating disease burden of short-term exposure to PM2.5 in China may not be appropriate. There is an urgent need for a comprehensive, evidence-based assessment of the disease burden related to short-term PM2.5 exposure in China. Here, we explored the non-linear association between short-term PM2.5 exposure and all-cause mortality in 104 counties in China; estimated county-specific mortality burdens attributable to short-term PM2.5 exposure for all counties in the country and analyzed spatial characteristics of the mortality burden due to short-term PM2.5 exposure in China. The pooled PM2.5-mortality association was non-linear, with a reversed J-shape. We found an approximately linear increased risk of mortality from 0 to 62 μg/m3 and decreased risk from 62 to 250 μg/m3. We estimated a total of 169,862 additional deaths from short-term PM2.5 exposure throughout China in 2015. Models using linear exposure-response functions for the PM2.5-mortality association estimated 32,186 deaths attributable to PM2.5 exposure, which is 5.3 times lower than estimates from the non-linear effect model. Short-term PM2.5 exposure contributed greatly to the death burden in China, approximately one seventh of the estimates from the chronic effect. It is essential and crucial to incorporate short-term PM2.5-related mortality estimations when considering the disease burden attributable to PM2.5 in developing countries such as China. Traditional linear effect models likely underestimated the mortality burden due to short-term exposure to PM2.5.

Air pollution intervention and life-saving effect in China

As a critical air pollutant, PM_2.5 is proved to be associated with numerous adverse health impacts and pose serious challenges to human life. This situation is especially important for China as the most populous and one of the heaviest PM_2.5 polluted country in the world. However, health burden estimations reported for China in previous studies may be biased due to the usage of PM_2.5 concentrations at a coarsely spatial resolution, as well as the ignorance of the spatial discrepancies of parameters (e.g. respiratory rate) employed in the exposure-response function. This study therefore utilized a hybrid remote sensing-geostatistical approach to refine PM_2.5 concentrations at 1 km resolution across mainland China from 2013 to 2017. Meanwhile, nationwide exposure parameters were for the first time introduced to weight the integrated exposure response (IER) function to calculate and spatially reallocate the corresponding PM_2.5-attributable premature deaths at 1 km resolution. Results showed that annually averaged PM_2.5 concentrations in mainland China decreased by 39.5%, from 59.1 μg/m³ in 2013 to 35.8 μg/m³ in 2017. Subsequently, PM_2.5 attributable premature deaths reduced 12.6%, from 1.20 million (95% CI: 0.57; 1.71) in 2013 to 1.05 million (95% CI: 0.44; 1.44) in 2017. This declining trend was found in most parts of China except some areas in Xinjiang, Jilin, and Heilongjiang provinces. As a result, 214,821 (95% CI: 96,675; 302,897) life were saved with an estimated monetary value of US$ 210.14 billion (2011 values). However, it has to be acknowledged that, the central and northern China within priority areas of air pollution control were still experiencing high numbers of premature deaths due to the severe PM_2.5 pollution and high-density population. But more worrying than these priority areas are those Harbin-Changchun Metropolitan Region, City Belt in Central Henan and Yangtze-Huaihe City Belt in non-priority areas, which also have been seriously suffering PM_2.5 attributable premature deaths over 28, 000 cases per year. In conclusion, despite the huge gain in life-saving effects in China over the past five years with the help of air pollution intervention policy, future work on cleaner air and better human health is still strongly needed, especially in non-priority areas of air pollution control.

