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Dust Pollution Declaration Settles on West Pinal County

By Eric Jay Toll for The Arizona Builder’s Exchange

It’s the Sonoran desert. It’s the agriculture bastion of the Gila River Indian Community. Haboob-caused I-10 closures are regular occurrences. Now it’s a new nonattainment area cited by the U.S. Environmental Protection Agency and Arizona has 18 months to do something about it.

The EPA declared a portion of western Pinal County, Ariz. to be in nonattainment for the 1987 federal PM10 coarse particulate matter standard.

This is a big deal. Failure to comply impacts federal transportation dollars. With 90%+ of ADOT’s Capital Program, and most major local projects also containing federal money, there is a serious financial undercurrent. If funds were delayed or canceled, it would hit the already fragile CIP budgets very hard. EPA is not threatening to withhold funds at this time because the state is cooperating, but this is a future concern.

Public comments forced the EPA to cut the area’s size by 36 percent, but much of western Pinal County now violates standards for PM10. Air quality monitoring results showed widespread, frequent, and in some instances, severe, violations over the last decade. In fact, western Pinal County PM10 levels are among the worst in the country.

The Clean Air Act requires the state to submit a plan containing measures that will reduce airborne particulate matter until the area meets the federal air quality standard. Due within 18 months, the Arizona Department of Environmental Quality is working closely with the EPA on the plan and expects a submission soon.

The primary causes of dust pollution in the Pinal County area are from roads, agriculture, feedlots, construction and industrial processes. The final zone takes in virtually all populated areas of the county from Florence to Casa Grande and south of Apache Junction to north of Marana. GRIC, the largest agriculture producer in the area, is not included in the EPA’s nonattainment area.

EPA sets national protective standards for pollutants such as particulate matter that threaten public health. Where air quality exceeds a health-based standard, the Clean Air Act requires the area to be designated as a nonattainment area for that pollutant.

Particulate matter is the term for solid or liquid particles found in the air. Some particles are large or dark enough to be seen as soot or smoke. Others are so small they can be detected only with an electron microscope. In 1987, EPA replaced the earlier air quality standard with a PM10 standard. The new standard focused on smaller particles that are likely responsible for adverse health effects because of their ability to reach the lower regions of the respiratory tract and includes particles with a diameter of 10 micrometers or less (0.0004 inches or one-seventh the width of a human hair).

Original Source: EPA