Concepts in developing health-based indicators for ozone.
OBJECTIVES: The traditional manner to evaluate whether regulatory controls meet their public health goals of reducing adverse health effects associated with exposure to environmental pollutants is to compare measured concentrations of the target pollutant in the environment with a standard. A complementary approach is also to measure health-based indicators, e.g., changes in the prevalence of adverse health outcomes attributed to the pollutant. This manuscript presents the concepts of using asthma emergency room (ER) visits and hospital admission as potential health-based indicators for ozone. METHODS: The frequency of ER visits and hospital admissions for asthma in New Jersey in 1995 was compared with daily ozone concentrations, to establish the consistency of the relationship and the presence of potential confounders, and to establish whether routinely documented adverse outcomes in asthmatics could serve as health-based indicators. RESULTS: A mathematical model relating ER visits and hospital admissions of asthmatics to ozone concentration was developed for 1995, which was to be used as a baseline year within a health-based indicator program. A coherent relationship was found between same-day ambient air ozone concentrations and ER visits and 2-day time-lagged ambient ozone and hospital admissions during 1995; pollen was identified as a confounder and the association between ER visits and ozone concentration was similar to that determined for 1986 to 1990. CONCLUSIONS: Sufficient databases exist for ER visits by asthmatics in Northern and Central New Jersey, and throughout the state for hospital admissions, for these health outcomes to be used as health-based indicators, complementing air-monitoring data in assessing whether improvements in public health are occurring because of reduction in emissions of precursors of ozone.