The air we breathe might not only have a serious impact on our own health, but also that of a generation that is yet to be born. A recent study has shown that pregnant women who are exposed to heavy air pollution may be at a greater risk of giving birth to underweight babies.

The research was carried out in London, which suffers from worryingly high levels of air pollution, and assessed more than half a million infants born between 2006 and 2010. This was then paired with data on emissions of nitrogen dioxide, nitrogen oxides, fine particulate matter, and large particulate matter, as well as day and night road traffic noise levels.

They found that while there was no observable effect from exposure to noise pollution, when it came to air pollution – and especially small particulates – there was an increase in the chance that a baby will be born underweight by between 2 and 6 percent. There was also a 1 to 3 percent increase in odds that babies will be small for their gestational age.

“Our study has shown that a small but significant proportion of babies born underweight in London are directly attributable to exposure to air pollution, particularly to small particles produced by road traffic,” says Dr Mireille Toledano, who led the research published in the British Medical Journal, in a statement.

It is expected that the results gathered in the UK will be applicable to many other large cities throughout Europe. On average, the women were breathing in levels of air pollution higher than the World Health Organization limits, with the researchers finding that if the UK managed to stick to this recommendation, it could prevent up to 350 babies being born underweight each year.

At the same time as this research was released, the United Nations Children's Fund (UNICEF) also published a report on the effects of air pollution on young children around the world, specifically highlighting how 17 million babies worldwide are growing up breathing air six times more toxic than the WHO recommendations.

“Young children’s immune systems are still developing, and their lungs are still growing,” writes Unicef. “With every breath, children take in more air per unit of body weight than adults. By extension, when air is toxic, they take in more toxic air per unit of body weight than adults.”

The impacts on children don’t stop at how the pollution directly affects their health. If a child becomes sick, then they have to take time off school. This in turn has a knock-on effect on their education and cognitive development, exasperating existing problems and further limiting their potential.