CARB Research Seminar

This page updated March 22, 2018

Benefits of High Efficiency Filtration to Children with Asthma

Photo of presenterDeborah H. Bennett, Ph.D.

Deborah H. Bennett, Ph.D., Department of Public Health Sciences, University of California, Davis

April 13, 2018
Cal EPA Headquarters, 1001 "I" Street, Sacramento, CA

Press Release
Research Project


One-hundred ninety-one asthmatic children 6-12 years old, from 172 households, located in regions with high outdoor pollution (in and around Fresno and Riverside, CA), were enrolled in a randomized, placebo-controlled, cross-over design trial to evaluate the effectiveness of high efficiency filtration in reducing indoor exposures and asthma symptoms. One-hundred forty-nine participants from 136 households completed the study. High–efficiency filters were installed, utilizing the central system in 43 households and stand-alone air cleaners in 148 households.

Results showed that indoor air quality was significantly improved with filtration, with a 48% reduction in the mean indoor PM0.2 concentrations, similar PM2.5 reductions, and smaller PM10 reductions (31%). Air quality improvements were greater with stand-alone air cleaners than central-system filtration. Keeping windows closed and compliance with utilizing the intervention improved results.

While there was no improvement in asthma reported as frequency of symptoms in the prior two weeks with air filtration, there was a significant decrease in resource utilization (clinic visits, ER visits, and hospitalizations) particularly for severe asthmatics. In addition, participants with air cleaners in their bedroom slept better if they also kept their bedroom door closed.

Speaker Biography

Deborah H. Bennett, Ph.D., is a Professor at the Department of Public Health Sciences, University of California, Davis. Dr. Bennett's research focuses on the fate, transport, and exposure of particulate matter and compounds in multi-scale applications, including direct consumer product use, and indoor and outdoor multimedia environments within the context of both environmental epidemiology and environmental risk assessment. She utilizes both modeling and measurement techniques, bridging the gap between these two lines of inquiry. Dr. Bennett is conducting an intervention study to determine if high filtration of indoor air improves air quality and subsequent systems in pediatric asthmatics. Research interests also include development of methods to assess exposures in autism epidemiology studies for compounds found in consumer products and exposures to particulate matter, endotoxins, and pesticides among farmworker populations. She also conducts exposure studies focusing on flame retardants, hazardous air pollutants, and perfluorinated compounds. This work on exposure has received support from the California Air Resources Board and describes the development of modeling tools for two potential modes of releases during the use of consumer products (i.e., direct release to the outdoor air and disposed down the drain) to evaluate the availability of low vapor pressure-volatile organic compounds (LVP-VOCs) that may contribute towards ozone formation from the use of consumer products. She received her Ph.D. in Mechanical Engineering from UC-Berkeley in 1999 and was an assistant professor at Harvard School of Public Health before joining the UCD faculty in 2005.

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