About 17 million babies worldwide live in areas where outdoor air pollution is six times the recommended limit, and their brain development is at risk, the United Nations children's agency (UNICEF) said on Wednesday.
Babies in South Asia were worst affected, with more than 12 million living in areas with pollution six times higher than safe levels.
"As more and more of the world urbanises, and without adequate protection and pollution reduction measures, more children will be at risk in the years to come".
Air pollution for long has been known to cause several ailments related to breathing and general health and according to the United Nations Children's Fund report titled "Danger In the Air" air pollution can also permanently damage a child's brain.
According to the American Lung Association's "State of the Air" report for 2017, almost 40 percent of the United States' population still lives in counties that have unhealthful levels of air pollution.
Lake called on countries exceeding worldwide limits to step up efforts to reduce air pollution.
Babies are also more susceptible to the effects of air pollution because they breathe more rapidly and their immune defenses are not fully developed.
It also urged public authorities to invest in cleaner, renewable energy, and to make it feasible for children to travel at times of day when pollution is lower, as well as to make sure major sources of pollution are not located near schools, clinics or hospitals.
The report said further research was needed to study the full impact of air pollution on children's developing brains.
UNICEF researchers add that the first 1,000 days of a child's life are critical to their long-term development and must be protected from hazards that threaten their physical and mental health.
It called for a greater use of masks, air filtration systems and for children to avoid travelling when pollution levels are at their highest.