Better air quality reduces respiratory symptoms among children in southern California

Improvements in air quality over the past 20 years in southern California, USA, were linked to statistically significant decreases in bronchitic symptoms in children with and without asthma, a longitudinal study published in JAMA has found.1

Southern California has historically reported high levels of ambient air pollution, but air quality has significantly improved since 1992 owing to a range of policies and strategies.

The study included three cohorts that were followed from 1993 to 2001, 1996 to 2004, and 2003 to 2012. The cohorts included a total of 4602 children from eight communities …