Clean Air Act (CAA)

The Clean Air Act (CAA) U.S.C. Title 42, Chapter 85

A part of Environmental Law, the CAA is a massive piece of legislation from the 1970s, that promulgates uniform national standards for a wide range of air pollutants and sources, through a handful of systems.  The CAA uses a two prong attack - in addition to regulating the air quality levels, it also allows regulate sources of pollution. 
 

National Ambient Air Quality Standards (NAAQS)

This is method of regulating criteria pollutants (ones that both "endanger the public health or welfare" and are "emitted from numerous or diverse sources"), by requiring them to stay below a level set to "protect the public health" with an "adequate margin of safety".  Under §108, the EPA is required to consider adding pollutants to the criteria list.  See Lead Industries of America v. EPA (647 F.2d 1130 (D.C.Cir 1980)) in which the court held that while the EPA must regulate levels of lead, they had discretion in determining what was an adequate margin of safety.  There are currently 7 criteria pollutants.

• There are two types of NAAQS: Primary standards (which protect human health) and secondary standards (which protect the public welfare, which includes effects on animals, wildlife, water and visibility).

State Implementation Plans (SIPs)

Although the NAAQS call for a uniform protection, this is moderated by State Implementation Plans (See §110) which allows each state to determine the emission standards that are required for that state to meet the federal standard level of air quality.  States have the discretion to require a higher level of air quality, but may not go below the federal standard.

• If the EPA feels the SIP will not achieve the NAAQS, they may begin a process establishing a Federal Implementation Plan (FIP), and take over the regulation plan.
• Areas that are in compliance with the NAAQS are known as "attainment area" and areas that are not are known as "non-attainment areas".  The attainment and non-attainment areas are subject to different levels of regulation. 
   

Stationary Sources

Here, the level of pollution control technology required depends on if the area is an attainment area or a non-attainment area.

• Attainment areas are focused on Prevention of Significant Deterioration (PSD), or maintaining their high quality of air.  These areas require Best Available Control Technology (BACT).
• Non attainment areas are focused on cleaning up the air by requiring higher standards.  New / modified major sources must employ control technology with the "lowest achievable emission rate" (LAER), and existing sources must use "reasonably available control technology" (RACT). 

Mobile Sources

Here, the EPA focuses on both the fuel going into the car / truck / vehicle, and the emissions that are coming out.  In a major case, Mass v. EPA (549 U.S. 497 (2007)), the Supreme Court held that not only did the EPA have the authority to regulate the emissions of carbon dioxide, but under the CAA they were were required to do so.  The EPA had previously declined to regulate on a variety of grounds including that it was unwise to do so given the current uncertainty about greenhouse gas issues; but the court rejected theses arguments and required the EPA to regulate.