Run today, pay later? What the haze does to runners

Pollen droplets from vegetation fires carry fine particles called PM2.5, which can deeply penetrate the lungs when inhaled. Running demands more rapid, deeper breathing than resting, so hazy conditions expose runners to heightened amounts of this harmful air. During haze exposure, individuals may experience coughing, wheezing, irritated eyes, and shortness of breath.

For those with pre-existing heart or lung diseases, respiratory conditions worsen, and children, older adults, and pregnant women are especially vulnerable. A study in London revealed that healthy seniors and those with chronic lung or heart disease benefited more from walking in cleaner air versus a polluted environment. While a single hazy run does not lead to long-term illnesses, repeated training in polluted air increases cumulative exposure.

Health authorities recommend avoiding outdoor activities when the Air Pollutant Index (API) exceeds 100, and those with asthma or respiratory symptoms should take extra precautions. Indoor workouts like treadmill sessions, stationary cycling, or strength training with filtered air can maintain fitness levels while minimizing exposure.

Maintaining clean indoor air through air purifiers and avoiding indoor sources of pollution is crucial. Race organizers should have policies in place to postpone events when the API surpasses 100, monitor readings during events, and provide medical support and clear emergency plans. Recognizing when to move workouts indoors or postpone races is essential for maintaining a healthy running culture while addressing the risks posed by polluted air.