Researchers from Xi ‘an Jiaotong University have made a new breakthrough in the field of air pollution and human health

Air particulate matter pollution is currently one of the primary environmental risk factors confirmed in the assessment of the global burden of disease. In 2013, The State Council promulgated the “Action Plan for the Prevention and Control of Air Pollution” (hereinafter referred to as the “Ten Measures for Air Pollution Control”), and since then, the air quality in China has improved significantly. At present, worldwide, there is still a lack of detailed evaluations covering the main components and major systemic disease outcomes for the health benefits of the population with large-scale regional air quality improvement, and the contribution roles of different components in the primary air pollutant – fine particulate matter (PM2.5) remain unclear. The World Health Organization (WHO) and various countries still lack research evidence for formulating air quality guideline limits for specific components of PM2.5, which restricts the effective prevention and control of health risks caused by major environmental risk factors.

In response to the above scientific issues, Professor Wu Shaowei’s team from the School of Public Health at Xi ‘an Jiaotong University systematically quantified the health benefits of the population caused by the improvement of air quality after the implementation of the “Ten Measures for Air Pollution Control” in China from 2013 to 2017 from the perspective of hospitalization risk, and found that black carbon is the main contributor to the improvement of population health benefits caused by PM2.5 pollution.

This study was based on the daily hospitalization records of the urban population in 292 prefecture-level and above cities in China from 2013 to 2017, and included 10 major categories of diseases in the respiratory, cardiovascular, mental/neurological and renal systems and the 14 major disease subtypes they contained. The spatio-temporal deep forest model was applied to simulate the daily average concentrations of outdoor air PM2.5 and its six main components (including black carbon, sulfate, nitrate, ammonium, chloride ions, and organic particulate matter) during the study period. Through a two-stage case-cross study design, the exposive-response relationship between PM2.5 and its main components and the hospitalization risk of different diseases was established. Explore and test the independent effects of the main components of PM2.5 by constructing multiple models; By calculating the degree of decline in the proportion of annual hospitalizations attributable to exposure to PM2.5 and its key components during the implementation of the “Ten Measures for Air Pollution Prevention and Control” from 2013 to 2017, the health benefits of the reduced PM2.5 population were quantified. Further, based on the above expoor-response relationship and the cumulative reduction levels of PM2.5 and its main components during the implementation of the “Ten Measures for Air Pollution Prevention and Control”, quantify the real population health benefits of the implementation of the “Ten Measures for Air Pollution Prevention and Control” (expressed in terms of the number of hospitalizations for different diseases that can be avoided).

The research results show that exposure to PM2.5 and its main components is significantly associated with an increased risk of hospitalization for various major diseases. The impact of black carbon exposure on the hospitalization risk of different diseases is generally stronger than that of PM2.5. Among the different main components of PM2.5, only black carbon has a stable impact on the hospitalization risk of different diseases in multiple analytical models, suggesting that the health hazards of black carbon have strong independence and are the main contributing components among the main components of PM2.5 to its health hazards.

The implementation of the “Ten Measures for Air Pollution Control” from 2013 to 2017 significantly reduced the concentration of PM2.5 and its main components in outdoor air. With the annual decrease in the concentrations of PM2.5 and black carbon, the proportion of hospitalizations attributed to PM2.5 and black carbon also shows a significant downward trend (Figure 1). The relative decrease in the average annual attributable percentage of hospitalizations for different diseases corresponding to the reduction in PM2.5 and black carbon concentrations (based on 2013 to assess the change in 2017 compared to 2013) was 30.00% and 21.14% respectively, among which the decrease in the number of hospitalizations due to depression was the largest. There are certain spatial distribution differences in the health benefits of the population affected by the improvement of air quality. Compared with 2013, the greater the health benefits of the population in cities or geographical areas where the improvement of air quality is more obvious. The reduction in PM2.5 and black carbon concentrations brought about by the implementation of the “Ten Measures for Air Pollution Prevention and Control” from 2014 to 2017 led to the highest number of avoidable hospitalizations for target diseases among the urban population involved in the study. Lower respiratory tract infections, coronary heart disease and stroke were the most common. If the sum of avoidable hospitalizations for different system diseases was calculated, cardiovascular diseases were the most common (Figure 2).

 

 

Figure 1. The trend of the annual absolute attribution percentage changes in the number of hospitalizations for different diseases corresponding to the reduction of outdoor air PM2.5 and black carbon concentrations in 292 cities of China from 2013 to 2017

 

Figure 2. Compared with 2013, the estimated number of hospitalizations for different diseases that could be avoided by the urban population in 292 cities of China during the period from 2014 to 2017 due to the reduction of outdoor air PM2.5 and black carbon concentrations

Previous studies have found that as of 2019, 99% of the world’s population still lived in areas that did not meet the WHO’s guideline for air quality (an annual average PM2.5 concentration of 5 μg/m³). The latest data released by China’s Ministry of Ecology and Environment shows that in 2024, the average concentration of PM2.5 in 339 prefecture-level and above cities across the country will be 29.3 μg/m³, meeting the WHO air quality transition period Level I standard (35 μg/m³), but there is still a huge gap from the above-mentioned air quality guidance value. It is indicated that the task of air pollution control in our country still has a long way to go. This study was the first to systematically depict the spatio-temporal map of population health benefits from the improvement of PM2.5 and its main component pollution status in a large area from the perspective of hospitalization risk. It revealed the significant promoting effect of PM2.5 control on public health levels and found that black carbon is the main contributing component to the improvement of population health benefits by PM2.5 pollution. China’s “Ten Measures for Air Pollution Control” has successfully and significantly reduced the concentration of PM2.5, the primary outdoor air pollutant, and its main components within just a few years by setting clear key governance areas and regional target limits, and implementing regional joint prevention and control and multi-departmental collaboration. This has achieved remarkable health benefits for the population. However, similar health benefits in developed countries in Europe and America usually require 20 to 30 years of governance to be achieved.

The above research findings provide important evidence based on real-world scenarios for further promoting the precise governance of air pollution and the prevention and control of major environmental health risks among the population, and contribute Chinese wisdom to the global governance of air pollution. This study suggests that in the process of further promoting precise air pollution control, it is necessary to pay attention to the health risks to the population of the main contributing components of PM2.5 (such as black carbon, mainly derived from incomplete combustion of carbon-containing fuels such as oil, coal and biomass), integrate multi-level research evidence, and promote and refine the formulation of relevant environmental air quality standard limits. Strictly control the emissions from relevant pollution sources. Furthermore, research has found that there is regional heterogeneity in the health benefits of improved air quality among the population. In the future, targeted air pollution control policies should be further formulated in combination with factors such as the economic development characteristics, pollution distribution characteristics, and pollutant sources of different regions to reduce the above-mentioned regional heterogeneity. Taking all the above measures into account will contribute to the realization of the goals of “Beautiful China”, “Healthy China” and even global air pollution control.

The related research results are titled “Hospital admissions attributable to reduced air pollution due to clean-air policies in China”. It was published in the top international medical journal Nature Medicine on March 14, 2025. Professor Wu Shaowei from the School of Public Health, Xi ‘an Jiaotong University, is the lead corresponding author of the above-mentioned paper, and Associate Professor Liu Yuewei from the School of Public Health, Sun Yat-sen University, is the co-corresponding author of this article. Liu Huimeng, a 2022 doctoral student from the School of Public Health at Xi ‘an Jiaotong University, and Lei Jian, an assistant professor, are the co-first authors of this article. This research was supported by the National Natural Science Foundation of China, the China Postdoctoral Science Foundation, the Basic Research Operating Expenses of Chinese Universities, and other projects.