Many people exercise to maintain or improve their health, but not everyone considers the quality of the air they’re breathing while doing so. Whether indoors or outdoors, the air around us can significantly influence the physical benefits we gain—or lose—from working out. Exposure to polluted air during exercise may reduce those health gains and even increase health risks.

The location and ventilation of your gym matter. Is it near a busy intersection or urban center? If so, traffic-related air pollution may be making its way inside through open doors, ventilation systems, or leaks in the building. Some health clubs may not actively monitor air quality, and if there’s no air purification system in place, members might be unknowingly inhaling harmful pollutants while training. Ask your gym whether they use professional-grade filtration and how often systems are maintained.

People who mix gym sessions with outdoor activities like jogging, biking, or walking to work could be exposing themselves to even more pollutants. Exercise near roads or during rush hour may increase contact with nitrogen dioxide, carbon monoxide, ozone, and particulate matter. Urban runners and cyclists are particularly vulnerable to traffic-related emissions, especially during warm afternoons when ozone levels peak.

Exercising changes how your body breathes and processes air. Normally, the nose filters a large portion of airborne particles. But during physical exertion, breathing switches predominantly to the mouth, bypassing this natural filter. This allows more particles—especially ultrafine ones—to penetrate deeper into the lungs.

Scientific studies have shown that:

• During light workouts, the body deposits 3 to 4.5 times more ultrafine particles in the respiratory tract than at rest.
• High-intensity activities can raise this number to 6 to 10 times.
• These particles may trigger inflammation and contribute to cardiovascular stress.
• While exercise helps expel some pollutants more quickly, the initial exposure is still far greater.
• Additionally, heavy breathing reduces the effectiveness of nasal cilia, the tiny hairs that help filter and remove contaminants.

Along with particulates, exercising in polluted areas increases exposure to ozone, carbon monoxide, and nitrogen oxides—all of which can lead to serious health consequences:

• Ozone may decrease lung function and provoke asthma symptoms.
• CO reduces oxygen transport in the body, impacting people with heart conditions the most.
• NOx gases can worsen bronchitis, especially in children and those with respiratory sensitivities.

Absolutely not. Studies agree that staying physically active is better than being sedentary—even in less-than-ideal air conditions. The key is to be strategic:

• Check local air quality forecasts before heading out.
• Avoid high-traffic areas and peak pollution times (like late afternoons or humid days).
• Exercise indoors if the outdoor air is particularly bad, but make sure the indoor space has proper air filtration.
• Ask your gym about their HVAC systems and what level of filtration they provide.

Air pollution doesn’t mean giving up your workout routine—it just means you need to be more informed and selective about when and where you exercise. The right precautions can help you stay fit while minimizing harmful exposure, ensuring that your efforts actually support your health rather than compromise it.