What type of testing is required for diesel vehicles?
All diesel-fueled vehicles equaling 10,000 pounds or less must be tested through the E-Check program if they are registered in one of the 7 E-Check counties. Model year 1996 and older diesel-fueled vehicles are given an opacity test to determine the “density” of the exhaust emitted from the vehicle’s tailpipe. Opacity is defined as the percentage of light transmitted from a source which is prevented from reaching a light detector. The major environmental concern with diesel-fueled vehicles is the particulate matter emitted as a result of combustion. Particulate matter includes microscopic particles and tiny droplets of liquid. Because of their small size, these particles are not stopped in the nose and upper lungs and may end up in the lower lungs. These particles can then become trapped and cause irritation. Exposure to particulate matter can cause wheezing and similar symptoms in people with asthma or other forms of Chronic Lung Disease. Beginning January 5, 2004, model year 1997 and
