Mumbai doctor shares most hazardous time to go for a run in high air pollution: Even 30 minutes can be as bad as smoking

In an interview with HT Lifestyle, Dr Ramkishan Nag, consultant, surgical oncology, HCG Cancer Centre, Borivali, warned against it. According to him, early morning runs, a favourite among fitness enthusiasts, can be particularly hazardous due to stagnant air and high pollution levels.

Early winter mornings: most hazardous time to run

He said, “An early morning run is seen by many Indians as the pinnacle of fitness and discipline, yet in cities where air quality regularly falls into ‘poor’ or ‘severe’ classifications, that revitalising jog can really be detrimental rather than beneficial. Exercising in polluted air significantly increases the amount of toxins inhaled, while its impact on the lungs can be long-lasting.”

According to Dr Nag, “The danger is particularly great in early winter mornings, popular for runners, when smog, vehicle exhaust, and cold, stagnant air trap pollutants at or near ground level. Levels of AQI between 200 and 400 have become disturbingly common in too many Indian cities. This creates an atmosphere in which even a 30-minute outdoor run can expose the respiratory system to as much toxic air as that from smoking a number of cigarettes.”

What happens inside lungs when you run in bad air?

Why does exercise increase your exposure to pollutants? Dr Nag explained that aerobic exercises, such as jogging, increase the body’s oxygen requirement: “To meet this demand, breathing becomes faster and deeper. This increased ventilation draws in more particulate matter, allergens, and toxic gases, such as PM2.5, PM10, nitrogen dioxide, and ozone, deep into the lungs. When you run in polluted air, you are inhaling two to three times more pollutants than at rest. These fine particles penetrate the smallest airways, causing inflammation that may impair lung function over time.”

These concerns are supported by a growing amount of research, he added. “Exposure to particulate matter has been shown to induce bronchospasm, reduce lung capacity, and exacerbate pre-existing respiratory diseases like asthma or chronic bronchitis during exercise. Repeated exposures over a long time could also lead to increased risk for COPD (Chronic obstructive pulmonary disease) and cardiovascular disease,” the surgical oncologist shared.

How runners can protect themselves in high pollution

Runners should adjust their running regimens according to local air quality conditions, Dr Nag said. “If the AQI is greater than 200, do not do intense outdoor exercises; indoor alternatives on a treadmill, gym, or home exercises can replace it. If running outdoors cannot be avoided, use a certified N95 mask, avoid high-traffic roads, and seek greener areas with better air circulation for your workout,” he shared.

Technology can help runners make safer choices

Technology can help, too, he said: “AQI apps provide real-time updates, enabling people to plan safe workout windows. Levels of pollution are generally lower in late mornings and early evenings compared to dawn and dusk.”

Dr Nag added that urban planners and health experts should focus on long-term solutions, including more green cover, cleaner public transportation, and strict emission control policies. He concluded, “Running remains one of the efficient ways to keep fit, yet this has to be offset against the growing menace of pollution. Your workout should strengthen your lungs-not expose them to damage. Thus, with a little planning and awareness, fitness enthusiasts will be able to protect their health while continuing their routines-even in the most difficult urban environments.”

Note to readers: This article is for informational purposes only and not a substitute for professional medical advice. Always seek the advice of your doctor with any questions about a medical condition.