India's air pollution is no longer a problem confined to a handful of particularly bad winter days. As temperatures fall, weather conditions increasingly favour pollutant buildup; in many North Indian cities, including Delhi and the surrounding National Capital Region (NCR), this means prolonged periods of unhealthy air. For millions of children, this also means spending much of the winter breathing air laden with fine particulate matter and other pollutants.
UNICEF's July 2026 report, Environmental Determinants of Respiratory Disease in Children, identifies air pollution as a major risk factor for childhood respiratory disease. It highlights transport emissions, household fuel burning, industrial pollution, waste burning, dust storms, and second-hand tobacco smoke as sources of harmful exposure.
Although daily pollution levels fluctuate with wind, temperature, rainfall and emissions, the winter pollution season is expected to remain a recurring challenge over the coming months in Delhi and in many North Indian regions.
For adults, the immediate experience is familiar: burning eyes, sore throats, coughing, headaches and breathlessness. But for children, experts say the concern is considerably greater. Their lungs, brains and immune systems are still developing, making childhood exposure to polluted air a public-health issue carrying implications that may extend well into adulthood.
Experts say children's vulnerability is one reason the issue cannot be treated as a seasonal inconvenience.
The question is not simply how many children develop a cough during winter, but what repeated exposure to polluted air over several years could mean for their growth, development and future health.
Why do winter months become a problem?
Low temperatures play an important role in worsening winter pollution across Delhi-NCR and the Indo-Gangetic Plain.
As the air near the ground becomes colder, the atmospheric boundary layer — the lower part of the atmosphere in which pollutants mix and disperse — tends to become shallower. This traps pollutants in a smaller volume of air near the surface. Cold winter nights also favour temperature inversion, when a layer of warmer air sits above colder air near the ground, acting like a lid and preventing polluted air from rising. Calm winds, fog and reduced atmospheric mixing further restrict dispersion.
The WHO guideline for annual average PM2.5 concentration is 5 micrograms per cubic metre. In Delhi, the annual average is much higher, often around 60-80 micrograms per cubic metre or more.
"An increase of 10 micrograms per cubic metre in PM2.5 concentration is roughly equivalent to smoking another cigarette a day, according to the commonly used pollution-to-cigarette comparison. During winter, when pollution levels become extremely high, the exposure can be equivalent to smoking eight to 10 cigarettes a day. When the AQI crosses 500, the equivalent exposure could be even higher,” says Dr Manish Taneja, a critical care medicine specialist at Ujala Cygnus in Haldwani and a doctor with a popular Instagram ID, @resuscitateindia.
"Even on what we consider a good day in Delhi, the PM2.5 concentration can be 60 or 70. That is already many times higher than the WHO guideline,” he says.
Why children are more vulnerable
Experts say we need to remember ‘children are not simply smaller versions of adults' and when it concerns air pollution, that distinction matters even more. Their bodies are still developing, and the way they breathe and relate to their environment makes them particularly vulnerable.
The State of Global Air 2024 report, produced by the Health Effects Institute (HEI) and the Institute for Health Metrics and Evaluation (IHME), in partnership with UNICEF, explains that children breathe more air than adults. They also tend to spend more time outdoors and often breathe through their mouths, increasing their exposure to pollutants.
"Children have developing lungs. We earlier 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 have suggested that lung development continues much longer, potentially into adolescence and early adulthood,” Dr Taneja.
Children also breathe much faster than adults. An adult generally takes around 10-20 breaths a minute, while children can take 30-40, or even 50, depending on their age.
"This means that children inhale a greater amount of polluted air compared to their body weight. They receive a higher dose of pollutants per kilogram of body weight than adults,” he adds.
Renowned paediatrician Dr Sivaranjani Santosh says PM2.5 particles are particularly dangerous because they are extremely small. They can travel deep into the lungs, reach the alveoli and enter the bloodstream, triggering inflammation.
"So we are not talking about a problem that affects only the lungs. Air pollution can affect the brain, heart, and several other organs. Children are particularly vulnerable because their lungs, brains and immune systems are still developing,” Dr Santosh says.
Recalling his experience living in Delhi with a young child, Dr Taneja described how pollution could keep his child indoors for extended periods. “This could not be his childhood,” he says, talking about his decision to leave Delhi some time ago.
