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Module 7: Regulatory Requirements - Title I: National Ambient Air Quality Standards
National Ambient Air Quality Standards
State Implementation Plans
Recent EPA Regulatory Actions
Cap and Trade Program
Practice Problems
Objectives
- Name the seven criteria pollutants for which EPA has promulgated
a NAAQS.
- Describe five recent regulations associated with NAAQS.
- Explain how the various Title I regulations are interrelated.
- List the criteria for companies to qualify for the Cap and Trade program.
National Ambient Air Quality Standards
Beginning with the Clean Air Act of 1970, Congress charged EPA with the responsibility of establishing uniform National Ambient Air Quality Standards (NAAQS). These standards were set for a group of common air pollutants, which are emitted by numerous, diverse stationary sources and mobile sources. Primary standards for each pollutant were established at low ambient levels considered necessary to protect public health. Secondary standards were established at slightly higher levels in order to protect community property and welfare (materials and crops).
By the end of 1990, EPA had identified six criteria pollutants and had promulgated NAAQS under Title I for each. The six original criteria pollutants are sulfur dioxide, nitrogen oxides (NOx), carbon monoxide, ozone, lead, and PM10. Criteria pollutants are used as indicators of air quality. In July 1997, EPA promulgated a NAAQS for PM2.5, making it the seventh criteria pollutant. EPA also revised the NAAQS for nitrogen oxides and ozone at that time. As of the writing of these modules (December 1999), a District of Columbia court has remanded these new NAAQS standards. These NAAQS are currently under litigation. Air quality standards are presented in these modules as they were promulgated by the EPA, with no presumptions made regarding the outcome of the pending litigation.
The NAAQS standards are based on comprehensive studies of available ambient monitoring data, health effects data, and material effects studies. The published versions of these studies are called Air Quality Criteria Documents. The term, criteria pollutants, has been derived from these regulatory support documents.
Following the 1970 CAA each state was required to adopt and submit to EPA a plan providing for the implementation, maintenance, and enforcement of standards to attain and subsequently maintain the various NAAQS. These plans were termed the state implementation plans or SIPs. Each of these plans included a detailed pollutant source emission inventory, demonstration modeling/calculation results, monitoring programs, a summary of the control strategy to be used to achieve the NAAQS in the required time, and a summary of the state's legal authority to administer and enforce the plan. Thus, each state directed its control regulations and approach toward its unique set of emission sources and circumstances. EPA reviewed these plans to confirm that they were reasonably designed to achieve the NAAQS.
The 1990 CAAA have had a marked impact on the SIPs. States have been required to modify these plans with regards to the provisions affecting compliance with the ozone, particulate matter, and carbon monoxide standards. These three pollutants have proven to be especially difficult to control due to the variety of urban sources that can emit these pollutants and photochemical precursors of these pollutants.
Recently, EPA has promulgated or is in the process of promulgating five separate, but highly interrelated regulatory actions involving the NAAQS.
- NOx SIP Call and related regulatory actions
- Section 126 Petitions from eleven eastern states to EPA
- Revised Ozone National Ambient Air Quality Standards, July 1997
- National Ambient Air Quality Standards, July 1997
- Regional Haze Rulemaking
On September 28, 1998, EPA issued a formal call for revised State Implementation Plans (SIPs) concerning nitrogen oxides to 22 eastern and midwestern states and the District of Columbia. This rulemaking is referred to as the NOx SIP Call. It was the result of more than two years of negotiations among EPA and State representatives from 37 states comprising the congressionally mandated organization titled Ozone Transport Assessment Group (OTAG). EPA has relied substantially on OTAG in developing the specific requirements included in the NOx SIP Call.
The purpose of the NOx SIP Call is to reduce the amount of ground level ozone formed during regional transport of air masses. This rulemaking is part of a continuing trend by EPA to control ozone by minimizing NOx emissions rather than volatile organic compound (VOC) emissions. VOC control was the main technique applied from 1971 to 1990. EPA now recognizes that due to biogenic sources, ambient VOC concentrations are more widespread and more difficult to control than ambient NOx concentrations.
The final ruling on the Regional NOx Emission Reduction (NOx SIP Call) identifies the 22 states, shown in Figure 1, that "contribute significantly" to ozone problems in downwind areas. These states must develop strict NOx control requirements applicable to stationary sources in order to minimize ozone emissions during the summertime ozone season, which is defined as May 1 through September 30 in the Northern hemisphere. During this time period the photochemical reactions causing ozone formation are most effective due to high solar irradiation rates and high ambient temperatures.
