Environmental Assessment and Risk Analysis Element

The goal of air pollution reduction strategies in NJ is not merely to achieve regulatory compliance, but also to protect the public health of its citizens. It is therefore important to evaluate progress in ozone reduction by examining the extent to which health effects associated with ozone are being reduced. Previous studies have established an association between atmospheric ozone concentrations and severe asthma symptoms (those resulting in emergency room (ER) visits or hospital admissions for asthma). Daily ER visit and hospital admissions data for asthma are compared to NJ maximum daily 8-hour ozone concentrations while also accounting for daily temperature, pollen, and spore data to determine the extent of association between ozone and asthma and to investigate possible trends in ozone-related asthma for the period 1995-1999. During this period no consistent trend is evident. In some years, ozone accounted for 1-10% of ER visits or hospital admissions for asthma. In some years, however, no significant association was observed. A statistical model incorporating data for all years during this period indicates a significant association between ER visits for asthma and the previous 24 hour maximum 8-hour ozone concentrations, and between hospital admissions for asthma, and previous 24, and 48 hour maximum 8-hour ozone concentrations. In both cases ozone accounted for about 1% of ER visits or hospital admissions for asthma. These data further suggest the existence of a threshold for severe asthma symptoms related to ozone in NJ in the range of 60-80 ppb. The upper end of this range is consistent with the current USEPA 8-hour ozone standard. These results suggest that, in general, current ozone levels in NJ are close to the threshold for detecting an association with severe asthma symptoms. Continued reductions in ozone levels can further reduce the remaining associations. Further prospective and retrospective analysis can clarify the nature of the ozone-asthma relationship in NJ and can help determine when ozone levels are sufficiently low to eliminate all detectable associations. Alan H. Stern, Dr.P.H.1 Clifford P. Weisel, Ph.D.2,3 Ronald Cody, Ed.D.2