HEALTH-EFFECTS OF TROPOSPHERIC OZONE - REVIEW OF RECENT RESEARCH FINDINGS AND THEIR IMPLICATIONS TO AMBIENT AIR-QUALITY STANDARDS

The U.S. Environmental Protection Agency (EPA) Administrator proposed (on August 3, 1992) to retain the current National Ambient Air Quality Standard (NAAQS) for ozone (O3) On the basis of data assembled in a d raft Criteria Document (1986) and its Addendum (1988) which, together with a draft Staff Paper (1988), received public comment and review co mments by the EPA's Clean Air Scientific Advisory Committee (CASAC). T his paper summarizes and discusses research findings presented since 1 988 which, based on the author's experience as a Chairman of CASAC, ar e most relevant to the promulgation of a primary (health based) NAAQS for O3. These newer findings include substantial evidence from control led chamber exposure studies and field studies in natural settings tha t the current NAAQS contains no margin of safety against short-term ef fects thal the EPA has considered lo be adverse. They also include evi dence from epidemiologic studies thal current ambient exposures are as sociated with reduced baseline lung function, exacerbation of asthma a nd premature mortality, as well as evidence from chronic animal exposu re studies at concentrations within current ambient peak levels that i ndicate progressive and persistent lung function and structural abnorm alities. The current NAAQS, if retained, may therefore also be inadequ ate to protect the public from effects resulting from chronic exposure to O3.