Air Team inspectors are certified to perform the test and must complete 80 hours of classroom and hands-on training. They must pass written and practical tests to become certified. To simulate actual driving conditions, a treadmill device called a dynamometer is used. The drive wheels are placed on the dynamometer while a hose collecting the vehicle's emissions is placed on the tailpipe. Because the vehicle is accelerating and decelerating, some side to side movement is normal.
Inspectors follow a predetermined course that simulates city and highway driving.
The drive part of a single test takes from a minimum of 31 seconds to a maximum of 240 seconds. More than one drive test is sometimes administered. Most vehicles in good condition pass the test in less than one minute. The first part of the test, which simulates city driving, never exceeds 33 mph. The last part of the test, which simulates highway speeds, never exceeds 57 mph.