Asthma is currently an incurable disease that seriously impairs quality of life, with recurring symptoms such as wheezing, cough and difficulty breathing. Currently, about 4 percent of the world’s population suffers from asthma, and more than 30 million new cases emerge each year. Evidence suggests that long-term exposure to fine particulate matter (PM) air pollution2.5) is a major risk factor for developing asthma. However, inconsistencies in findings from previous epidemiological studies have left this potential health risk open to debate, with some studies seeing an increased risk while others found no association.
To resolve this controversy, Dr. Ruijing Ni, first author of the study published today in the journal One Earthand colleagues at the Max Planck Institute for Chemistry have conducted a comprehensive global meta-analysis with researchers from China, the US and Australia. The research team determined data from 68 2019 epidemiological studies conducted in 22 countries, including those in North America, Western Europe, East Asia, South Asia and Africa. They conclude that there is now sufficient evidence with a high level of confidence to support an association between long-term exposure to environmental particles2.5 and asthma.
11 percent of new asthma cases in Germany are attributable to particles
“We estimate that globally in 2019, almost a third of asthma cases are attributable to long-term PM2.5 exposure, corresponding to 63.5 million existing cases and 11.4 million new cases. In Germany, pollution may have been responsible for 11 percent of new asthma cases, corresponding to 28,000 people. We also found that the risk of asthma associated with PM2.5 is much higher in children than in adults, reflecting age-related vulnerability,” says Dr. Ni.
Typically, full maturation of lung and immune function is completed gradually until early adulthood. As a result, children may be more susceptible to exposure to air pollution, which can lead to airway oxidative stress, inflammation and hyperreactivity, as well as changes in immune responses and respiratory sensitization to allergens. All of these factors play a role in the development of asthma.
Additionally using these data, the research team established exposure-response curves for both childhood and adult asthma. These curves are widely used to quantitatively assess health risks by illustrating the relationship between the level of exposure to a particular substance, for example, PM2.5 and the magnitude of the effect that produces, for example, risk of asthma. Exposure-response curves were determined incorporating evidence from countries and regions of various income levels, which capture global variation in PM.2.5 exposure. “This initiative is important to quantify the effects of air pollution on global health,” says Professor Yuming Guo, an epidemiologist at Monash University.
Countries with different income levels and particle pollution considered
Populations in low- and middle-income countries (LMICs) are typically exposed to higher concentrations of air pollution and bear a greater burden of PM.2.5. In contrast, research on the health effects of PM2.5 has been limited in these regions previously, with most studies conducted in North America and Western Europe. Consequently, attempting an evaluation of the global impact of PM on health2.5 Exposure requires extrapolating exposure-response associations observed in high-income countries to low- and middle-income countries. The approach can introduce significant uncertainty due to differences in air pollution sources, health systems and demographic characteristics between high-income countries and LMICs.
The inclusion of evidence from several LMICs mitigates the limitation in the approach and allows exposure-response curves to be applicable to assess the attributable burden of asthma at the city scale to a global scale, as well as the health benefits of asthma associated with reducing air pollution, for example, health. benefits realized from policy-driven air pollution reductions in different scenarios.
“Our findings highlight the urgent need for policymakers to implement strict legislation to continually combat air pollution, while personal protective measures, such as the use of masks, can also help reduce individual exposure and mitigate risk.” of asthma,” emphasizes Professor Yafang Cheng, the corresponding author of the study and director of the Max Planck Institute of Chemistry.
The study was carried out by researchers from the Max Planck Institute of Chemistry (Germany), the Institute of Atmospheric Physics of the Chinese Academy of Sciences (China), the University of Washington (USA) and Monash University (Australia).