Feasibility of epidemiological monitoring for a proposed coal-fired power plant, Ivanpah, California

Abstract

The authors were asked to determine the feasibility of conducting epidemiologic monitoring for adverse health impact of emissions from the proposed Ivanpah Coal-Fired Power Plant. The study was required by the licensing agency, and specifically concerned health effects on the surrounding community. No potential occupational effects were considered. The area of concern was limited by the licensing agency to a circle of 50 mile radius around the Ivanpah site. The proposed power plant will be capable of generating 1500 megawatts of electricity utilizing low sulfur western coal. It is designed with stack heights of 500 feet for good dispersion and is planned to be outfitted with the best available stack emission control equipment. To establish whether an epidemiologic study is feasible, one must determine: (1) the size of the population which potentially would be exposed; (2) the pollutants to which that population might be exposed and the expected level of exposure and (3) the known or expected health effects of these pollutants and the frequency of such health outcomes. In addition, as in any epidemiologic study, the choice of a proper comparison group, the acceptability of a study to the population to be monitored and costs of the study in relation to available resources must also be taken into account. The population residing within 20 miles of the site consists of approximately 1,500 people at the present time. This population is not expected to increase significantly, although there is the possibility of growth of a “company town” surrounding the plant. Such an event would clearly alter the feasibility of conducting an epidemiologic study. Air quality modeling was used to predict the exposures to the population from various emissions from the proposed generating station. It was based on worst-case assumptions of wind speed, direction, atmospheric stability and percent sulfur-content coal. While a great many pollutants may result from coal burning, the levels of all pollutants, with the possible exception of ozone, are expected to be much lower than existing standards allow and therefore of little practical concern in the communities near Ivanpah. Since ozone is not a primary pollutant but is of secondary origin, its concentration, given the appropriate conditions, could increase with distance from the plant. None of the expected health outcomes occurs with sufficient frequency to allow the detection, with a reasonable degree of statistical certainty, of any reasonably expected increase in frequency in an epidemiologic study of a population as small as that which is associated with the Ivanpah site. Furthermore, the 1,500 “local” residents are distributed in several considerably smaller population clusters at different directions from the site. These population centers would be expected to have quite different probabilities of exposure and therefore should probably not be considered as one population. With such small populations, if any health effects developed due to the plant, the increases which could be detected with reasonable certainty in an epidemiologic study are so large as to be obvious even without study. Specific recommendations for environmental monitoring are made and feasibility should be re-evaluated within five years of operation of the plant if and when built.