Air pollution during the winter period and respiratory tract microbial imbalance in a healthy young population in Northeastern China

In order to investigate the relationship between air pollution and the respiratory tract microbiota, 114 healthy volunteers aged 18-21 years were selected during the winter heating period in Northeast China; 35 from a lightly polluted region (group A), 40 from a moderately polluted region (group B) and 39 from a heavily polluted region (group C). Microbial genome DNA was extracted from throat swab samples to study the oral flora composition of the volunteers by amplifying and sequencing the V3 regions of prokaryotic 16S rRNA. Lung function tests were also performed. The relative abundance of Bacteroidetes and Fusobacteria were significantly lower and Firmicutes Proteonacteria and Actinobacteria higher in participants from polluted regions. Within bacteria classes, Bacterioida abundance was lower and Clostridia abundance higher in polluted areas, which was also reflected in the order of abundance. In samples from region C, the abundance of Prevotellaceae, Veillonellaceae, Porphyromonadaceae, Fusobacteriaceae Paraprevollaceae and Flavobacteriaceae were lowest among the 3 regions studied, whereas the abundance of Lachnospiraceae and Ruminococcaceae were the highest. From group A to group C, the relative class abundances of Prevotella, Veillonella, Fusobacterium, Camphylobacter and Capnocytophaga Porphyromonas, Peptostreptococcus and Moraxella became lower in polluted areas. Pulmonary function correlated with air pollution and the oropharyngeal microbiota differed within regions of high, medium and low air pollution. Thus, during the winter heating period in Northeast China, the imbalance of the oropharyngeal microbiota might be caused by air pollution and is likely associated with impairment of lung function in young people.

Analysis of the adverse health effects of PM2.5 from 2001 to 2017 in China and the role of urbanization in aggravating the health burden

In this study, the trend of PM_2.5 concentrations and its adverse health effects in China from 2001 to 2017 are estimated utilizing 1-km high-resolution annual satellite-retrieved PM_2.5 data. PM_2.5 concentrations for most of the provinces/cities remained stable from 2001 to 2012; however, following the issue of the Air Pollution Prevention and Control Action Plan (APPCAP) by the central government of China, a dramatic decrease in PM_2.5 concentrations from 2013 to 2017 occurred. Premature mortality caused by PM_2.5 dropped from 1,078,800 in 2014 to 962,900 in 2017. The PM_2.5 caused 17-year average mortality ranges from 3800 in Hainan Province to 124,800 in Henan Province. The health cost benefits gained by the reduction of PM_2.5 pollution amounted to US $193,800 in 2017 (compared to the costs due to PM_2.5 concentrations in 2013), amounting to 1.58% of the total national GDP. The impacts of urbanization on PM_2.5 concentration and mortality are analyzed. The PM_2.5 concentration and its induced mortality density in dense urban areas are much higher than those in rural areas. The aggravation of PM_2.5 associated premature mortality in urban areas is mainly due to the larger amount of emissions and to urban migration, and 6500 deaths in 2014 could have been avoided were the population ratios in dense-urban/normal-urban/rural areas to be reversed to the ones in 2001. It is recommended that people with respiratory-related diseases live in rural areas, where the pollutant concentration is relatively low.

Ambient fine particulate matter inhibits innate airway antimicrobial activity in preschool children in e-waste areas

Ambient fine particulate matter (PM_2.5) is a risk factor for respiratory diseases. Previous studies suggest that PM_2.5 exposure may down-regulate airway antimicrobial proteins and peptides (AMPs), thereby accelerating airway pathogen infection. However, epidemiological research is scarce. Hence, we estimated the associations between individual PM_2.5 chronic daily intake (CDI) and the levels of the airway AMP salivary agglutinin (SAG), as well as peripheral leukocyte counts and pro-inflammatory cytokines, of preschool children in Guiyu (an e-waste area) and Haojiang (a reference area located 31.6 km to the east of Guiyu). We recruited 581 preschool children from Guiyu and Haojiang, of which 222 were included in this study for a matching design (Guiyu: n = 110 vs. Haojiang: n = 112). Air PM_2.5 pollution data was collected to calculate individual PM_2.5 CDI. The mean concentration of PM_2.5 in Guiyu was higher than in Haojiang, resulting in a higher individual PM_2.5 CDI. Concomitantly, saliva SAG levels were lower in Guiyu children (5.05 ng/mL) than in Haojiang children (8.68 ng/mL), and were negatively correlated with CDI. Additionally, peripheral counts of white blood cells, and the concentrations of interleukin-8 and tumor necrosis factor-alpha, in Guiyu children were greater than in Haojiang children, and were positively associated with CDI. Similar results were found for neutrophils and monocytes. To our knowledge, this is the first study on the relationship between PM_2.5 exposure and innate airway antimicrobial activity in children, in an e-waste area, showing that PM_2.5 pollution may weaken airway antimicrobial activity by down-regulation of saliva SAG levels, which might accelerate airway pathogen infection in children.

