Hamilton County might be affected by EPA smog rule

photo Bob Colby

Local air quality experts say proposed Environmental Protection Agency rules for controlling ground-level ozone could be troublesome for Hamilton County, but only if regulators settle on the lower end of proposed standards.

Federal regulators are considering lowering the acceptable limit of ozone content in air from its current 75 parts per billion limit - a standard the county meets - to as low as 65 ppb.

"They are taking comments on a range of [ozone] levels to set the standard at. The proposal is 65 ppb to 70 ppb, and we are currently at 69 ppb," Chattanooga-Hamilton County Air Pollution Control Bureau Director Bob Colby said Wednesday. "If they set it below 69 ppb, we'll have some additional work to do."

But even if the new limits are set below current local levels, Colby said, noncompliance wouldn't happen overnight.

The county would have until 2020 to get into attainment, and he said the county historically has been reducing its ozone levels annually.

But he added that time frame - much like the rest of the proposal - is still up in the air. No decisions will be made until next year, he said.

"Sometimes these things get slowed down, and sometimes they get sped up. We just have to wait and see," Colby said.

If the county is out of compliance under the new rules, it would not be the first time.

Hamilton County signed an agreement with the EPA and the state in 2005 to mitigate perpetual air quality problems. At the time, the county had fallen short of federal guidelines for ozone.

Part of the agreement requires vehicle emissions testing - a point of much contention among residents and local politicians alike. The county entered its current five-year agreement with the state, which oversees the emission testing facilities, in May 2013.

Colby told county commissioners last year that if the county went out of compliance with EPA air quality rules, new industries would not be able to set up shop in the county because they could not receive permits from the EPA.

Contact staff writer Louie Brogdon at lbrogdon@timesfreepress.com or 423-757-6481.

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