Conference on health effects of acid precipitation. November 15-16, 1984, Research Triangle Park, North Carolina.

The papers in this issue of Environmental Health Perspectives EHP on potential health effects from acid rain are from the Conference on Health Effects of Acid Precipitation held at the National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, in November 1984. The planning began about a year earlier as an outcome of a small workshop to discuss whether or not the potential for human health effects from acid rain was a credible research topic. The report of this workshop is published in a previous issue of EHP and serves as the background for this conference. Acid rain has become a household word in recent years and one can easily gain the impression that it is a new problen. Actually, it may be an old problem whose growth has been insidious. The phenomenon was probably recognized more than 100 years ago. John Louma, in his recent monograph, Troubled Skies and Troubled Waters, The Story of Acid Rain, (1) cites a book published in 1872 called Air and Rain, The Beginnings of Chemical Climatology. The author ofthe book was Robert Angus Smith, a general inspector of alkali works for the British government, and it addresses such topics as "Air of London," "Air of Impure Places," and "Bad Air and the Sensations." Smith is supposed to have identified the phenomenon of acid rain and coined the term "acid rain." Little recognition was given to the problem again until the mid-1950s with the deadly "London Fog" episode. Since that time, the phenomenon has been quite visible and has received considerable attention, first in Europe beginning some 25 years ago, and in the United States over the past 10 years. An importamt point for emphasis is that acid rain is a phenomenonnot a toxic substance per se-but it can be the raison d'etre for increased human exposure to air pollutants and toxic metals. Therefore, research which addresses the human health effects of the acid rain phenomenon is not separable from investigations of the involved specific toxic substance. On the other hand, the acid rain phenomenon contributes to human exposure to these substances so that any consideration 9f the impact of the acid rain phenomenon on human health must involve