MEMPHIS, Tenn. (AP) -- 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.

His letter declares that "emissions do not stop at the state line."

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

Wharton said DeSoto has 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.

(Copyright 2007 by The Associated Press. All Rights Reserved.)