EXTERNAL HEALTH COSTS OF A STEEL MILL

I. INTRODUCTION This study estimates some of the external health costs associated with the operation of an integrated steel mill in Utah Valley. The mill is the largest source of particulate air pollution in Utah Valley and was closed for about a year during the period of the study. When the steel mill is in operation, the valley has relatively high wintertime particulate pollution levels. Cache Valley, a neighboring valley that is unaffected by the mill's pollution, provides an excellent comparison or control. The study evaluates temporal associations between acute care hospital admissions for respiratory diseases and the operation of the steel mill. Mortality data for both Utah County (which contains Utah Valley) and Cache County are from Utah State vital statistics. Analysis involves comparing hospitalization and mortality rates across periods when the mill was operating and across periods when the mill was closed. II. STUDY AREA Utah Valley is a mountain valley in Utah County of north-central Utah [ILLUSTRATION FOR FIGURE 1 OMITTED]. According to the Census, the county's population was about 264,000 in 1990. The most densely populated part of the county contains several adjoining cities including Provo and Orem. In 1990, these cities' combined population of approximately 223,000 was crowded into a 5-9 km wide corridor between a large fresh water lake on the west and mountains on the east. This study refers to this populated area as Utah Valley. A large, integrated steel mill is located near the center of the valley. The valley has a dry, four-season climate with temperature inversions common during winter months. During temperature inversions, the air becomes stagnant, trapping pollutants near the valley floor. In Utah Valley, extremely small, inhalable particles become highly concentrated in the air during these inversions. Because of the health risks associated with fine particles, the Environmental Protection Agency (EPA) set standards directed at particles with a diameter less than or equal to 10 micrometers ([PM.sub.10]). [PM.sub.10] standards include a 24-hour standard of 150 micrograms per cubic meter ([[micro]gram]/[m.sup.3]), and allow no more than one expected exceedance per year. The annual [PM.sub.10] standard is an arithmetic mean of less than 50 [[micro]gram]/[m.sup.3] (Environmental Protection Agency, 1987). Daily monitoring of [PM.sub.10] occurs at three sites in the valley [ILLUSTRATION FOR FIGURE 1 OMITTED]. The principal source of particulate pollution in Utah Valley is an integrated steel mill built in the 1940s. During severe winter temperature inversions, the mill contributes 50-70 percent of total [PM.sub.10] pollution (Utah Bureau of Air Quality, 1990). On August 1, 1986, a labor dispute shut down the mill. A new owner reopened the mill on September 1, 1987. When the mill was open, winter [PM.sub.10] levels were approximately twice as high as when the mill was closed. Violations of the 24-hour [PM.sub.10] standard occurred an average of 12.6 times per year when the mill was open and never when it was closed. Cache Valley, also in Utah, serves well as a control (Archer, 1990). It is approximately 150 miles north of Utah Valley, had a population of about 70,200 according to the 1990 Census, and is unaffected by the steel mill's pollution. Both Utah and Cache Valleys are mountain valleys at approximately the same elevation with populations centered around universities. Both valleys have similar climates and both commonly experience severe temperature inversions during winter months. Cache Valley has slightly cooler temperatures. Both Utah and Cache counties have low smoking rates. Based on an unpublished 1986 Utah State Department of Health survey, 5.5 percent of persons 18 years or older in Utah Valley smoke, and 9.6 percent of persons in Cache Valley smoke. These low smoking rates are due largely to the fact that the high percentage of the population in both counties are members of the Church of Jesus Christ of Latter-day Saints (Mormons), which teaches against smoking. …