A new study has found a statistical association between improvements in air quality and lung function growth in children.

The research, published in the New England Journal of Medicine, measured lung function annually in 2,120 children in southern California, where air quality control policies have been gradually implemented over the past few years.

The researchers used linear regression models to examine the relationship between decreasing pollution levels and lung-function development between the ages of 11 and 15 using spirometry.