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Nonroad Sources
The first efforts to control pollution from nonroad vehicles, engines, and equipment started in the early 1990s, some 20 years after on-road emissions control requirements began to take effect. Consequently, while on-road emissions are generally lower now than they were in 1970, nonroad emissions are much higher. Nonroad control programs are starting to catch up, however. These programs should start to yield big emission reductions in the future.
The graphs below show the impact of controls on nonroad vehicle, engine, and equipment emissions of carbon monoxide, hydrocarbons, nitrogen oxides, and particulate matter.
Nonroad sources include a wide variety of categories including industrial, lawn and garden, construction, recreational, and farm equipment. 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 emission control programs.
Carbon Monoxide
Nonroad carbon monoxide emissions are more than twice what they were in 1970 and will continue to increase in the future. This is because growth in equipment use has increased faster than progress in controlling this pollutant. Nonetheless, emissions today and in the future are less than they would have been without controls in place.
Hydrocarbons
Nonroad hydrocarbon emissions are almost twice what they were in 1970. This is because growth in equipment use has increased faster than progress in controlling this pollutant. Nonetheless, emissions today are less than they would have been without controls implemented during the last 10 years. By 2020, nonroad hydrocarbon emissions will be less than they are now and less than half what they would have been without controls in place.
Nitrogen Oxides
Nonroad emissions of nitrogen oxides are close to five times higher than they were in 1970. This is because growth in equipment use has increased faster than progress in controlling these pollutants. Nonetheless, emissions today are less than they would have been without controls implemented during the last 10 years. By 2020, nonroad nitrogen oxide emissions will be less than they are now and less than half what they would have been without controls in place.
Fine Particulate Matter
Nonroad emissions of fine particulate matter are nearly triple what they were in 1970. This is because growth in equipment use has increased faster than progress in controlling of this pollutant. Nonetheless, emissions today are less than they would have been without controls implemented during the last 10 years. By 2020, nonroad particulate matter emissions will be about the same as they are now and roughly two-thirds of what they would have been without controls in place.