Physical activity
Is it safe to exercise when there is high air pollution?
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Ainhoa Pérez
Alumni
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MPH, MSc.
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A recent systematic review of studies has analyzed the effect of physical activity on health in environments with high air pollution. The evidence suggests that its protective effects are maintained.
PATHOPHYSIOLOGY AND MECHANISMS
Air pollution is one of the leading causes of death worldwide, with an estimated 7 million premature deaths each year, mainly from associated respiratory, cardiovascular, and cerebrovascular diseases. Among the most relevant pollutants are fine particles (PM2.5), nitrogen dioxide (NOâ‚‚), and ozone, which cause systemic inflammation, oxidative stress, and endothelial dysfunction. Physical activity is consistently associated with a lower risk of cardiovascular, respiratory, and oncological diseases through mechanisms such as reduced systemic inflammation, improved cardiovascular and respiratory function, and improved immune system function. However, it has been suggested that exercise in polluted environments could increase the absorption of toxins by increasing ventilatory volume, posing health risks.STUDY
A systematic review and meta-analysis (Martin et al., 2025) investigated the results of eight cohort studies in different countries, which included more than 1.4 million adults, with follow-ups ranging from 10 to 25 years. Five studies analyzed all-cause mortality, and three analyzed specific causes (cardiovascular, respiratory, and oncological). Exposure to pollutants was estimated using spatiotemporal models based on satellite data, monitoring stations, and statistical tools, mainly focused on fine particle exposure analysis. Physical activity was measured using questionnaires and classified according to metabolic intensity (METs). Three main comparisons were made: people exposed to pollution without exercising, active people in unpolluted environments, and active people in polluted environments. The models were adjusted for clinical and sociodemographic variables.MAIN RESULTS
Exposure to air pollution without physical activity was associated with an increased risk of mortality, increasing with higher levels of pollution. Conversely, even in environments with high exposure to pollutants, physical activity was associated with a reduction in mortality compared to those who remained inactive, with the protective effect observed at different levels of physical activity. Similarly, a protective relationship between physical exercise and low pollution environments was found. There is high heterogeneity between studies, although the certainty of the evidence (GRADE) was high for the main effect of physical activity in environments with air pollution, and moderate for most secondary outcomes.CONCLUSION AND CLINICAL RELEVANCE
In conclusion, this meta-analysis confirms that physical activity reduces mortality even in contexts with high air pollution. Although exposure to pollutants increases the risk of death, exercise retains its protective effect, with magnitudes comparable to those observed in unpolluted environments. No significant dose-response relationship was found between exercise level and mortality reduction in polluted environments, although benefits were observed even with low levels of physical activity. However, at the individual level, it is recommended to seek out environments with good air quality for exercise, such as parks away from traffic. The main limitations include high methodological heterogeneity, poor characterization of the type of physical activity or specific pollutant, and the lack of objective measures. Although satellite data were used, indirect estimation of environmental exposure could introduce classification biases. Despite these limitations, the findings for the different subgroups are consistent. Future studies should incorporate objective measures, biomarkers, and integrate the role of urban infrastructure in exposure and exercise practice.
#physicalexercise #sport #airquality #environmentalpollution #pollution #nature
References:
Martin, L et al, 2025. Physical activity, air pollution, and mortality: A systematic review and meta-analysis. Sports Medicine - Open, 11(35). https://doi.org/10.1186/s40798-025-00830-z
* The news published on studies do not represent an official position of ICNS, nor a clinical recommendation.
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