By Bill Coates | Casa Grande Dispatch
The Arizona Department of Environmental Quality is in the process of determining who’s kicking up the most dust in Pinal County.
To that end, the agency is taking an inventory of sources for a type of pollution known as PM10, dust-size particles that can be breathed and lead to respiratory illness — severe in some cases.
In May 2012, the U.S. Environmental Protection Agency designated a large portion of western Pinal County in violation of the Clean Air Act.
DEQ had a year and a half to come up with a plan to reduce the emissions to meet EPA standards. The State Implementation Plan, or SIP, is due out in early 2014. The pollution in question is PM10, made up of particles — largely dust — that measure up to about one- seventh the width of a human hair.
Several inventories have been done over the years. DEQ is closing in on a final one for the upcoming implementation plan.
Sources for PM10 include dust kicked up on county roads, particularly dirt roads, as well as construction, industry and utility plants.
Agriculture is in the mix as well. That includes open-field farms, dairy farms and feedlots.
Cattle feeders were under pressure to tamp down fine-particulate pollution known as PM2.5. Readings for that had been high at a monitor near the Cowtown area in Maricopa, where feedlots house tens of thousands of cattle.
The EPA slapped a PM2.5 non-
attainment designation on a small area around Cowtown. But water- ing and other efforts helped to bring readings down to acceptable levels. This summer, the EPA said that area was now in compliance for PM2.5. Monitoring will continue to make sure it stays that way.
For Cowtown, PM10 is now the bigger issue.
But Bas Aja, executive vice president for the Arizona Cattle Feeders Association, questioned some of DEQ’s numbers, especially the ones that had cattle feedlots in Cowtown on the hook for some 80 percent of the PM10 reduction in that area. Air quality for Cowtown is measured by a nearby monitor. It sits off Maricopa-Casa Grande Highway.
Then Aja cited a second figure. It showed, he said, cattle feedlots contributing to 30 percent of the problem.
“The math doesn’t quite work out,” Aja said.
