Air Care Colorado

Emissions Limits for Heavy-Duty Vehicles

Heavy-duty vehicles are defined as having a Gross Vehicle Weight (GVW) of greater than 8,500 lbs. for 1979 and newer vehicles, or greater than 6,000 lbs. for 1978 and older vehicles. Heavy-duty vehicles are tested with the two-speed idle test rather than the I/M 240 test. Pollutants are sampled and measured in parts per million. Heavy-duty vehicles include most motorhomes.

The following chart shows the emissions limits for carbon monoxide (CO) and hydrocarbons (HC) by vehicle model year. Although emissions limits are listed here for only 1967 through 2011 model year vehicles, all older vehicles are subject to testing unless they fit certain testing exemption categories. Oxides of nitrogen (NOx) are not tested for heavy trucks.

Model YearCOHC
1986 & Newer2.0300
1981 - 19853.0600
1970 - 19785.51000
1968 - 19696.51200
1967 & Earlier7.01500

CO: carbon monoxide   HC: hydrocarbons
Source: Colorado Department of Public Health and Environment