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Chief Causes for Concern
Carbon Monoxide
- CO Home
- Emission Sources
- Causes for Concern
- Health & Enviro Impacts
- EPA Efforts to Reduce CO
- EPA Offices
CO. . .
- is poisonous even to healthy people at high levels in the air.
- can affect people with heart disease.
- can affect the central nervous system.
Nationwide, three-quarters of carbon monoxide emissions come from on-road motor vehicles (cars and trucks) and non-road engines (such as boats and construction equipment). Control measures have reduced pollutant emissions per vehicle over the past 20 years, but the number of cars and trucks on the road and the miles they are driven have doubled in the past 20 years. Vehicles are now driven two trillion miles each year in the United States. With more and more cars traveling more and more miles, growth in vehicle travel may eventually offset progress in vehicle emissions controls.
Malfunctions and Tampering Reduce
the Effectiveness of Emission Control Systems
Today's sophisticated emission control systems on vehicles are designed
to keep pollution to a minimum, but vehicles quickly become polluters when
their emission controls do not work correctly or if drivers tamper with
them.