Review highlights the health hazards of air pollution in China

Globally, air pollution is a major public health hazard. A key air pollutant linked to health risks is ambient fine particulate matter (PM_2.5), which consists of minute particles, sized less than or equal to 2.5 μm, suspended in the air.

According to the WHO, annual PM_2.5 levels should not exceed 5 μg/m³. However, the current PM_2.5 levels in China far exceed this standard and are responsible for approximately 1.4 million PM_2.5-related excess deaths annually. Even as the country steadily works towards reducing its PM_2.5 footprint, understanding the latest trends in the epidemiology of PM_2.5-related diseases, especially cardiopulmonary diseases, is desirable.

Through comprehensive collaborative efforts, researchers from the Chinese Center for Disease Control and Prevention have now summarized the latest epidemiological advances related to the cardiopulmonary effects of PM_2.5 in the Chinese population. Their review, published in the Chinese Medical Journal, focuses on how PM_2.5 affects the mortality, morbidity, and risk factors for cardiovascular and respiratory diseases.

Explaining the rationale for this review, corresponding author Dr. Xiaoming Shi says, "Compared with other diseases, cardiopulmonary disease is the leading cause of mortality and morbidity associated with PM_2.5. Over the last decade, most studies have found that PM_2.5 is associated with morbidity, mortality, and risk factors for cardiopulmonary disease."

For the review, the researchers used data from recent large-scale, multi-center studies from China to account for the effects associated with both short-term and long-term exposure to PM_2.5.For instance, one time-series study based on mortality data from 130 counties in China revealed that the risk of death from cardiocerebrovascular diseases increases by 0.12% for every 10 μg/m³ increase in PM_2.5 levels.

The review reveals that PM_2.5 increased the risk of developing cardiovascular disease, including ischemic heart disease, heart failure, arrhythmia, and ischemic stroke, as well as risk of hospitalization due to cardiovascular causes. Changes in functional index and biomarkers such as heart rate, blood pressure, cholesterol levels, and inflammatory molecules could indicate increased risks.

Similarly, every 10 μg/m³ increase in PM_2.5 concentration was linked to a 1.68% increase in the risk of respiratory mortality. Increases in PM_2.5 levels were also found to be associated with the hospitalization rate for respiratory diseases and pediatric respiratory outpatient visits. The acute effects of PM_2.5 were found to be associated with functional outcomes such as peak expiratory flow and the forced expiratory volume or capacity.

The authors use this evidence to propose a list of intervention measures against the effects of ambient PM_2.5 on cardiopulmonary health. They suggest government interventions to improve industrial emission standards, upgrade industrial boilers, adopt cutting-edge industrial technology to reduce emissions, and promote clean fuels for residential use.

Together, these efforts could reduce both PM_2.5 pollution and its health burdens, in line with China's 14th Five-Year Plan and sustainable development goals. On the personal front, use of air purifiers and masks can protect people from the hazards of PM_2.5, especially if they live in areas with high PM_2.5 levels.

Elaborating on the prospects, Dr. Shi says, "The Chinese government has formulated carbon neutrality goals to reach a peak as soon as possible (before 2030), achieve rapid emission reduction by 2030 to 2050, and net-zero emissions by 2050 to 2060. Clean air action depends on effective supervision, inter-departmental cooperation to promote supervisory work, and the strict implementation of actions and requirements."

In short, by documenting the latest epidemiological evidence, this review can serve as a key guide for identifying targets of PM_2.5 reduction and health improvement in China. It also underscores the need for additional research in several areas, including the identification of highly sensitive biomarkers and pathogenic effects of PM_2.5 constituents on health.