Nearly one-third of asthma cases linked to air pollution

A recent study has provided compelling evidence that long-term exposure to fine particulate matter, known as PM2.5, is a significant risk factor for asthma in both children and adults. 

Drawing on data involving approximately 25 million people across the globe, the research, led by the Max Planck Institute for Chemistry, suggests that PM2.5 exposure is responsible for nearly 30% of new asthma cases worldwide. 

The study highlights the critical need for stricter air quality regulations to protect public health.

A growing health concern

Asthma, a chronic respiratory disease affecting around 4% of the world’s population, causes recurring symptoms like wheezing, coughing, and shortness of breath. Currently, over 30 million new asthma cases arise each year, significantly impacting quality of life. 

However, despite extensive research, the link between air pollution, specifically PM2.5, and asthma has been a topic of debate, with earlier studies offering mixed results. 

This comprehensive study, led by Dr. Ruijing Ni and published in the journal One Earth, consolidates evidence to definitively associate PM2.5 with asthma, providing new insights into the health risks of air pollution.

Link between PM2.5 and asthma

The international team analyzed data from 68 studies conducted across 22 countries, including North America, Western Europe, East Asia, South Asia, and Africa. 

By examining such a wide array of epidemiological data, the researchers found a clear correlation between long-term PM2.5 exposure and asthma risk, with a particularly heightened risk in children.

“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,” Ni explained. 

“In Germany, for instance, PM2.5 exposure may have been responsible for 11% of new asthma cases, affecting approximately 28,000 people. We also find that the risk of asthma associated with PM2.5 is much higher in children than in adults, reflecting the age-related vulnerability.”

The study’s findings align with biological insights into children’s respiratory systems. 

Since the lungs and immune system typically mature fully only in early adulthood, children are particularly susceptible to the oxidative stress, inflammation, and respiratory sensitization that air pollution can trigger – all of which are conditions linked to asthma development.

Asthma risk across ages

Utilizing this extensive dataset, the researchers created exposure-response curves to model how PM2.5 exposure impacts both childhood and adult asthma risk. 

These curves are vital for public health studies, showing the relationship between exposure levels and their health effects—in this case, the risk of asthma.

“This initiative is important for quantifying global health effects of air pollution,” said professor Yuming Guo from Monash University, noting that the curves incorporate data from countries with different income levels and varying degrees of pollution, ensuring the findings have global relevance.

Significant health burden 

People in low- and middle-income countries (LMICs) generally face higher levels of air pollution and, consequently, a higher incidence of PM2.5-related health impacts. 

Historically, however, most PM2.5 health studies have been conducted in high-income regions like North America and Europe. 

This disparity introduces challenges when generalizing findings from wealthier nations to LMICs, given differences in air pollution sources, healthcare quality, and population demographics.

By including evidence from LMICs, the study mitigates these limitations, allowing for more accurate estimates of asthma burden from PM2.5 exposure on city, regional, and global scales. 

Such comprehensive data can help policymakers in different regions gauge the potential health benefits of reducing PM2.5 through various air quality policies.

Protection from air pollution and asthma 

In response to the study’s findings, lead researcher Yafang Cheng, the director of the Aerosol Chemistry Department at Max Planck, emphasizes the importance of regulatory action and personal safety practices. 

“Our findings highlight the urgent need for policymakers to enforce stringent legislation to continuously combat air pollution,” Cheng explained, adding that individual measures like wearing masks can also help people lower their risk of asthma from PM2.5 exposure.

This study provides essential evidence for health organizations, governments, and individuals alike to address the global health threat posed by PM2.5 air pollution. 

As asthma cases continue to climb, the insights from this research highlight the critical need for both preventive measures and robust policy to mitigate air pollution and protect vulnerable populations.

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