The controversial test becomes mandatory Oct. 1. All gasoline-powered cars and trucks built since 1984 will be tested every two years. Motorists will pay $12 per test.
Maryland began testing emissions from the tailpipes of idling vehicles in 1984, but Washington County wasn't included in the program until last year. This year the state moved to expand the program so that cars are placed on giant rollers, called dynamometers, so that emissions can be tested at highway speeds.
Environmental experts say the treadmill is a better test because it detects pollutants, such as nitrogen, which are not detected from an idling vehicle. Mandatory treadmill testing is expected to reduce air pollution across the state by 71 tons a day, compared to the 16-ton-a-day reduction realized through testing of idling vehicles, state officials said.
"This is the biggest bang for the buck," MVA spokeswoman Karen Coyle said.
Many motorists have blasted the treadmill test for being intrusive, time-consuming and potentially damaging to vehicles. Many local people and elected officials have questioned why the county - the westernmost in the state in the vehicle-emissions program - needs to test for auto emissions.
The county is included in the emissions program because it has densely populated areas where there are as many vehicles as there are residents, said Peggy Lord, an air pollution official with the state Department of the Environment.
She said a third of ground-level pollution, or smog, is generated from automobiles.
Ferro said complaints about the test taking too long have been addressed, and the average waiting time for motorists is now about five minutes. Of the 500,000 cars tested on the treadmill so far, 240 owners reported some kind of damage, she said.
Despite the complaints, the county leads the state in voluntary treadmill testing, with about 70 percent of the motorists who take their cars to the emissions center west of Hagerstown opting for the dynamometer, Ferro said.
"The majority of your vehicle owners are already familiar with the treadmill, which has set the standard for the rest of the state," she said.
Sandra Collins, a Hagerstown resident who brought her truck to the testing center Tuesday morning, said she had no problem going through the dynamometer. She was unaware of any controversy.
"I don't know anything about it," Collins said.