Delhi's Air Is Rewriting Children's Lung Health

In the winter, breathing Delhi air is just one everyday exposure that kids have to medicine without them realising – a medicine that's now being documented by hard clinical data, not just anecdote.

The level of exposure is measured by the Scale of Exposure

According to a national study, which looked at the data of more than 2.24 lakh children aged up to five years across the country, there was a strong association between the exposure to PM2.5 and respiratory illness with the median PM2.5 concentration in the country at 63.4 micrograms per cubic metre, which is far higher than India's national standard of 40.

Of particular concern, scientists determined that even low to moderate exposures, below the official "safe" limits, increase the risk of respiratory illness, meaning that exposure levels of any sort are likely to be hazardous for young children's developing lungs.

Delhi's Winters, By the Numbers

According to a report by Centre for Science and Environment (CSE) in March, 2025, Delhi's ambient PM2.5 concentration averaged 175 micrograms per cubic metre during the winter peak season, which is much higher than India's 24-hour standard of 40.

The five-year monitoring data from 2019 to 2023 published in Scientific Reports showed that on most days during the study period pollutant levels in Delhi had surpassed both national and WHO guidelines, with peak PM2.5 levels reaching as high as 750.5 micrograms per cubic metre.

What Doctors Are Seeing

There is a consistent seasonal variation in emergency admissions, as described by the clinicians. Doctors referred to in the reports on pollution in Delhi said that "during peak pollution months there is a rise in acute respiratory diseases such as bronchitis, wheezing and asthma attacks, which leads to increased ER visits and hospitalisations.

In a previous cohort study, children living in Delhi were compared to those living in rural areas in Uttarakhand and West Bengal, and the study found that nearly twice as many children in Delhi had respiratory issues (32.1 per cent) compared to those in the rural areas (18.2 per cent).

Long-Term Development Risks

Aside from acute symptoms, there are longer-term consequences to be feared, researchers warn. A 2025 cross-sectional study of children in Delhi and Dhaka, both of which had annual average PM2.5 concentrations around 90 micrograms per cubic metre (µg/m3), which is almost 20 times the WHO limit of 5 µg/m3 per year, found that early-life exposure to PM2.5 "can impair lung development, contribute to long-term respiratory and cardiovascular conditions, and increase the risk of chronic disease across the life course.

The same study revealed that Delhi's air quality situation was not only a public health emergency for children's physical health but also affecting their sleep, school attendance and emotional wellbeing.