Clean Air Act

The Clean Air Act, national legislation passed in 1970, created the provisions for air quality standards and monitoring in the U.S.

The Act requires the federal government to establish standards called the National Ambient Air Quality Standards and requires states to develop a State Implementation Plan to meet these standards.

There are six criteria pollutants regulated under the Act:

  • particulate matter
  • nitrogen oxides
  • sulfur dioxides
  • lead
  • ozone
  • carbon monoxide

Diesel engines are a source of some of these pollutants, but newer diesel engines are 90% (or more) cleaner than older models.

U.S. EPA regulations require all on-road diesel heavy duty vehicles made since 2007 to have a filter installed from the factory that reduces particulate matter by 95%.  In addition, all 2010 on-road diesel heavy duty vehicles are required to have nitrogen oxide (NOx) controls which reduce this pollution by about 85%.

Similarly there are emission reduction requirements for non-road equipment as well. These regulations will be fully phased in by 2015.

Despite these gains, the U.S. EPA estimates the full health benefits will not be realized until at least 2030 because diesel engines last 30 to 40 years.  

Several counties in Ohio are expected to fail the revised particulate matter (PM) 2.5 (soot) and ozone standards. Failure to meet the Clean Air Act could mean the expansion of E-check, including car inspection-maintenance program, pollution controls on large facilities, and the possibility of federal highway funds being withheld from the state. 

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