The air pollution is damaging the health of babies and infants in India, a team of researchers have found after studying more than 250,000 children aged under five in 640 districts across the States.

The international research team included researchers from the Harvard Center for Population and Development Studies and the University of Colorado in the USA and the Indian Institute of Technology in Delhi.

They found that fine particulate matter in air has contributed to infant mortality in India. They identified that unborn children were exposed to increased levels of particulate matter during the later stage of pregnancy. They used satellite data to estimate the concentrations of fine particles during the month of each child’s birth.

India is ranked third only to Bangladesh and Pakistan for worst air quality. PM 2.5 concentration in India is 5.2 times above the WHO annual air quality guideline.

The researchers said that fine inhalable particles permeate the lungs of pregnant women, causing oxidative stress and disrupted hormone levels which affect fetal growth. This results in babies with a low birthweight.

They found that babies with a low birthweight were more likely to die in the first year of life, and the mothers’ inhalation of fine particles increased mortality for infant girls more than boys.

Analyses showed that the children who died in their first year of life were less privileged than those who survived. They also experienced higher exposure to particulate matter than children who survived.

The researchers found that both groups of children were exposed to concentrations of fine particles that exceeded the permissible limit set by the World Health Organization.

The researchers say urgent plans need to be devised to curb air pollution and reduce infant mortality in India. Previous studies have shown an association between air pollution and infant mortality, but none of these studies focused on India, where infant mortality is still very high.

In yet another study, scientists discovered increased heat was linked to fast weight gain in babies, which increases the risk of obesity in later life. Higher temperatures were also linked to premature birth, which can have lifelong health effects, and to increased hospital admissions of young children.

Other studies found exposure to smoke from wildfires doubled the risk of a severe birth defects, while reduced fertility was linked to air pollution from fossil fuel burning, even at low levels. The studies, published in a special issue of the journal Paediatric and Perinatal Epidemiology, spanned the globe from the US to Denmark, Israel and Australia.