Estimation of PM2·5-associated disease burden in China in 2020 and 2030 using population and air quality scenarios: a modelling study

BACKGROUND

Air pollution and its adverse effects on public health remain a considerable problem in China, where policies have been implemented to improve the situation. We aimed to estimate the disease burden associated with particulate matter (PM)_2·5 across China for 2020 and 2030 to identify the populations and regions most at risk, quantify the health benefits of air quality improvement targets, and determine the effect of population growth and ageing on this disease burden.

METHODS

In this modelling study, we investigated premature deaths associated with PM_2·5 across China on the basis of air quality scenarios proposed by the expert group involved in the formulation of the 13th Five-Year Plan for Eco-Environmental Protection and population scenarios based on the Shared Socioeconomic Pathways of the Intergovernmental Panel on Climate Change. We used the integrated exposure-response model used for the Global Burden of Disease Study to estimate the number of PM_2·5-related premature deaths under each scenario.

FINDINGS

The projected health benefits of the air-quality-improving targets are substantial, and could reduce the number of PM_2.5-related premature deaths in China by approximately 129 278 by 2020 and 217 988 by 2030, compared with 2010. However, since China's population is increasing and ageing, the number of PM_2.5-related premature deaths was estimated to increase by 84 102 by 2020 and by 244 191 by 2030, indicating that the health benefits induced by air quality improvements could be offset by the effect of the population increasing in size and ageing.

INTERPRETATION

To reduce the future disease burden in China, targets that are stricter than the interim target and stringent policies to improve air quality and protect public health are needed, especially for at-risk population groups, such as older individuals (aged >55 years) and patients with cardiovascular diseases, particularly in regions with a high disease burden.

FUNDING

National Key Research and Development Program of China, National Natural Science Foundation of China, Beijing Natural Science Foundation, National High-level Talents Special Support Plan of China for Young Talents, and Special Foundation of Basic Science and Technology Resources Survey of Ministry of Science and Technology of China.

Trametes orientalis polysaccharide alleviates PM2.5-induced lung injury in mice through its antioxidant and anti-inflammatory activities

Trametes orientalis polysaccharide (TOP-2) could alleviate PM_2.5-induced lung injury in mice via its antioxidant and anti-inflammatory activities.

PM2.5-related health and economic loss assessment for 338 Chinese cities

China is in a critical stage of ambient air quality management after global attention on pollution in its cities. Industrial development and urbanization have led to alarming levels of air pollution with serious health hazards in densely populated cities. The quantification of cause-specific PM_2.5-related health impacts and corresponding economic loss estimation is crucial for control policies on ambient PM_2.5 levels. Based on ground-level direct measurements of PM_2.5 concentrations in 338 Chinese cities for the year 2016, this study estimates cause-specific mortality using integrated exposure-response (IER) model, non-linear power law (NLP) model and log-linear (LL) model followed by morbidity assessment using log-linear model. The willingness to pay (WTP) and cost of illness (COI) methods have been used for PM_2.5-attributed economic loss assessment. In 2016 in China, the annual PM_2.5 concentration ranged between 10 and 157 μg/m³ and 78.79% of the total population was exposed to >35 μg/m³ PM_2.5 concentration. Subsequently, the national PM_2.5-attributable mortality was 0.964 (95% CI: 0.447, 1.355) million (LL: 1.258 million and NPL: 0.770 million), about 9.98% of total reported deaths in China. Additionally, the total respiratory disease and cardiovascular disease-specific hospital admission morbidity were 0.605 million and 0.364 million. Estimated chronic bronchitis, asthma and emergency hospital admission morbidity were 0.986, 1.0 and 0.117 million respectively. Simultaneously, the PM_2.5 exposure caused the economic loss of 101.39 billion US$, which is 0.91% of the national GDP in 2016. This study, for the first time, highlights the discrepancies associated with the three commonly used methodologies applied for cause-specific mortality assessment. Mortality and morbidity results of this study would provide a measurable assessment of 338 cities to the provincial and national policymakers of China for intensifying their efforts on air quality improvement.