According to the UNICEF report, 709,000 deaths among children under five globally in 2021 were associated with air pollution, second-largest risk factor for deaths in this age group after malnutrition.
What polluted air does to developing lungs
One of the most established health consequences of air pollution in children is damage to respiratory health.
A January 2024 study published in The Lancet Regional Health – Southeast Asia found a significant association between higher PM2.5 exposure and respiratory illness among young children.
Fine particulate matter, particularly PM2.5, is a major concern as it is small enough to penetrate deep into the lungs and reach the air sacs. Exposure can cause inflammation and oxidative stress, affecting the respiratory system.
“Children exposed to polluted air face a higher risk of respiratory infections, asthma symptoms, and impaired lung function. For those who already have asthma, pollution can trigger exacerbations, increase coughing and wheezing, allergic rhinitis and enlarged adenoids and make breathing more difficult,” says Dr Santosh.
“Pollution can aggravate existing airway inflammation and allergic conditions, making symptoms harder to control,” she adds.
Can pollution affect children's brains and learning?
The effects of air pollution may not stop at the lungs. An emerging area of research is examining how exposure to fine particulate matter affects the developing brain and children's cognitive abilities.
A review published in Developmental Cognitive Neuroscience in October 2024 examined 40 studies and found evidence linking air pollution to brain functioning and development, raising concerns about effects throughout critical stages of neurodevelopment.
Another study, published in Environmental Health in November 2024, found a significant association between higher PM2.5 exposure and lower overall, verbal, and performance IQ scores.
These conclusions add to concerns about possible effects on attention, memory, learning and neurodevelopment.
Neurologist Dr Sudhir Kumar of Apollo Hospitals, Hyderabad, says air pollution is also recognised as a risk factor for neurological and heart-related conditions, including stroke and hypertension. “ We traditionally talk about diabetes, hypertension and cholesterol when discussing stroke risk. However, research published in major journals, including The Lancet, has pointed out the growing contribution of environmental factors such as air pollution.
There is evidence linking exposure to air pollution with an increased risk of stroke. Pollution is also associated with a higher risk of developing hypertension,” says Dr Kumar.
Dr Sudhir Kumar explains that inhaled pollutants can trigger inflammation and damage the endothelium, the thin inner lining of blood vessels. “Such damage can encourage the accumulation of platelets and other substances, contribute to narrowing of blood vessels, and increase the risk of clot formation. These processes are relevant to cardiovascular events and stroke,” he said.
Long-term exposure to PM2.5 can contribute to systemic inflammation. For children, repeated exposure during critical developmental years could affect respiratory and cardiovascular health over time.
The damage may begin before birth.
A child's exposure to polluted air can begin in the womb.
The UNICEF report also points out that pollution exposure can begin before birth. Some pollutants can cross the placenta, exposing the developing foetus. Exposure during pregnancy has been associated with low birth weight and premature delivery, conditions that can increase a newborn's vulnerability to respiratory infections and other complications.
Research cited in the State of Global Air 2024 report also links maternal exposure to air pollution with premature birth and low birth weight. Pollutants can contribute to inflammation and oxidative stress in the mother's body and may affect the placenta and the developing foetus.
The report also highlights newborns' vulnerability, particularly during the first month of life.
"We tell pregnant women not to smoke for a reason. Many of the harmful effects associated with smoking can also be seen with exposure to polluted air. Like smoking, air pollution has been linked to low birth weight, miscarriages and adverse pregnancy outcomes,” Dr Taneja.
Protecting children requires more than seasonal restrictions.
Delhi's recurring air pollution crisis cannot be solved by asking children to remain indoors for several months every year.
UNICEF's July 2026 report calls for comprehensive policies. It recommends enforcing air quality standards, reducing exposure to second-hand smoke, ensuring access to clean household fuels, improving green spaces and strengthening preparedness in schools and childcare centres.
For Delhi-NCR, this means addressing multiple sources of pollution, including vehicular emissions, construction and road dust, industrial pollution, waste burning and regional sources. Schools, hospitals and childcare facilities also need plans to protect children during pollution episodes.
“Around 2013, Beijing faced air quality levels similar to Delhi's. But over the next decade, it went down from an average PM2.5 concentration of around 80 micrograms per cubic meter to 20 in 2025. This shows that the problem can be addressed, but it needs sustained effort,” says Dr Taneja.