The benefits of exercise generally outweigh the risks of air pollution. Still, by adopting some methods we can avoid coming in contact with polluted air.
Recently I went out for a run in the morning. Stopped to cross the road, then a van came and parked near me. I could not stop myself from inhaling the dark smoke coming out of its silencer.
I live in London and I like cycling and running. My daily commute also includes cycling. That's why I often get stuck behind vehicles while waiting for the traffic light to change.
Coughing because of the polluted air, I often wonder whether exercising on polluted roads is doing me more harm than good?
Here we will learn about its dangers and benefits.
We will also understand how to protect ourselves from polluted air while exercising in cities.
What's in the air you're breathing?
Everyone knows that air pollution is related to long-term diseases like heart disease, respiratory problems and cancer. This also increases the risk of death at an early age.
According to the World Health Organization, 99 percent of the world's population breathes polluted air. Because of this, 67 lakh people die prematurely every year.
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Audrey de Nazel, associate professor at Imperial College London, studies the effects of pollution on exercise. He says that air pollution affects almost every part of our body.
She says, "Earlier we thought that it caused only respiratory diseases. But it is also related to heart diseases, diabetes, impact on thinking ability and reproductive health."
One of the biggest concerns is PM 2.5. These are very small particles, whose size is only 2.5 micrometers.
These fine particles are about 30 times smaller than the width of a human hair. The pollution emitted from vehicles releases them directly into the air. These can reach deep inside our lungs. From there they can mix with the blood and spread throughout the body.
Over time, the accumulation of these particles in the body can also affect the brain.
harm from nitrogen dioxide
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A review published in the year 2025 looked at 51 studies. A team of researchers analyzed data related to more than 2.9 crore people.
They found an association between three types of air pollution and an increased risk of Parkinson's disease. PM 2.5 was also included in these.
Haneen Khrais, co-author of the study and an epidemiologist at the University of Cambridge, says, "When the particles are so small, they can cross the blood-brain barrier. They can damage the blood vessels and this protective layer. In addition, these particles can also reach inside the brain."
But other pollutants are also present in the air.
We also breathe nitrogen dioxide while exercising on busy roads or in cities. In this review, its relation was also found with increased risk of Parkinson's disease.
It is believed that nitrogen dioxide can cause swelling in the lungs. In the long run, this can affect the development of the lungs and their ability to function.
Apart from this, the air also contains sulfur dioxide, ammonia, carbon monoxide and ozone formed near the ground.
When we run, cycle or do vigorous exercise, our breathing becomes faster and deeper. This means that we inhale more polluted air while running than while walking.
People who do vigorous exercise while covering the same distance get more amount of toxic particles in their lungs.
But you may be surprised to know that even sitting in a car does not provide complete protection from air pollution.
Urban people should be careful
Dr Rudy Sinhare, a specialist in respiratory diseases and lung cancer at Imperial College London NHS Trust, says: "When cycling, your exposure to pollution is less than that of a person sitting in a car. When cycling, you are moving forward and there is also a little more air moving around."
Pollution is not caused only by vehicles running on the road. The underground rail services of cities such as London and New York can also contain high levels of fine particles.
Most of these particles are metal dust, which is produced by friction between wheels, railway tracks and brakes. The benefits outweigh the disadvantages.
"The good thing is that even in polluted cities, the benefits of exercise outweigh the risks," says De Nzel.
According to him, exercise itself can help protect our body from the effects of pollution.
In a 2016 study, De Nazel and his colleagues tried to understand this.
In this study based on computer models, they estimated that the health benefits of walking and cycling outweigh the harm caused by polluted air.
Only in areas with high pollution may the risks of prolonged exercise be equal to or outweigh the benefits. These include the world's most polluted cities like Delhi of India.
Exercising even in polluted areas reduces the risk of premature death.
A recently published review found that people who exercised in polluted air had a 26 percent lower risk of death than people who did not exercise.
As expected, exercising in clean air was found to be better. This reduced the risk of death by 31 percent.
De Nazel says that this information is encouraging for the people living in cities.
However, in all circumstances the benefits of exercising outside do not outweigh the risks of air pollution. For this, it is important to keep your health and diseases in mind.
Who should be more careful?
People with pre-existing health problems like asthma or heart disease should take extra caution.
Other research has found that exercising even in polluted areas improves lung function and reduces blood pressure.
Exercise can also reduce some of the effects of pollution on thinking ability. But how polluted the air you are breathing makes an even bigger difference.
In the year 2018, Sinhare and his colleagues included some elderly people along with healthy people for a study. These elderly people had chronic lung disease COPD or coronary heart disease.
These people were asked to walk for two hours. Some people took a walk in the park and some along a busy London road.
Researchers found that after just two hours, people who walked in clean air had improved lung and blood vessel function.
People living in areas with high pollution got less benefit from it. In people with COPD, symptoms of the disease worsened after exposure to polluted air.
In other words, exercise reduces many of the harms caused by pollution. But the opposite is also true. Excess pollution reduces the protection the body gets from exercise.
It also reduces the benefits that exercise provides to thinking ability.
Therefore, in most cases, the benefits of exercise outweigh its risks. But exercising in polluted air is still not a good situation.
How to reduce exposure to polluted air
People living in busy cities cannot leave their homes and go to the village for running. But our next best option is to find the greenest or least crowded place nearby.
For example, I may cycle on a road with less traffic on my way to work in the morning. However, it takes a few minutes more to go that route.
De Nazel says research shows that moving just one or two streets away from a high-traffic road reduces exposure to pollution by 20 to 30 percent.
If you can go through small or internal lanes, it is even better. One study found that traveling through inner streets instead of busy roads reduced exposure to pollution by 50 percent.
If possible, it is also best to avoid going out during the peak traffic times in the morning and evening.
Kharais says that vehicles parked at one place in traffic create areas of pollution where its quantity is very high.
His advice is to pay attention to the increased amount of ozone during hot and sunny afternoons. She says that ozone starts forming near the ground in extreme heat and strong sunlight. If rush hour air pollution is also added to this, the problem increases further.
Must see air quality index
"This is a system-wide problem," she says. "Individual choices can reduce an individual's exposure to polluted air. But the most effective protection will come from curbing emissions from polluting sources."
I would prefer to go to a local park for my next race.
- Melissa Hogenboom is a senior health correspondent at the BBC. She is the author of the books 'Breadwinners' and 'The Motherhood Complex'. Her name on Instagram is (melissa_hogenboom).
- All the information given in this article is for general information only. These should not be considered a substitute for medical advice from health experts.