Estimation of PM2.5 mortality burden in China with new exposure estimation and local concentration-response function

The estimation of PM_2.5-related mortality is becoming increasingly important. The accuracy of results is largely dependent on the selection of methods for PM_2.5 exposure assessment and Concentration-Response (C-R) function. In this study, PM_2.5 observed data from the China National Environmental Monitoring Center, satellite-derived estimation, widely collected geographic and socioeconomic information variables were applied to develop a national satellite-based Land Use Regression model and evaluate PM_2.5 exposure concentrations within 2013-2015 with the resolution of 1 km × 1 km. Population weighted concentration declined from 72.52 μg/m³ in 2013 to 57.18 μg/m³ in 2015. C-R function is another important section of health effect assessment, but most previous studies used the Integrated Exposure Regression (IER) function which may currently underestimate the excess relative risk of exceeding the exposure range in China. A new Shape Constrained Health Impact Function (SCHIF) method, which was developed from a national cohort of 189,793 Chinese men, was adopted to estimate the PM_2.5-related premature deaths in China. Results showed that 2.19 million (2013), 1.94 million (2014), 1.65 million (2015) premature deaths were attributed to PM_2.5 long-term exposure, different from previous understanding around 1.1-1.7 million. The top three provinces of the highest premature deaths were Henan, Shandong, Sichuan, while the least ones were Tibet, Hainan, Qinghai. The proportions of premature deaths caused by specific diseases were 53.2% for stroke, 20.5% for ischemic heart disease, 16.8% for chronic obstructive pulmonary disease and 9.5% for lung cancer. IER function was also used to calculate PM_2.5-related premature deaths with the same exposed level used in SCHIF method, and the comparison of results indicated that IER had made a much lower estimation with less annual amounts around 0.15-0.5 million premature deaths within 2013-2015.

Elevated biomarkers of sympatho-adrenomedullary activity linked to e-waste air pollutant exposure in preschool children

Air pollution is a risk factor for cardiovascular disease (CVD), and cardiovascular regulatory changes in childhood contribute to the development and progression of cardiovascular events at older ages. The aim of the study was to investigate the effect of air pollutant exposure on the child sympatho-adrenomedullary (SAM) system, which plays a vital role in regulating and controlling the cardiovascular system. Two plasma biomarkers (plasma epinephrine and norepinephrine) of SAM activity and heart rate were measured in preschool children (n = 228) living in Guiyu, and native (n = 104) and non-native children (n = 91) living in a reference area (Haojiang) for >1 year. Air pollution data, over the 4-months before the health examination, was also collected. Environmental PM_2.5, PM₁₀, SO₂, NO₂ and CO, plasma norepinephrine and heart rate of the e-waste recycling area were significantly higher than for the non-e-waste recycling area. However, there was no difference in plasma norepinephrine and heart rate between native children living in the non-e-waste recycling area and non-native children living in the non-e-waste recycling area. PM_2.5, PM₁₀, SO₂ and NO₂ data, over the 30-day and the 4-month average of pollution before the health examination, showed a positive association with plasma norepinephrine level. PM_2.5, PM₁₀, SO₂, NO₂ and CO concentrations, over the 24 h of the day of the health examination, the 3 previous 24-hour periods before the health examination, and the 24 h after the health examination, were related to increase in heart rate. At the same time, plasma norepinephrine and heart rate on children in the high air pollution level group (≤50-m radius of family-run workshops) were higher than those in the low air pollution level group. Our results suggest that air pollution exposure in e-waste recycling areas could result in an increase in heart rate and plasma norepinephrine, implying e-waste air pollutant exposure impairs the SAM system in children.