Project at a Glance

Title: Relationship between air quality and the respiratory status of asthmatics in an area of high oxidant pollution in Los Angeles County

Principal Investigator / Author(s): Gong, Henry Jr.

Contractor: UCLA Schools of Medicine and Public Health

Contract Number: a1-151-33 & a4-135-33

Research Program Area: Health & Exposure

Topic Areas: Health Effects of Air Pollution, Vulnerable Populations


Relationship Between Oxidant Air Pollution and the Respiratory Status of Asthmatics in an Area of High Oxidant Pollution in Los Angeles County. H. Gong, Jr., M.S., Simmons, V.A. Clark, D. P. Tashkin, A. H. Coulson and G. H. Spivey.
A 230-day study of 83 asthmatics residing in an area of high oxidant air pollution was performed to evaluate: 1) the potential effects of ambient ozone on daily respiratory symptoms, medication use and peak expiratory flow rates and 2) the characteristics ozone-sensitive subjects. After completing a detailed Questionnaire and pulmonary function and psychological tests, each subject kept a daily record of symptoms, medication use, and peak expiratory flow rates (PEFR). The subject consisted of 43 males and 40 females with an average age of 33 years (range 7-70) and mild to severe asthma treated with inhaled bronchodilators and other anti-asthma medications. A Nebulizer Chronolog was attached to each canister of inhaled bronchodilators to objectively monitor its use and to make possible comparisons with diary reports. Daily maximum hourly average ozone concentrations in the study area were less than 0.12 parts per million (ppm) for 102 days, 0.12-0.19 ppm (National Primary Standard) for 65 days, 0.20-0.34 ppm (first-stage alert) for 60 days, and 0.35-0.38 ppm (second stage alert) for 3 days. Data were analyzed by several statistical methods, including multiple linear regression for each subject across time. Resulting regression coefficients were weighted inversely to their variance and averaged over subjects to derive an overall relation between ozone and the dependent variables. Analyses showed no significant overall effect of ozone on group respiratory status. However, consistent and statistically significant relationships were found in a subset of 63 subjects (75.9%). Two subgroups of "extreme" and "moderate" responders to ozone (based on their regression coefficients for ozone) were identified but they were neither statistically nor clinically different from the other subjects except in several categories of the Asthma Symptom Checklist. The responses in symptom scores, day PEFR and night PEFR, as predicted by slope coefficients for ozone, were clinically significant for eight subjects (9.6%) during the study, according to operational criteria. We conclude that the ambient ozone concentrations present during the study were associated with statistically significant changes in the respiratory status of the majority of asthmatic subjects. Although only a small subset of subjects had clinically significant responses to ozone, we speculate that more individuals could have had clinically relevant effects if their asthma and the oxidant air pollution were more severe than present in this study.

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