Air pollution is bad for people's health, but would it really make much of a difference if the air started to get cleaner? Well it did in Southern California. When air pollution dropped, so did childhood asthma.
Asthma is the most common chronic children's disease, affecting about 14% of children worldwide.
The drop in nitrogen dioxide that occurred between 1993 and 2006 led to a 20 percent lower rate of new asthma cases, while the drop in fine particulate matter led to a 19 percent lower rate.
Los Angeles and its surrounding areas have some of the country's dirtiest air, but with the help of emissions regulations it has been getting cleaner. Between 1993 and 2006, nitrogen dioxide levels in the Los Angeles area dropped by 22 percent. Fine particulate matter (PM2.5) dropped by 36 percent.
Levels of four different air pollutants in nine Southern California communities located near Los Angeles were taken in three different years, and then compared to the number of new asthma cases occurring in schoolchildren, starting in 1993. The nine communities studied were: Alpine, Lake Elsinore, Lake Gregory, Long Beach, Mira Loma, Riverside, San Dimas, Santa Maria and Upland. They are, on average, 60-70 miles from Los Angeles.
Two pollutants, nitrogen dioxide and fine particles (PM2.5) — mainly soot, smoke and dust — showed a significant correlation with new asthma cases did, while two other pollutants, ozone and PM10 (particles smaller than 10 micrometers), did not show a strong relationship with asthma cases.
The researchers estimate that the drop in nitrogen dioxide that occurred between 1993 and 2006 led to a 20 percent lower rate of new asthma cases, while the drop in fine particulate matter led to a 19 percent lower rate.
Communities that had larger drops in either nitrogen dioxide or PM2.5 had even greater declines in new asthma cases.
The study makes clear that there are major health benefits to be gained by cleaning up the air. Benefits and healthcare savings that over time will far outweigh the costs of pollution control. As an editorial accompanying the study puts it, “This study also adds to the urgency of controlling ambient air pollution to benefit the next generation, and makes recent efforts to discredit and ignore evidence on health effects of ambient pollution even more concerning.”
Both the study and editorial appear in JAMA.