AIR pollution significantly increases inflammatory markers in outdoor athletes, particularly those with allergies, according to new research examining the immune effects of PM2.5 exposure during exercise.
In a randomized crossover study involving 32 male athletes, researchers investigated how exposure to fine particulate matter (PM2.5) during outdoor training affects mucosal immune molecules in saliva. Each participant engaged in 2-hour exercise sessions under both polluted and nonpolluted air conditions, with saliva samples collected before and after workouts.
Analysis revealed that salivary nitric oxide (NO), a marker of airway inflammation, was markedly higher after exercise on polluted days compared to cleaner air days. Additionally, the activity of salivary α-amylase, an indicator of sympathetic nervous system activation, was significantly increased following exercise on polluted days compared to pre-exercise levels. These shifts suggest acute inflammatory and physiological stress responses triggered by poor air quality.
Notably, the effects were more pronounced in athletes with a history of allergic conditions. Among the 16 atopic participants, post-exercise NO levels on polluted days were significantly higher than on nonpolluted days. Although similar trends were observed in non-atopic athletes, their responses were less intense, indicating a potential vulnerability in those with underlying allergic sensitivity.
These findings underscore the immune implications of air quality for individuals who regularly exercise outdoors. The observed immune changes, particularly in those with atopic conditions, raise concerns about the potential long-term impact of repeated exposure to PM2.5 during physical activity. The authors emphasize the need for further studies to determine whether chronic exposure may impair mucosal immunity or increase susceptibility to respiratory illness.
As urban pollution levels continue to challenge public health, this research highlights the importance of environmental considerations in athletic training and suggests that immune monitoring may be warranted for athletes training in polluted environments.
Reference:
Chiang MR et al. Effect of Air Quality on the Mucosal Immune Molecules in Outdoor Male Athletes. J Physiol Investig. 2025. doi:10.4103/ejpi.EJPI-D-25-00010 [Online ahead of print].
