Association of FEV1 in Asthmatic Children with Personal and Microenvironmental Exposure to Airborne Particulate Matter Ralph J. Delfino,1 Penelope J.E. Quintana,2 Josh Floro,1 Victor M. Gastañaga,1 Behzad S. Samimi,2 Michael T. Kleinman,3 L.-J. Sally Liu,4 Charles Bufalino,1 Chang-Fu Wu,4 and Christine E. McLaren1 1Epidemiology Division, Department of Medicine, College of Medicine, University of California at Irvine, Irvine, California, USA; 2Division of Occupational and Environmental Health, Graduate School of Public Health, San Diego State University, San Diego, California, USA; 3Department of Community and Environmental Medicine, College of Medicine, University of California at Irvine, Irvine, California, USA; 4Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington, USA Abstract Exposure to particulate matter (PM) air pollution has been shown to exacerbate children's asthma, but the exposure sources and temporal characteristics are still under study. Children's exposure to PM is likely to involve both combustion-related ambient PM and PM related to a child's activity in various indoor and outdoor microenvironments. Among 19 children with asthma, 9-17 years of age, we examined the relationship of temporal changes in percent predicted forced expiratory volume in 1 sec (FEV1) to personal continuous PM exposure and to 24-hr average gravimetric PM mass measured at home and central sites. Subjects were followed for 2 weeks during either the fall of 1999 or the spring of 2000, in a southern California region affected by transported air pollution. FEV1 was measured by subjects in the morning, afternoon, and evening. Exposure measurements included continuous PM using a passive nephelometer carried by subjects ; indoor, outdoor home, and central-site 24-hr gravimetric PM2.5 (PM of aerodynamic diameter < 2.5 µm) and PM10 ; and central-site hourly PM10, nitrogen dioxide, and ozone. Data were analyzed with linear mixed models controlling for within-subject autocorrelation, FEV1 maneuver time, and exposure period. We found inverse associations of FEV1 with increasing PM exposure during the 24 hr before the FEV1 maneuver and with increasing multiday PM averages. Deficits in percent predicted FEV1 (95% confidence interval) for given PM interquartile ranges measured during the preceding 24-hr were as follows: 128 µg/m3 1-hr maximum personal PM, -6.0% (-10.5 to -1.4) ; 30 µg/m3 24-hr average personal PM, -5.9% (-10.8 to -1.0) ; 6.7 µg/m3 indoor home PM2.5, -1.6% (-2.8 to -0.4) ; 16 µg/m3 indoor home PM10, -2.1% (-3.7 to -0.4) ; 7.1 µg/m3 outdoor home PM2.5, -1.1% (-2.4 to 0.1) ; and 7.5 µg/m3 central-site PM2.5, -0.7% (-1.9 to 0.4) . Stronger associations were found for multiday moving averages of PM for both personal and stationary-site PM. Stronger associations with personal PM were found in boys allergic to indoor allergens. FEV1 was weakly associated with NO2 but not with O3. Results suggest mixed respiratory effects of PM in asthmatic children from both ambient background exposures and personal exposures in various microenvironments. Key words: asthma, epidemiology, forced expiratory volume, longitudinal data analysis, nitrogen dioxide, ozone, panel study, particulate air pollution. Environ Health Perspect 112:932-941 (2004) . doi:10.1289/ehp.6815 available via http://dx.doi.org/ [Online 4 March 2004] Address correspondence to R.J. Delfino, Epidemiology Division, Department of Medicine, College of Medicine, 224 Irvine Hall, University of California Irvine, Irvine, CA 92697-7550 USA. Telephone: (949) 824-1767. Fax: (949) 824-1343. E-mail: rdelfino@uci.edu We thank the staff at the San Diego Air Pollution Control District for providing stationary-site data for air pollutant gases and weather and for their assistance in placement of our air monitors. The project described was supported by grant ES06214 from the National Institute of Environmental Health Sciences (NIEHS) , and its contents are solely the responsibility of the author and do not necessarily represent the official views of the NIEHS. The authors declare they have no competing financial interests. Received 24 October 2003 ; accepted 4 March 2004. The full version of this article is available for free in HTML or PDF formats. |