How does breathing toxic air affect a child’s growth? An expert explains

Children breathe more air per kilogram of body weight than adults. So for the same outdoor level of pollution (AQI/PM2.5), their intake is higher. Their lung and immune defences are still maturing, making pollutant injury more likely.

What can exposure to air pollution do?

It can lead to oxidative stress and inflammation. Short-term spikes in PM2.5 are associated with higher circulating C-reactive protein and cytokines, indicating systemic inflammation that can affect lungs, vasculature, and brain. Various neurological injuries can also happen. In short, analysis of brain tissue from people residing in highly polluted areas shows pollution exposure can trigger brain inflammation, damage, and early changes similar to those seen in people with Alzheimer’s disease.

In both people and animals, long-term exposure to air pollution can damage the brain’s protective barrier, activate immune cells in the brain, and cause changes similar to Alzheimer’s disease. It can also harm the brain’s wiring in areas that control thinking and behaviour. These changes help explain why pollution can affect memory, learning, and mood.

Pollution can also lead to epigenetic changes. It can change how genes are turned on or off without changing the genes themselves. This can happen by altering chemical tags on DNA and related molecules that may affect how the body develops and functions.

How does air pollution impact a child’s brain, growth, and development?

Various studies have found that higher prenatal or postnatal exposure to nitrogen dioxide (NO₂) and early-life exposure to PM2.5 can lead to behavioural problems and lower adaptive functioning among children. Breathing polluted air in the last few months of pregnancy can also increase the chance of newborn death.

It also leads to various neurodevelopmental disorders. Several studies show that when pregnant women or young babies are exposed to higher levels of PM2.5, the risk of autism may go up. The baby is also more likely to be born underweight. On an average, every small rise in the pollution levels pushes the risk of autism among children by 7-15%.

Air pollution is also a major cause of illness and death, including under-5 mortality (probability of dying before reaching age of 5) among children, in India. A 2019 study found that in 2017, the average air pollution level (PM2.5) across India was much higher than both the national and World Health Organization safety limits. About three out of four Indians were breathing air that was deemed “unsafe”.

Pollution was worst in Delhi, followed by Uttar Pradesh, Bihar, and Haryana. The study estimated that around 1.24 million people died (about 1 in 8 deaths) in India due to conditions aggravated by air pollution, adding that if pollution were reduced to “safe” levels, people could live about 1.7 years longer, on an average.

What informed decisions must parents take to reduce the risk?

Track the AQI and activities of your children. In Delhi-like cities, AQI is lower in April–September, unlike during October–March. Parents should minimise their children’s outdoor activities, thus exposure, when the air quality is bad. They should prioritise clean indoor air by also reducing household pollution. Pregnant individuals should avoid exposure when the AQI is high.

However, physical activity is crucial. The goal is exposure management, not elimination of outdoor activities for children.

The role of the government is to strengthen enforcement of rules for cleaner air, and ensure targeted protection and real-time guidance for pregnant women and young children in high-pollution settings.