Why those early morning walks are a hazard for you
Data from the CPCB highlights this risk, showing that pollution levels — specifically PM2.5 concentrations — are at their worst during the early morning hours.
The early morning walk, often lauded as a cornerstone of a healthy lifestyle, could be doing more harm than good during Delhi’s pollution season. Stepping out during the early hours may expose you to dangerously high levels of pollution, putting you at risk of respiratory and cardiac problems both in the short and long term, experts warned.

Data from the Central Pollution Control Board (CPCB) highlights this risk, showing that pollution levels — specifically PM2.5 concentrations — are at their worst during the early morning hours. The average PM2.5 exposure at 5am since November 1 was 244µg/m3, and at 7am, it was 232µg/m3.
These figures are nearly four times the national safe standard of 60µg/m3.
PM2.5 refers to airborne particles that are 2.5 microns or smaller in diameter, capable of entering the lungs and even the bloodstream.
Prolonged exposure to PM2.5 has been linked to a range of health issues, including respiratory infections, cardiovascular diseases, and cancer.
Even short-term exposure at high levels can cause symptoms like breathlessness, coughing, headaches, sore throat, and eye irritation.
Doctors emphasise that exercising outdoors in poor air conditions can amplify the harmful effects of pollution on the body.
“When you work out, your oxygen intake increases significantly, and during the early hours, pollutants are trapped close to the ground due to low temperatures and fog,” explained Dr GC Khilnani, chairman of the PSRI Institute of Pulmonary, Critical Care and Sleep Medicine.

“In such conditions, PM2.5 exposure becomes even more hazardous, leading to severe short-term health impacts and contributing to long-term risks like reduced life expectancy, lung diseases, heart conditions, and even skin problems.”
Khilnani added that vulnerable groups, such as children, the elderly, and individuals with pre-existing respiratory or heart conditions, are at even greater risk.
However, even healthy individuals are not immune.
“Lung diseases, cardiac issues, and cancer can develop over time due to chronic exposure to such high pollution levels,” he said.
Dr Arunesh Kumar, a senior consultant in respiratory medicine at Paras Healthcare, echoed these concerns. He recommended avoiding outdoor exercise during early mornings, especially when pollution levels are high.
“The impact is even more pronounced for vulnerable groups like children, elderly, and individuals with pre-existing conditions such as asthma or heart disease. To mitigate these risks, it’s advisable to schedule outdoor activities later in the day when pollution levels are low, or opt for indoor exercises. Using air quality monitoring apps and wearing N95 masks can help mitigate risks,” he said.
Data from November further underscores the problem.
Hourly PM2.5 readings by CPCB show that early mornings consistently record some of the highest pollution levels. On November 11, the PM2.5 concentration reached an alarming 673µg/m3, while the lowest reading between 5am and 7am since November 1 was 55µg/m3 — on December 8 — the only day since November where the PM 2.5 concentration was within permissible limits.
The safest time to be outdoors, data showed, is during the late afternoon or early evening.
The average PM2.5 levels between 5pm and 6pm in November were 130µg/m3 and 133µg/m3, respectively — still over two times the permissible limit but significantly lower than early morning levels.
Sunil Dahiya, lead analyst at the think tank Envirocatalysts, explained that early mornings are particularly hazardous due to a meteorological phenomenon known as inversion.
“We start to see winds becoming calm at night and by midnight, local pollutants have accumulated. These pollutants stay in the air till the sun comes out and wind speeds pick up, making early morning hours fairly dangerous,” Dahiya said, stating that during the afternoon, the sunlight helps in gradual dispersion of pollutants.
As the day progresses, sunlight and increased wind activity gradually disperse pollutants, improving air quality by late afternoon. “The best air quality during the day is typically observed around 5pm, before pollution starts accumulating again with the evening drop in temperature,” Dahiya added.

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