Wildfires Linked to Increased Asthma Risk, with Women More Susceptible

2016 Wildfire photo courtesy of Kathleen Navarro.

Heightened exposure to fine particulate matter (PM2.5) during wildfire events is associated with a significant increase in asthma hospitalizations and emergency department (ED) visits, along with an increase in ED visits for chronic obstructive pulmonary disease (COPD). That is according to a new study by COEH researchers examining the health effects of a mega-fire event in Northern California that churned out a highly volatile smoke plume for six weeks in the summer of 2008 in an area populated by 17.2 million.

Colleen Reid

The investigation, led by UC Berkeley alumna Colleen Reid, PhD ’14, used a novel machine learning method that integrated intelligence from satellite retrieval systems, atmospheric chemistry models, and ground-based data to pinpoint at what level of PM2.5 the health effects began to rise during the event and what populations were most sensitive to heightened air pollution, a major step forward for public health agencies preparing for an increase in fire events due to climate change.

Previous studies of the effects of PM2.5 have traditionally relied on data from fixed monitoring stations that may impart measurement error, especially in the sparsely monitored air basins of the 2008 wildfire, which stretched across 781 ZIP codes from the Sacramento Valley to the North, through the San Francisco Bay Area and the North Central Coast, south to Big Sur and parts of the San Joaquin Valley.

This study estimated exposure to PM2.5 for each day in each ZIP code before, during, and after the fire with a statistical model employing prediction variables such as aerosol optical depth from satellites, atmospheric conditions from the Weather Research and Forecasting with Chemistry model, land-use, elevation, temperature from the National Climatic Data Center, and traffic counts, among others. Recorded data from 112 PM2.5 monitoring stations were used as the dependent variable. Researchers also obtained daily counts of hospital admission visits and ED visits for each ZIP code for asthma, heart disease, pneumonia, hypertension, and more.

Results showed a clear relationship between PM2.5 from wildfires and respiratory hospitalizations and ED visits, reported investigators. Women were more susceptible than men to heightened PM2.5 exposure. Their results also signaled that “income affected respiratory ED visits during the wildfires, with the highest effects observed in the ZIP codes with the lowest median income.” The exposure model used proved highly predictive of PM2.5 concentrations reported from government air monitoring stations throughout the study area.

After completing her Ph.D. in Environmental Health Sciences at UC Berkeley, Reid accepted a post-doctoral appointment with the Harvard T.H. Chan School of Public Health as a Robert Wood Johnson Foundation Health and Society Scholar. In 2016, she joined the faculty of the University of Colorado, Boulder, as an assistant professor of Geography.

Northern California COEH co-authors on the June 2016 paper published in the leading journal Environmental Research include Director John Balmes, professor Ira Tager, and Research Scientist Jennifer Mann. Co-author Michael Jerrett is director of the Southern California COEH and Maya Petersen is an associate professor with the UC Berkeley School of Public Health.

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