Thus, it is not only the lungs which are most prone to the dangers of toxins and harmful pollutants the child's brain is equally affected.
The report comes at a time when north India, particularly Delhi and adjoining areas, battle high pollution levels with air quality swaying from "very poor" to "emergency" levels, restricting physical activity and forcing closure of schools.
Air pollution has already been linked to asthma, bronchitis, and other long-term respiratory diseases.
"But a growing body of scientific research shows a new potential risk posed by air pollution to the lives and futures of children: its impact on their developing brains", now says Unicef.
Nearly 17 million babies live in areas where air pollution is at least six times higher than global limits, causing them to breathe toxic air and potentially risking their brain development, according to a new paper released on Tuesday by the United Nations Children's Fund (UNICEF).
The pollution " will impact the learning of the children, their memories, their language skills and motor", said to AFP Nicholas Rees, author of the report. More than three-quarters of these young children - 12 million - live in South Asia.
Pollutants inhaled by pregnant women may pass through the placenta and disturb the development of the brain of the foetus.
One study reports a four-point drop in IQ by the age of 5 among a sample of children exposed in utero to toxic air pollution, it said.
The report recommends wider use of filter masks in developing countries and for children to not be allowed to travel outside during spikes in pollution.
The World Health Organization describes air pollution as a "major environmental risk to health".
Even as the National Capital and adjoining regions are grappling smog and air pollution for over a month now, the issue has been raised at the highest worldwide level as United Nations global Children's Emergency Fund (UNICEF) has taken a serious view of the situation.
According to the American Lung Association's "State of the Air" report for 2017, almost 40 percent of the United States' population still live in counties that have unhealthful levels of air pollution.