RALEIGH – Emissions tests for cars and trucks are no longer necessary to protect air quality in more than half the counties where state testing is currently required.

That was the conclusion of a study the N.C. Department of Environment and Natural Resources provided the General Assembly this week.

Legislators in 2013 directed DENR to conduct a study on whether all of the counties covered under the motor vehicle emissions testing program are needed to meet and maintain current and proposed federal ozone standards in North Carolina. Cars and trucks collectively are the largest source of emissions that lead to ozone formation in the state.

“North Carolina’s air quality has improved significantly since emissions testing requirements were expanded for motor vehicles in the early 2000s,” said Donald R. van der Vaart, secretary of DENR. “We studied the air quality improvements for this report and concluded that we could eliminate emissions testing for motor vehicles in numerous counties without harming air quality or violating federal standards.”

The elimination of emissions tests would save car owners $16.40 per vehicle each year in counties where tests are currently required after the first three model years, state officials estimate. Safety inspections are still required in all 100 counties, costing owners $13.60 per vehicle each year.

The state currently requires emissions testing in 48 of its 100 counties. The DENR study determined that North Carolina could eliminate testing in 27-to-31 of those counties by Jan. 1, 2016, depending on the level at which the Environmental Protection Agency revises the current national ozone standard.

The EPA proposed a more revised ozone standard in December 2014, and plans to adopt a new standard by Oct. 1, 2015. The current ozone standard is 75 parts per billion (ppb) measured over 8 hours, and the EPA has proposed lowering (or strengthening) the standard to a level in the 65-70 ppb range.

If the EPA sets the standard at 65 ppb, DENR recommends eliminating testing in 27 counties: Brunswick, Burke, Caldwell, Carteret, Catawba, Chatham, Cleveland, Craven, Edgecombe, Franklin, Harnett, Haywood, Henderson, Lee, Lenoir, Moore, Nash, New Hanover, Onslow, Robeson, Rutherford, Stanly, Stokes, Surry, Wayne, Wilkes and Wilson. If the standard is set at 70 ppb, the recommendation includes four additional counties: Granville, Orange, Pitt and Rockingham.

Changes to the counties covered by the program would require legislative approval. The report recommends further analyses during the coming year to determine whether additional counties could be removed from the program after 2016.