New research this week questions the connection between air pollution and asthma.
In 2011, a study by the San Joaquin Valley Air Pollution Control District established a link between asthma-related ER visits and levels of PM2.5, or fine particulate matter in valley air. But after a follow-up to that study, the Air District now reports that for a number of years, asthma-related ER visits increased even as PM2.5 levels dropped.
David Lighthall, health science advisor to the Air District, says the findings should not be interpreted as black and white.