PM-10 particles are smaller in diameter than a human hair. When inhaled into the lungs, they can cause concerns that include: effects on breathing and respiratory systems, damage to lung tissue, cancer and premature death.

However, the damage these particles cause is not limited to health aspects. They can also be financially crippling to cities, counties and states with air quality violations.

PM-10 particles are thrust into the air by sources such as fugitive dust from unpaved roads, vacant lots, dust tracked out onto paved roads, disturbed areas on mining sites, construction sites and windblown dust from agricultural fields.

The Environmental Protection Agency (EPA) tracks the concentration of these particles by using a series of meters spread across the United States. They look at the average concentration levels of the particles during a 24-hour period. Meters are allowed to exceed the maximum concentration level three times in three years, but the fourth time leads to further investigation by the EPA.

Pinal County's eight meters are some of the most active in the United States, indicating five of the top eight worst air quality readings.

Two of those hyperactive meters are located in Maricopa. The Cow Town meter is located at the corner of the Maricopa-Casa Grande Highway and Hartman Road, and the Maricopa meter is located behind the Pinal County sheriff's substation.

The Cow Town meter is the most active in the United States with nearly 222 days each year of exceedance; the second highest meter reading in the country has 49 days per year of exceedance.

"We all know why that Cow Town meter is so active. I think the placement of these meters needs to be questioned," said Maricopa City Council member Carl Diedrich.


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