In London, children’s lungs grow faster as traffic pollution falls

Cutting traffic pollution is linked to faster lung growth in children, according to a new study conducted in London.

To reduce the health effects of air pollution, many cities have introduced so-called Ultra Low Emission Zones (ULEZs). These schemes restrict or charge drivers of more polluting vehicles to encourage cleaner transport.

A study published in The Lancet Public Health suggests that reducing traffic pollution can benefit children’s lung health.

Scientists from Queen Mary University of London followed more than 3,400 children aged 6 to 9.

The introduction of the ULEZ provided a “natural experiment”, allowing them to compare children in central London with a similar group in Luton, where there was no clean-air zone.

Each year, the researchers used a breathing test to measure how much air the children could forcefully exhale in one second, a standard measure of lung function.

Before the ULEZ was introduced, children in London had slower lung growth, the researchers found. But within five years, this began to change.

Pollution fell more than twice as fast in London

Pollution levels fell in both Central London and Luton, but the reduction was more than twice as large in Central London. Levels of nitrogen dioxide, a pollutant closely linked to vehicle exhaust, fell by about 3.8 micrograms per cubic metre per year in London, compared with 1.8 in Luton.

As pollution levels fell, the London children’s lungs began to grow faster. Their lung function grew by an average of 233 millilitres per year, compared with 223 millilitres in Luton.

After four years, the difference between the two groups had disappeared: the children in London had caught up with those in Luton.

The researchers say theirs is the first study to show that improving air quality through a clean-air zone is associated with faster lung growth in children.

The findings could have important health implications. Children whose lungs do not fully develop are at greater risk of asthma and other health problems later in life. In Central London, the proportion of children with impaired lung function fell from 14% to 9% as pollution levels dropped.

ULEZ introduction has been controversial

The ULEZ has nevertheless been controversial, with a number of its cameras vandalised or stolen, according to the Metropolitan Police.

The zone was extended from central London to inner London in October 2021, and across all of London’s boroughs in August 2023.

The 2023 expansion was challenged in court by several London councils, but the High Court ruled that it could go ahead.