The mayor of Shelby County says drifting smog from the fast-growing Mississippi county to the south is hurting a regional effort to reduce air pollution.

Mayor A C Wharton has asked the Environmental Protection Agency to declare DeSoto County in violation of air-quality standards so it must join other surrounding counties in stricter pollution-control requirements.

“Emissions do not stop at the state line,” his letter states. “Emissions from DeSoto County have some effect on ozone generation in the regional airshed.”

However, Mississippi regulators say the wind is blowing the opposite direction and DeSoto’s pollution is actually coming from Memphis.

“We can tell exactly where the emissions are coming from … ,” said Maya Rao, chief of the air division at the Mississippi Department of Environmental Quality. “They’re coming from the Memphis area.”

Wharton asked for the designation in response to an EPA proposal to reclassify the regional area made up of Shelby and Crittenden, Ark., counties, after failing to meet a deadline this year to comply with ozone standards.

The reclassification from “marginal” to “moderate” violator of air-quality standards will “place an undue and unnecessary administrative cost on the taxpayers of Tennessee and Arkansas without improving air quality in the area,” Wharton said.

Shelby County has reduced emissions of volatile organic compounds and nitrogen-oxides — the two kinds of pollutants that create ozone — between 2000 and 2006, and average ozone concentrations in Crittenden are down 3 percent since 2004.

Wharton said DeSoto has seen a “disturbing trend”: the county recorded the highest ozone concentration of anywhere in the Memphis area this year and the three-year ozone average is expected to rise above the minimum allowed by the Clean Air Act for the first time.

If the EPA had included DeSoto among the other two counties for air pollution violations three years ago, emissions from the Mississippi county’s explosive growth would be limited and restrictions would be placed on business expansion, Wharton said.

An EPA official said there are other quicker options to getting DeSoto to reduce smog than designating it in violation, which could take three years.

Kay Prince, air-quality spokesman with EPA, said a more effective strategy would be to require the county to create a plan to reduce ozone-causing emissions.

“We have found that working with states and stakeholders can be the fastest way to bring an area back into (compliance),” Prince said.