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Clean Air Act, the Foundation of Air Quality Regulations

Posted: February 23rd, 2017

Author: All4 Staff 

ALL4 prides itself on the foundational knowledge of air quality regulations and the historical perspective that accompanies the nearly 50 years of air quality laws and statutes in the United States. However, we recognize that the pool of air quality professionals that have lived these fifty years of air quality regulation is shrinking.  Regulatory agencies, industry, and consulting companies are experiencing the loss of foundational knowledge that defines the air quality expert.  Therefore, it is the commitment and standard practice at ALL4 that all of our engineers and scientists receive training in the underlying basics of air quality regulatory programs via a 12 session training program.  This air quality training program is also available to our clients as ALL4’s AQ101 webinar series.

We have extracted some of the content of our introductory AQ101 session below.  Specifically we discuss the Clean Air Act.  Some of you may also recognize some of the content as being from our Air Educator series in Pollution Engineering.  Periodically we will introduce various components of our AQ101 series as Blog postings.

The CAA and the follow-up amendments (CAAA) serve as the basis for all air quality regulations at the federal level.  The CAA represents the intent of Congress and cannot be changed unless there is Congressional action or the courts determine the law to be unconstitutional.  The basis for the CAA is contained at Title 42 of US Code (Public Health and Welfare), which is the codification of general and permanent laws of the US.  Chapter 85 of Title 42 is Air Pollution Prevention and Control.  There are six subchapters to Chapter 85 which have been added or modified by various public laws (e.g., Public Law 91-604 December 1970, the original CAA and Public Law 101-549 November 1990, the CAAA).   The six subchapters correspond to the six Titles in the CAA;

  • Title I (Programs and Activities),
  • Title II (Emission Standards for Moving Vehicles)
  • Title III General Provisions
  • Title IV and IVa (Noise Pollution and Acid Deposition Control, respectively)
  • Title V (Permits)
  • Title VI (Stratospheric Ozone)

Within Title I of the CAA are statutes addressing the National Ambient Air Quality Standards (NAAQS), State Implementation Plans (SIPs), special requirements for areas not attaining the NAAQS, hazardous air pollutants (HAPs), standards of controls for stationary sources, New Source Review (NSR) air permitting regulations for major sources, standards for solid waste incinerators, and enforcement of CAA statutes.  These components to Title I cover an enormous range of air quality issues.

Title II of the CAA addresses air quality as it relates to emissions from mobiles sources.  Oxides of nitrogen (NOX), carbon monoxide (CO), and particulate matter (PM) are addressed under Title II.  As a result of Title II, reduced levels of sulfur in fuel were achieved, renewable fuel components to gasoline were implemented, and cleaner combustion engines were developed.

Under Title III, the CAA directs how U.S. EPA should carry out its responsibilities under the CAA.  Important parts to Title III include the right of citizens to file suit for violations of emissions standards, provisions for how U.S. EPA must conduct its proceedings under other sections of the CAA, and, as noted in several recent ALL4 blogs about Appendix W to 40 CFR Part 51, address air quality modeling as related to Title I.

The control of acid deposition is the primary focus under Title IV.  Specifically, Title IV addresses the need to control emissions of NOX and sulfur dioxide (SO2).  The control of emissions is achieved by a permit program and an emissions allowance system.

Next to requirements in Title I, no other section of the CAA has impacted stationary sources more than Title V.  Under the comprehensive air permitting statutes in Title V, the various air permits at stationary sources were required to be consolidated into a single, comprehensive air permit.  Title V directed states to develop and implement their own air permitting program and to require that affected stationary sources renew their Title V air permits every five years.

Finally Title VI of the CAA addresses the protection of stratospheric ozone.  Protection of stratospheric ozone is accomplished through the regulation of ozone depleting substances categorized as either Class I or Class II.  Title VI references the Montreal Protocol for expansion of regulatory requirements to regulate ozone depleting substances.

There should be little argument that the CAA is ready for sorely needed updating.  Reliance on an understanding of Congressional intent from up to 47 years ago represents a hurdle to addressing how new air quality concerns should be addressed.  Whether it is considering climate change or evaluating if economic factors should impact air quality regulations such as the NAAQS, new Congressional intent will provide a clearer path for administering air quality for the next few decades than continued reliance on statutes from 1970 thru 1990.


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