Delhi’s air pollution is often discussed in terms of AQI numbers and emergency measures. But what happens when toxic air becomes a daily health hazard, particularly for children? In this interview, Dr Manish Taneja, a critical care specialist, explains how prolonged exposure to air pollution affects the developing lungs and brains of children, why winter conditions make pollution more dangerous, and what the growing body of research tells us about its long-term health consequences. He also examines whether staying indoors, wearing masks and using air purifiers can meaningfully reduce exposure, and what parents can do to protect their children.
Excerpts from a podcast
How serious is the level of air pollution in Delhi? Can we understand its health impact by comparing it to cigarette smoking?
One commonly used comparison estimates that breathing Delhi's polluted air can be equivalent to smoking several cigarettes a day. At an annual average PM2.5 concentration of around 60–80 micrograms per cubic metre, the exposure is roughly comparable to smoking four cigarettes daily. During winter, when pollution levels become extremely high, the equivalent exposure may rise to eight to 10 cigarettes a day or more.
The World Health Organization's guideline for annual average PM2.5 is 5 micrograms per cubic metre. Even on what we consider a relatively good day in Delhi, PM2.5 levels can be around 60–70 micrograms per cubic metre — many times higher than the WHO guideline.
Why are children more vulnerable to air pollution than adults?
Paediatrics has a saying: children should not be treated as miniature adults. This is particularly relevant when discussing air pollution.
Children's lungs are still developing. We once believed that the number of alveoli, or tiny air sacs in the lungs, became fixed by around three years of age. However, advanced imaging studies suggest that lung development continues much longer, potentially into adolescence and early adulthood.
Children also breathe much faster than adults. While adults generally take 10–20 breaths a minute, children may take 30–50, depending on their age. They therefore inhale more polluted air relative to their body weight and receive a higher dose of pollutants per kilogram.
PM2.5 particles are particularly dangerous because they are extremely small. They can travel deep into the lungs, reach the alveoli and trigger inflammation. Some ultrafine particles may travel beyond the lungs. Studies have detected particulate matter in the bloodstream and even in the brain.
This is not simply a respiratory problem. Air pollution can affect the brain, heart and other organs. Children are especially vulnerable because their lungs, brains and immune systems are still developing.
What does research tell us about the impact of air pollution on children's brain development?
There is evidence suggesting that air pollution can affect cognitive development. A study from Barcelona found that children attending schools in areas with higher air pollution had poorer working memory than those studying in areas with lower pollution.
The pollution levels in those parts of Barcelona are still considerably lower than what children in Delhi are exposed to. We do not fully understand what prolonged exposure to such high levels of pollution may be doing to a child's developing brain.
Air pollution is also associated with inflammation in the body. Studies have found higher levels of inflammatory markers, including interleukin-6, among people exposed to polluted air. The effects are therefore not limited to respiratory symptoms. We need to consider the long-term consequences for the entire body.
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Is air pollution contributing to the rising burden of asthma among children?
Air pollution is associated with childhood asthma and can also worsen existing asthma.
During winter, temperature inversion traps pollutants closer to the ground. This is one reason pollution becomes particularly severe across North India.
Sulphur dioxide can undergo chemical reactions in the atmosphere and contribute to the formation of fine particulate matter. These particles are associated with asthma and its exacerbation. PM10 particles, although larger than PM2.5, can also irritate the airways. Since asthma is an airway disease, this irritation can trigger or worsen attacks.
Can air pollution affect a child even before birth?
We advise pregnant women not to smoke because of the risks to the developing baby. When discussing air pollution, we need to understand that exposure to polluted air can also have serious consequences.
Air pollution has been linked to low birth weight, miscarriages and adverse pregnancy outcomes. Studies have detected particulate matter on the foetal side of the placenta. This tells us that the placenta is not an absolute protective barrier against pollution. Harmful particles can cross this barrier and potentially affect the developing baby.
Are children the most overlooked victims of air pollution?
There is an inequality angle to air pollution that is not discussed enough. Adults may, in some ways, contribute to pollution through activities such as driving vehicles or burning coal. Children have done none of these things. They are not driving vehicles, burning coal or participating in construction activities.
