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All Mobile Sources
Emissions from mobile sources are much lower than they would have been without
the array of control programs and solutions currently in place. The graphs below show the impact of controls on mobile source emissions of carbon monoxide, hydrocarbons, nitrogen oxides, and particulate matter. Mobile sources include both on-road and nonroad sources. In these graphs, "actual" means as things actually are, with an array of control programs in place. "Without controls" presents a hypothetical picture of what emissions would have been without existing mobile source emission control programs.
Carbon Monoxide
Mobile source carbon monoxide emissions are a little more than half what they were in 1970. Actual emissions today are four times less than they would have been without controls implemented since 1970. By 2020, carbon monoxide emissions will be a little less than they are now and about seven times less than they would have been without controls in placey
Hydrocarbons
Mobile source hydrocarbon emissions are less than half what they were in 1970. Actual emissions today are about seven times less than they would have been without controls implemented since 1970. By 2020, hydrocarbon emissions will be less than half what they are now and about 20 times less than they would have been without controls in place.
Nitrogen Oxides
Mobile source emissions of nitrogen oxides are greater than they were in 1970. This is because vehicle travel and equipment use have increased faster than progress in controlling these pollutants. Nonetheless, emissions today are half of what they would have been without controls implemented since 1970. By 2020, new emission controls are expected to have a major impact. EPA expects overall mobile source nitrogen oxide emissions to be less in 2020 than they were in 1970 and about eight times less than they would have been without controls in place.
Fine Particulate Matter
Mobile source emissions of fine particulate matter are greater than they were in 1970. This is because nonroad equipment use has increased much faster than the ability to reduce nonroad particulate emissions. The increase in nonroad emissions has even overwhelmed considerable progress in reducing particulate emissions from on-road sources. Nonetheless, overall mobile source particulate matter emissions today are less than half of what they would have been without controls implemented since 1970. And by 2020, new emission controls are expected to have a major impact. EPA expects overall mobile source particulate emissions to be only slightly higher in 2020 than they were in 1970, and about four times less than they would have been without controls in place.