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Your Environment. Your Health.

Fewer New Asthma Cases With Improved Air Quality

Frank Gilliland, M.D., Ph.D.
University of Southern California
P30ES007048, P01ES009581, R01ES021801, R01ES025786

Air quality improvements in the Los Angeles region is linked to roughly 20% fewer new asthma cases in children, according to an NIEHS-funded study. The authors say the study provides evidence of a robust and consistent association between nitrogen dioxide levels in the community and development of asthma in childhood.

Air quality improvements in Los Angeles cut nitrogen dioxide pollution by 22% and fine particulate matter (PM) by 36% between 1993 and 2006. To assess new-onset cases of asthma before, during, and after this period, scientists used data from 4,140 children in nine California communities between 1993 and 2014. They identified physician-diagnosed cases of asthma from annual questionnaires completed by parents or guardians and collected community-level air pollution data for nitrogen dioxide, PM2.5, PM10, and ozone.

Using statistical methods, they examined the four air pollutants separately and found that reductions in nitrogen dioxide and PM2.5 were associated with fewer new-onset asthma cases. They estimated that nitrogen dioxide reductions achieved in the Los Angeles region between 1993 and 2006 led to a 20% lower rate of asthma. The researchers also found that decreased community-level PM2.5 was linked to a 19% lower rate, but more research is needed to confirm this association.

Citation: Garcia E, Berhane KT, Islam T, McConnell R, Urman R, Chen Z, Gilliland FD. 2019. Association of changes in air quality with incident asthma in children in California, 1993-2014. JAMA 321(19):1906-1915.

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