California Air Resources Board

This study is an epidemiological study of the acute respiratory health effects of air pollution, particularly air toxics, on children with asthma. Twenty-six asthmatic Hispanic school children residing in Eastern Los Angeles participated in the study during the winter of 1999-2000. The study was co-sponsored by the California Air Resources Board and the South Coast Air Quality Management District and conducted by investigators at the University of California, Irvine.

Study Importance

• The information gathered in this study provides insight regarding the measurement methods needed to assess personal Volatile Organic Compound (VOC) exposures and doses in children.
• The association between exposure to VOCs and asthma symptoms is largely unknown. This is one of the first epidemiological studies to evaluate the association between exposure to VOCs and other criteria air pollutants and acute health effects in asthmatic children.

Study Location

This study took place in the Huntington Park region of Eastern Los Angeles. The investigators made use of two outdoor air toxics monitors operated by the South Coast Air Quality Management District (highlighted in yellow).

Information Gathered 

This study consisted of a variety of measurements taken daily over the course of about two months. All subjects recorded daily health outcomes (whether or not they had an asthma episode), where and how much time they spent in different locations (for example, time spent in the car on the way to school) and peak expiratory flow of the lungs. VOC exposure was measured using breath samples and personal, indoor home and outdoor stationary site VOC samplers. VOCs measured included: 1,1-dichloroethane, benzene, carbon tetrachloride, chloroform, styrene, tetrachloroethylene, toluene, m, p-xylene, o-dichlorobenzene, o-xylene and p-dichlorobenzene.

Important Findings

• Ambient VOCs (benzene, ethylbenzene, tetrachloroethylene and m,p-xylene) showed associations with symptoms.
• Criteria pollutants, including ambient ozone, nitrogen dioxide, sulfur dioxide and particulate matter (PM10) showed significant associations with asthma symptoms.
• Organic carbon and elemental carbon also showed significant associations with symptoms.
• An association was seen between bothersome asthma symptoms and both breath and ambient concentrations of benzene.
• Personal exposures and indoor concentrations were correlated for most VOCs.
• Breath VOC concentrations did not correlate with outdoor VOC concentrations (except for benzene and m,p-xylene).

Final Report

The final report from this study is available. In addition to the final report, two peer review articles have been published on the study:

1. Delfino RJ, et al. Asthma symptoms in Hispanic children and daily ambient exposures to toxic and criteria air pollutants. Environmental Health Perspectives 111:647-656 (2003)
2. Delfino RJ, et al. Respiratory symptoms and peak expiatory flow in children with asthma in relation to volatile organic compounds in exhaled breath and ambient air. Journal of Exposure Analysis and Environmental Epidemiology 13:348-363 (2003).