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Tuesday, Oct 15, 2019

Tackle air pollution and breathe life into your walks

With 22 out of the world’s 30 most polluted cities being in India, is it safe to take prolonged walks outdoors?

wellness Updated: Oct 05, 2019 18:03 IST
Natasha Rego
Natasha Rego
Hindustan Times
According to a 2016 study by the University of Cambridge, even in a city like Delhi, you would have to walk outdoors for six hours and fifteen  minutes a day for the negative effects of pollution to outweigh the benefits of walking.
According to a 2016 study by the University of Cambridge, even in a city like Delhi, you would have to walk outdoors for six hours and fifteen minutes a day for the negative effects of pollution to outweigh the benefits of walking. (Raj K Raj/HT PHOTO)
         

If you live in a big Indian city, the idea of running along a wooded path, breathing crisp clean air may well be the stuff of fantasy. India is home to 22 of the world’s 30 most polluted cities, according to a list by IQAir AirVisual and Greenpeace. So does the risk of walking outdoors in India’s cities outweigh the benefits?

What happens during a brisk walk

You breathe faster and inhale deeper, often with an open, panting mouth.

These deep and rapid breaths are meant to infuse your bloodstream with more oxygen. But you also take in more microscopic particles and hazardous gases from the atmosphere into your lungs.

This triggers hyperactivity of the airways, leading to coughs and sneezes.

Breathing through the mouth means you miss out on the basic filtering functions of the nasal passage too.

What you can do
  • Exercise indoors as much as you can. If must step out for your morning or evening walk, keep an eye on the Air Quality Index, which monitors the density of eight pollutants commonly found in cities.
  • Distribution of pollutants are not uniform across large cities, so look for area-specific readings.
  • Try to find quiet and clean paths that are away from heavily trafficked roads.
  • If the park or ground you choose to walk in is near the street and you can’t avoid the exhaust from vehicles, consider using a mask that has proven to adequately filter PM2.5 particles adequately, and also fits snugly into the contours of your face.

You end up inhaling carbon monoxide through active and passive smoking, which decreases the amount of oxygen in the lungs, leading to irritability and tiredness.

“So exercising in the polluted outdoors results in lesser gas exchange in the lungs and more fatigue than exercising in the gym,” says Dr Amit Gawande, a chest physician with a number of hospitals in Mumbai.

But is it really harmful?

A 2016 University of Cambridge study suggests that the benefits of walking outweigh the negative effects from pollution. The paper, Can air pollution negate the health benefits of cycling and walking, states that only 1 per cent of cities have air pollution levels high enough to make daily walking hazardous.

The study says that, for a city like Delhi, the tipping point (the length of time after which there was no further health benefit) was 90 minutes of walking per day. The breaking point (the point at which exposure would be harmful) is six hours and 15 minutes per day.

In Delhi, you would need to cycle over five hours per week before the pollution risks would outweigh the health benefits, study leader Dr Marko Tainiio, was quoted as saying in The Guardian.

That’s not all

What the study doesn’t consider, Dr Gawande points out, is the exposure to air pollution in a person’s daily routine. If you have an outdoor job, then surely any amount of additional time outdoors, even to exercise, isn’t a good idea.

“The study also does not explain why we have an increase in COPD (a lung disease predominantly affecting smokers) among the capital’s non-smokers,” he observes. He says we’ll need more data to confirm any direction connection to air pollution.

First Published: Oct 05, 2019 18:03 IST

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