Chapter 11 - § 11.2 • AIR QUALITY

• Jurisdiction: Colorado

§ 11.2 • AIR QUALITY

§ 11.2.1—Clean Air Act (Federal)

The Clean Air Act Amendments of 1990 (CAA)¹ created a sweeping revision of the federal program regulating air pollutants and expanded the scope of regulation far beyond the traditional industrial smokestack to encompass smaller emission sources, such as gas stations and dry cleaners. The Environmental Protection Agency (EPA) is diligently implementing the amended Act, which also required amendments to the Colorado Air Pollution Prevention and Control Act.² Significant components of the Act include an expanded permit program, strict regulation of toxic air pollutant emissions, provisions designed to encourage the use of alternative fuels, acid rain controls, a program to phase out ozone-depleting substances, and more stringent enforcement provisions.

Title I of the CAA is designed to minimize air pollution in urban areas. Section 109 requires the EPA to establish National Ambient Air Quality Standards (NAAQS) for pollutants necessary to protect public health, with an adequate margin of safety, and to protect public welfare from any known or anticipated adverse effects.³ Based on this authority, the EPA has promulgated NAAQS for six pollutants or groups of pollutants: sulfur dioxide (SO2), particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), carbon monoxide (CO), ozone, and lead. In turn, states are responsible for attaining the standards under Section 110 by creating State Implementation Plans (SIPs).⁴ Cities that fail to meet the standards are called nonattainment areas, which are classified by the degree of nonattainment for each of the three pollutants. There are five classifications for ozone⁵ and two for CO and PM10.⁶ Each classification is assigned controls to ensure minimum annual progress. Deadlines to meet emission standards range from three to 20 years. All Colorado communities are in attainment of all NAAQS with the exception of the Denver Metropolitan/Northern Front Range area. In December 2019, the Denver Metropolitan/Northern Front Range area was reclassified from a Moderate to a Serious Nonattainment area for the 2008 ozone NAAQS.⁷ The State of Colorado must now submit SIP revisions under the new classification and implement related control requirements to achieve lower ozone levels.

Section 112(l) of the CAA allows states to develop programs to enforce emission standards and to prevent releases of extremely hazardous substances. State standards must be as stringent as the federal standards promulgated, and the state must have adequate authority and resources to implement the CAA programs.⁸ The CAA requires operating permits for all existing sources that emit pollutants in excess of threshold quantities.

The permits mandated by the CAA require the owner or operator of a source to control emissions by installing control technology, restricting operations, or by other methods acceptable to the regulating agency. The degree of control required depends on the type and amount of pollutants emitted, the type and location of the source, and other criteria. All operators of sources, both large and small, may need CAA permits for their operations. For example, typical existing sources requiring permits include dry cleaners, gas stations, oil refineries, factories, chemical plants, hospitals and other health care facilities, utilities, paper mills, smelters, breweries, and brickyards.

Under the acid rain deposition control provisions, certain municipally owned power plants qualify for bonus allowances.⁹ In addition, any municipally owned sources are subject to the state's permitting program. These include any premises where power is used or generated (e.g., schools, local government buildings, public parks, and assembly halls). Municipalities may also be involved in financing pollution-abatement facilities and equipment through the sale of municipal bonds.

§ 11.2.2—Federal Regulation of Greenhouse Gases

The EPA continues to evaluate how to regulate greenhouse gas emissions under the CAA as a result of the landmark U.S. Supreme Court decision Massachusetts v. Environmental Protection Agency.¹⁰ In that case, 12 states and several cities brought suit against the EPA to force the EPA to regulate carbon dioxide from automobile emissions as "air pollutants." The Court held that EPA had authority under the CAA to regulate greenhouse gas emissions. The Court held that greenhouse gases are "air pollutants" as that term is used in the Clean Air Act and ruled that unless the EPA concludes that greenhouse gases are not causing climate change, the EPA must regulate greenhouse gas emissions under the CAA.

Following the Court's decision in Massachusetts v. Environmental Protection Agency, the EPA has issued and proposed regulations to limit greenhouse gas emissions from stationary sources. In September 2013, the EPA proposed regulations governing carbon emissions from new power plants, and those rules were finalized in 2015.¹¹

The EPA also issued rules setting greenhouse gas emission thresholds that trigger the need for emissions limitations under CAA permits under the New Source Review, Prevention of Significant Deterioration (PSD), and Title V operating permit programs for new and existing individual facilities.¹² These rules continue to be the source of a...