Preliminary results released Monday found that air quality would worsen if the state cut tailpipe testing and implemented other emission controls, said Kevin Crist, director of the Air Quality Center at Ohio University, which conducted the study.

Since 1996, the state has required tailpipe testing in seven counties around Cleveland and seven in the Cincinnati area.

"What we're seeing is, even with E-check, there's going to be potentially more programs needed. E-check by itself is not enough," Crist said.

The state Environmental Protection Agency paid $14,000 for the study, which is based on ozone data from the past three years, Crist said. The full report will be released in about two weeks.