The NOx SIP Call requires the affected states to prepare and submit a revised SIP to EPA that addresses how they will reduce the transport of NOx emissions across state boundaries.
In its SIP each individual state has the freedom to meet the requirements of this rule by reducing emissions from the sources they choose. However, EPA has, to a major extent, preempted their choices by publishing a proposed Federal Implementation Plan (FIP). The proposed FIP would be imposed on a state that failed to submit a SIP to EPA.
Eleven northeastern states (Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont) have filed petitions seeking to reduce the amount of ozone transported into their state boundaries called the Section 126 Petitions. These states requested that EPA make a finding that NOx emissions from certain stationary sources in other states significantly contribute to their ozone nonattainment problems. Although the Section 126 Petitions and the NOx SIP Call are driving toward a similar result, EPA is addressing each action independently.
In July of 1997, EPA repromulgated the ozone NAAQS. This rulemaking established a new eight-hour average ozone limitation of 0.08 ppm. Compliance with this limitation is determined based on the fourth-highest daily maximum 8-hour average measured ozone level in a region over a three-year period. Areas throughout the East, South and Midwest are expected to have ozone levels above this value. Certain metropolitan areas with limited natural dispersion (e.g. Los Angeles and Denver) are also expected to exceed the new eight-hour limit.
As part of this rulemaking, EPA repealed the one-hour standard of 0.12 ppm for those areas already in attainment. The one-hour standard is based on the fourth-highest daily maximum 1-hour average measured ozone level in a region over a three-year period. The one-hour standard will be phased out in other areas as they also come into attainment. The new eight-hour NAAQS is now in effect throughout the U.S. The areas that are not yet in attainment retain the one-hour standard.
A District of Columbia court remanded the new NAAQS for ozone in May of 1999. This NAAQS is under litigation as of the writing of these modules (December 1999). Air quality standards are presented in these modules as they were promulgated by the EPA, with no presumptions made regarding the outcome of the pending litigation.
Attainment of the ozone NAAQS is highly related to the NOx SIP Call, in which 22 states participate. In many cases, it is anticipated that the implementation of new controls for the NOx SIP Call will simultaneously provide compliance with the ozone NAAQS.
Regions of the country having especially severe ozone problems due primarily to motor vehicle emissions continue to be subject to the one-hour ozone NAAQS in addition to the newly promulgated eight-hour NAAQS. The time period for implementation of controls is considerably longer in these regions. Compliance by May 2010 is required for these areas. These areas include ten metropolitan areas listed as "Extreme," "Severe 17," or "Severe 15" in Table 1.
During July of 1997, EPA promulgated a new NAAQS for PM2.5 because EPA believes that these fine and ultrafine particles are closely related to significant adverse health effects. Accordingly, EPA has established a 24-hour average limit of 65 micrograms per cubic meter and an annual average limit of 15 micrograms per cubic meter. Controls for PM2.5 will probably not be established until the 2005 to 2008 time period.
A District of Columbia court remanded the NAAQS for PM2.5 in May of 1999. This NAAQS is under litigation as of the writing of these modules (December 1999). Air quality standards are presented in these modules as they were promulgated by the EPA, with no presumptions made regarding the outcome of the pending litigation.
EPA is encouraging all 48 contiguous states to begin working cooperatively in regional planning efforts to control regional haze. This work is likely to include (1) determining the regions of the country that would probably be subject to regional haze (visibility) and (2) developing State Implementation Plans to protect the 156 designated Class I areas (i.e., national parks).
The reduction in visibility is related to the formation of PM2.5 particulate matter and smog-generated aerosols. Accordingly, the regional haze rulemaking is highly interrelated to the NOx SIP Call, the Ozone NAAQS, the PM2.5 NAAQS, and the Section 126 Petitions. Actions taken with respect to one or more of these regulatory programs will have a benefit on regional haze. EPA has integrated regional haze considerations into the PM2.5 program.
The deciview (dv) scale, referred to in the Figure, is a visibility index that is analogous to the decibel scale for sound. The dv scale is approximately linear to humanly perceptible changes in visual air quality. A zero (0) dv value represents extremely good visibility. Increasingly higher dv values correspond to greater visibility impairment.
