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Show Health Risk from Air Pollution in Utah by Steven C. Packham, Ph.D, D.A.B.T. Introduction The most prevalent air contaminants regulated by law in Utah are carbon monoxide (CO), ozone and PM10 (i.e., particles in the air that are 10 microns or smaller in diameter which can be breathed deep into the lungs). In addition to CO, ozone and PM10, there are national standards for lead, oxides of sulfur and oxides of nitrogen. Most air pollution comes from either industrial and commercial processes, or from cars, trucks, construction equipment, lawn mowers, or other equipment which burn petroleum products as fuel. Each of these pollutants can adversely affect health. Air quality professionals develop inventories of pollution emissions from all known types of sources through engineering calculations, surveys, computer models and direct measurements. Environmental laws require states to reduce emissions and document reductions in emissions inventories in areas of the state where air pollution exceeds the national health standards or where pollution is considered to be a threat to public health or the environment. There are four counties and three cities in Utah that have historically exceeded one or more of the National Ambient Air Quality Standards (see Figure 1). In the last 15 years there has been improvement in air quality in these areas as indicated by the number of times air pollution has exceeded the national standards (Table 1). Table 1. Number of exceedances in non-attainment areas per year. Performance Measures 1980 1990 1995 CO-carbon monoxide 30 14 0 PMlO-fine paniculate 26 0 0 matter O3-ozone 17 1 3 SOx-oxides of sulfur 2 0 0 NOx-oxides of nitrogen 0 0 0 Pb-lead 0 0 0 This improvement, despite population growth, has been achieved through stricter pollution controls on cars and on industries. Population growth predicted for Utah into the next century poses the greatest pressure on rising pollution inventories. The Division of Air Quality is developing "maintenance" plans as part of its State Implementation Plan to assure that air quality is not compromised as the state continues its economic growth. Health Effects and Standards Carbon monoxide, ozone and PM10 differ in how persistent they are in the air and in their health effects. The level of protection offered by federal standards also varies for these pollutants. Carbon monoxide is produced directly from burning fuels such as gasoline and wood-burning stoves. It is ubiquitous in all urban areas and CO produced today can stay in the air for over a month. Winds move CO pollution from its various sources to far distances. It is basically air movement, rather than CO decay, which keeps urban CO levels as low as they are. In contrast, ozone is not formed directly from cars or industry, but is a by-product of a chemical reaction between two other groups of pollutants, volatile organic compounds and oxides of nitrogen. This reaction is driven by sunlight and high summer temperatures. Ozone is formed in the afternoon on hot summer days and decays overnight when the temperature drops and the sun goes down. PM10, unlike CO or ozone, is not a homogeneous substance. It is made up of particles from many different sources. It can include chemically neutral particles similar to little rocks and grains of sand, and it can include chemically potent particles made from condensing gases. The chemical and physical nature of the particles included in PM10 varies from city to city, county to county and from day to day within those areas depending on weather conditions. The persistency of PM10 in the air depends on how much the particles weigh, on whether they are solid or volatile and on where, when and how they are made. The health effects and the level of protection possible from air standards also differ greatly for these air pollutants. Carbon monoxide displaces oxygen in the blood and prevents the blood from carrying oxygen from Utah's Health: An Annual Review 1996 21 |