Introduction
On March 20, 1984, the US Environmental Protection Agency (EPA) proposed changes in the national ambient air quality standards for particulate pollution. Total suspended particulates (TSP) was to be replaced with a new indicator of particulate pollution that includes only those particulates with an aerodynamic diameter equal to or less than a nominal 10 micrometers (PM10). On July 1, 1987, the EPA announced its final decision. The previous primary TSP standards were to be replaced, effective July 31, 1987, with a 24-hour PM10 standard of 150 micrograms per cubic meter (,ug/m3) with no more than one expected exceedance per year and an annual PM10 standard of an expected arithmetic mean of 50 ,ug/m3.'
Earlier studies of the health effects of particulate pollution2' revealed a possible connection between air pollution and human health, and launched a wave of research exploring this connection.919 Recent research has observed that even moderately elevated concentrations of particulate pollution may result in reductions in children's pulmonary function20'2' and increased risk for bronchitis and other respiratory illnesses.22 Other recent research questions the existence of a threshold level.
Previous studies have not used PM1O as an indicator of particulate pollution. Recent experiences in Utah County have provided a unique opportunity to investigate a possible association between respiratory health and different levels of PM10. Utah Valley has had daily monitoring of PM10 since April 1985; it has an extremely low percentage of smokers; it has experienced a prolonged shut-down and then reopening of the steel mill, its largest source of particulate pollution; over time, since monitoring of PM10 began, the valley has experienced considerable variability in levels of fine particulate pollution; and hospital inpatient admissions data for respiratory illnesses can be obtained. The objective of this paper is to report what has been observed in Utah Valley with respect to hospital admissions for respiratory illnesses and PM10 levels.
Introduction
On March 20, 1984, the US Environmental Protection Agency (EPA) proposed changes in the national ambient air quality standards for particulate pollution. Total suspended particulates (TSP) was to be replaced with a new indicator of particulate pollution that includes only those particulates with an aerodynamic diameter equal to or less than a nominal 10 micrometers (PM10). On July 1, 1987, the EPA announced its final decision. The previous primary TSP standards were to be replaced, effective July 31, 1987, with a 24-hour PM10 standard of 150 micrograms per cubic meter (,ug/m3) with no more than one expected exceedance per year and an annual PM10 standard of an expected arithmetic mean of 50 ,ug/m3.'
Earlier studies of the health effects of particulate pollution2' revealed a possible connection between air pollution and human health, and launched a wave of research exploring this connection.919 Recent research has observed that even moderately elevated concentrations of particulate pollution may result in reductions in children's pulmonary function20'2' and increased risk for bronchitis and other respiratory illnesses.22 Other recent research questions the existence of a threshold level.
Previous studies have not used PM1O as an indicator of particulate pollution. Recent experiences in Utah County have provided a unique opportunity to investigate a possible association between respiratory health and different levels of PM10. Utah Valley has had daily monitoring of PM10 since April 1985; it has an extremely low percentage of smokers; it has experienced a prolonged shut-down and then reopening of the steel mill, its largest source of particulate pollution; over time, since monitoring of PM10 began, the valley has experienced considerable variability in levels of fine particulate pollution; and hospital inpatient admissions data for respiratory illnesses can be obtained. The objective of this paper is to report what has been observed in Utah Valley with respect to hospital admissions for respiratory illnesses and PM10 levels.
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