Yet they are among the most vulnerable people exposed to polluted air. The most innocent people are often the ones who suffer the most. That is the inequality associated with air pollution that we need to talk about.
How can parents reduce children's exposure to pollution at home?
If you live in a polluted city and cannot move elsewhere, the first priority should be to reduce exposure as much as possible.
A study in Shanghai found that running HEPA-filter air purifiers indoors reduced PM2.5 levels by around 50 per cent and also reported a reduction in inflammatory markers.
Air purifiers need to be used properly. If your family spends most of its time in the living room, keep the purifier running there. If you are moving into a bedroom, ideally switch on the purifier two to four hours beforehand. Keep doors and windows closed as much as possible during periods of high pollution. If you can afford it, invest in good air purifiers for the rooms where your family spends most of its time.
Should children wear N95 masks when they go outdoors?
Well-fitting N95 masks work well for adults who need to go outside. However, masks can be a problem for children because adult-sized masks may not fit them properly.
Mask use is also not recommended for children below two years of age because of the risk of suffocation and other safety concerns. For younger children, exposure needs to be reduced through other measures, particularly by limiting the time they spend outdoors when pollution levels are high.
Is there a safer time of day for children to go outdoors?
Delhi's pollution levels are not the same throughout the day. During early mornings and late evenings, when the air is colder, pollutants tend to remain closer to the ground because of atmospheric inversion. During warmer parts of the day, the inversion effect may weaken, allowing some pollutants to disperse.
If children have to go outside, it may be better to choose a relatively warmer part of the day. Parents should also avoid taking them out along busy roads. Much of Delhi's pollution comes from vehicular emissions, and children can be exposed to exhaust close to the road.
Travelling by car rather than walking along heavily polluted roads may reduce exposure. A car with a good cabin air-filtration system can offer relatively better protection, although it cannot eliminate exposure.
Should people stop exercising outdoors during periods of severe pollution?
I am not suggesting that people stop exercising. I am saying they should exercise indoors during periods of severe pollution.
Exercise is important for cardiovascular health, lung health and overall well-being. Aerobic exercise, brisk walking and resistance training are all beneficial. But when you exercise outdoors, you breathe faster and often through your mouth. This means you inhale more polluted air, while bypassing some of the nose's natural filtering mechanism.
In a moderately polluted environment, outdoor exercise may still be possible. But Delhi's winter pollution levels can be extremely high, and I would not recommend exercising outdoors during those periods.
Children should also be allowed to play. We cannot keep them cooped up throughout their childhood. Parents should try to limit their exposure, encourage indoor play and allow shorter periods of outdoor activity when conditions are relatively better.
What can India learn from Beijing's experience in tackling air pollution?
Beijing was facing air pollution levels similar to Delhi around 2013. Over the following decade, it managed to bring its average PM2.5 concentration down from around 80 micrograms per cubic metre to approximately 20 in 2025.
This shows that the problem can be addressed, but it requires sustained political commitment. One of the biggest problems is that we often try to hide the problem instead of openly acknowledging it and explaining how we plan to solve it.
For instance, people were celebrating that Delhi had experienced its best October in several years. But that happened largely because of rainfall. We cannot depend on rain to solve air pollution. It will not rain every time. We need to accept the data and acknowledge the scale of the problem before we can start addressing it.
What is your advice to parents living in highly polluted cities?
My advice is simple: reduce exposure as much as possible. Keep children indoors when pollution levels are extremely high and use HEPA-filter air purifiers. When going outside, adults should wear well-fitting N95 masks. Try to plan outdoor activities during warmer parts of the day, when pollution levels may be relatively lower.
Do not give up exercise altogether; move it indoors during severe pollution episodes. And please do not fall for products claiming that gummies, vitamins or supplements can protect children from pollution. There is no shortcut.
Instead of spending money on products that promise to protect the lungs, invest in a good air purifier. Check its Clean Air Delivery Rate (CADR) and make sure it is appropriate for the room size.