The New Source Review (NSR) program, which was established by the 1977 CAAA, requires all major new sources or substantially modified sources in both non-attainment areas and attainment areas to obtain permits. NSR permits are determined on a case-by-case basis by one of the ten EPA regional offices. Permitting application guidelines for attainment areas are covered by the Prevention of Significant Deterioration (PSD) program. Neither program covers hazardous air pollutants (HAPs).
The Clean Air Act requires the permitting of major new sources in non-attainment areas. To obtain a permit under the NSR program a facility must install control equipment ensuring the Lowest Achievable Emission Rate (LAER) and must demonstrate offsets of current pollutant emissions. With LAER, economic costs are not considered when defining the applicable control technology. LAER is defined as the more stringent of the following limitations:
- The most stringent emission limitation contained in a SIP of any state for the same class or category of source (unless it is demonstrated that this limitation is unachievable).
- The most stringent emission limitation achieved in practice.
Prevention of Significant Deterioration
Prior to the 1977 CAAA, the NAAQS only protected non-attainment areas. Virtually no restrictions were placed on facilities located in attainment areas. The Prevention of Significant Deterioration (PSD) program was introduced within the NSR program to address this issue.
The basic purpose of the PSD program is to maintain the air quality of the most pristine areas of the country and to allow a specified pollutant increase in other areas. A facility covered by the PSD program must take into account the level of air quality already attained in an area.
The PSD program is aimed at protecting Class I areas. Class I areas include national parks, national wilderness areas, national monuments, national seashores, and other areas of special national or regional natural, recreational, scenic, or historic value. Essentially no degradation of Class I areas is allowed under the PSD program. A decrease of emissions from one facility in a Class I area may be necessary for the permitting of a new facility. Facilities subject to the program include (1) existing major sources, (2) modified existing minor sources, and (3) new plants considered major sources, which contribute to the deterioration of air quality in Class I areas. These facilities must apply for a permit.
In order to obtain a permit a source must do the following:
- Evaluate the Best Available Control Technology (BACT). BACT
is based on the most stringent control available for a similar source
category that is technically and economically feasible.
- Perform an ambient air impact study, and
- Conduct additional impact studies including visibility, soils, and vegetation.
Class II areas include all attainment areas and unclassified areas that are not classified as either Class I or as industrialized attainment areas. A restricted increase over baseline levels is allowed in these areas. Industrialized attainment areas are classified as Class III and have less stringent allowable increases in emissions than Class I and Class II areas.
EPA has established incentives for companies through the Cap and Trade program. The Cap and Trade system rewards facilities by allowing them to sell their excess emission reductions to other facilities that require assistance in reducing emissions. In order to sell their emissions credits, facilities must either reduce their emissions before the deadline or achieve emission levels lower than required. The goal of the program is to allow companies to determine the most cost-effective method of meeting emission standards.
A Cap and Trade program is established for the Ozone Transport Commission (OTC) NOx emission trading program, the NOx SIP Call, and for SO2 trading by utility companies operating boilers subject to the 1990 CAAA Title IV acid rain requirements.
EPA is encouraging, but not requiring, states affected by the NOx SIP Call to participate in the NOx emissions Cap and Trade program. EPA has included incentives to sources that achieve early reductions of NOx from the 1999 ozone season through the 2002 ozone season. These emission reductions can be banked and used with certain restrictions during future ozone seasons.
For a facility to be eligible for emission trading, the emission reductions must go beyond regulatory requirements imposed by the Title IV acid rain (Phase II) requirements, the NOx SIP Call emission limits, and other related emission limitations.
Emission reductions must be quantifiable using continuous emission monitoring systems (CEMS) meeting Part 75 of the Acid Rain program requirements. Emission reductions must be verifiable through the use of adequate records and reports.
Within these limits, EPA proposes to permit the widest possible flexibility in emission trading and banking. Accordingly, it appears that sources will be allowed to trade emission allowances across state lines within a small number of zones. Furthermore, it should be possible to trade allowances between different classes of industrial sources included in the scope of the NOx SIP Call (i.e. from utility boilers to industrial boilers, or from cement kilns to gas turbines).
EPA has established a pool of credits to help ensure that the availability of electricity will not become a problem. States may issue credits if sources achieve their reduced emission levels before the deadline or if sources demonstrate a need for relief because they are not able to meet the compliance deadline.
Practice Problems
Title I - National Ambient Air Quality Standards
- Instructions:
- Complete the Practice Problems before proceeding to the next lesson. Click on the button below.