Improved air quality linked to better mental development in toddlers, study finds

Improvements in air pollution are leading to brighter, smarter toddlers, according to a new study from Columbia University in New York.

For more than two decades, Prof Frederica Perera and a team from the Columbia Center for Children’s Environmental Health measured the air pollution exposure of pregnant women and the development of their children in the disadvantaged communities of northern Manhattan and the South Bronx. More than 1,100 children were assessed when they were one, two and three years old.

Perera said: “We tested cognitive processing including memory and sensory perception, problem-solving such as matching shapes, stacking blocks and communication, both speech and language comprehension. In the early years of the study, we reported significant associations between prenatal exposure to air pollution and neurodevelopment effects in the children. That was bad news.”

Over the course of the study, air pollution in central New York improved massively. Clean-air legislation reduced some pollutants from the city’s yellow taxis by as much as 80%. Heavy fuel oils are being phased out for heating the city’s buildings and cleaner fuels are being used in the city’s buses. Fine particle pollution and levels of nitrogen dioxide halved between 1998 and 2016.

Perera continued: “Would we see an association between improved air quality and improved mental development scores in the toddlers over time?”

The good news is that the toddlers’ scores improved as the air pollution improved. This was especially clear when the children were two and three years old, and during times of sharper falls in air pollution. The researchers were also able to take into account the effects of other factors that may have affected the children’s development. These included rapid declines in the proportion of children who lived with a tobacco smoker, which fell from 34% to 18%, and increases in maternal education, with a nine percentage-point increase in the proportion of mothers who had successfully graduated from high school.

The New York study adds to the growing evidence that air pollution is a fixable problem and that health improves when air pollution is reduced.

In the UK, the introduction of London’s ultra-low emission zone was accompanied by an improvement in children’s lung health and fewer children with clinically impaired lung function. For adults in central London, there was a 3% reduction in annual trends for emergency admissions, including an 8% reduction for heart problems and a 6% reduction for breathing problems. A reduction of about 25% in GP visits for heart and breathing problems followed the implementation of a clean-air zone in Bradford, West Yorkshire.

Despite the improvements in New York, Perera emphasised: “We cannot conclude that contemporary levels of air pollution are safe for the neurodevelopment of all children.”

Action on air pollution requires bold political leadership. It is often controversial and can be made into a divisive political issue, but it can work. Perera said: “We need more studies such as ours to increase public awareness of the value of clean air and climate policies and motivate policymakers.”

A recent report by the UN Environment programme found that integrated action on air pollution and climate change emissions makes economic sense too, with an average return of $15 in economic benefits for every $1 invested.