Air pollution is widely known to cause respiratory diseases like asthma and chronic obstructive pulmonary disease (COPD), but its role in lower respiratory infections—such as pneumonia and bronchitis—is less understood, especially in adults.
A new study from the Barcelona Institute for Global Health (ISGlobal) has now provided strong evidence that air pollution significantly increases hospital admissions for these infections, particularly among older adults and those with underlying health conditions.
The research, published in Environment International, examined how long-term exposure to common air pollutants—fine particulate matter (PM2.5), coarse particulate matter (PM10), nitrogen dioxide (NO2), and ozone (O3)—affects the likelihood of severe lung infections requiring hospitalization.
The study found that even at pollution levels considered safe by current European Union air quality standards, the risk of hospitalization increased.
Large-Scale Study on Air Pollution and Lung Infections
To investigate the impact of air pollution, researchers analyzed health data from 3.8 million adults in the COVAIR-CAT cohort, a database based on the Catalonia health system, which includes a total of 7.7 million people.
The study focused on the period between 2018 and 2020, measuring air pollution levels at participants’ homes and tracking hospital admissions for lower respiratory infections, influenza, and pneumonia.
Using detailed statistical models, the researchers were able to determine the link between air pollution levels and hospitalizations. Their findings were clear: people exposed to higher levels of PM2.5, PM10, NO2, and O3 were more likely to be hospitalized for lung infections.
Who Is Most at Risk?
The study identified several groups that are particularly vulnerable to the effects of air pollution.
- Older Adults (65+ Years Old): People in this age group had nearly three times the risk of hospitalization for lower respiratory infections compared to younger individuals.
- Men: Exposure to pollutants like NO2, PM2.5, and PM10 was linked to a 50% increase in hospitalizations among men, whereas the increase in women was only around 3%.
- People with Hypertension and Other Underlying Conditions: Those with existing health problems, particularly high blood pressure, were at a greater risk of serious lung infections when exposed to polluted air.
Even though the study also examined hospitalizations for influenza and pneumonia, the associations with air pollution were slightly weaker for these conditions. Researchers believe this could be because vaccines are available for influenza and many forms of pneumonia, reducing the severity of these infections in vaccinated individuals.
Calls for Stricter Air Quality Standards
One of the most concerning aspects of the study is that the link between air pollution and lung infections was observed even at pollution levels below the current EU air quality limits. This suggests that even so-called “safe” levels of air pollution still pose a significant health risk.
“It is crucial to adopt stricter air quality standards,” said Anna Alari, the study’s first author and a researcher at ISGlobal. “More ambitious measures to reduce air pollution would decrease hospital admissions and protect vulnerable populations.”
Senior author Cathryn Tonne echoed this concern, emphasizing the importance of reducing air pollution exposure, particularly for high-risk groups.
Implications and Next Steps
This study adds to the growing evidence that air pollution harms lung health in more ways than previously thought. While past research has focused on its role in chronic diseases, these new findings highlight how pollution directly contributes to severe respiratory infections that require hospitalization.
The results suggest that policymakers should consider stricter air quality regulations and expand efforts to protect people at higher risk. Improving air quality could significantly reduce hospital admissions, lower healthcare costs, and improve overall public health, especially for older adults and those with pre-existing conditions.
As researchers continue to study the long-term effects of air pollution, it is becoming increasingly clear that cleaner air is not just about reducing chronic illness—it can also prevent severe, life-threatening infections.
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The research findings can be found in Environment International.
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