Clean Air Act Amendments of 1977 and Prevention of Significant Deterioration

By 1977, most areas of the country had still not attained the NAAQSs for at least one pollutant [4]. For those areas that had not attained a NAAQS (i.e., nonattainment areas), states were required to submit and have an approved state implementation plan (SIP) revision by July 1, 1979, that demonstrated how attainment would be achieved by December 31, 1982. This requirement was a precondition for the construction or modification of major emission sources in nonattainment areas after June 30, 1979. If a state could not attain primary standards for carbon monoxide or photochemical oxidants after implementation of all reasonably available measures, it was required to submit a second SIP revision by December 31, 1982, that would demonstrate how attainment would be achieved by December 31, 1987.

Prevention of Significant Deterioration

The concern over nonattainment areas and the controversy generated by the provision in the 1970 Clean Air Act Amendments on standards preventing continuing deterioration of air quality led to a set of guidelines issued in 1974 by the EPA to prevent the significant deterioration of air quality in areas that were cleaner than required by NAAQS (i.e., had attained the NAAQSs). This was necessary because some interpreted the 1970 act to mean that a region could not backslide in air quality even though the current air quality may be superior to the national standard. This interpretation would have stifled economic growth in a region (new industrial and commercial operations in the region could not contribute zero pollution), and would have failed to force sources in the region to decrease their contaminant emissions. This concern led to the passage of regulations regarding the prevention of significant deterioration (PSD). The PSD regulations for attainment areas required that all of these areas be designated as Class I, II, or III, depending upon the degree of deterioration to be allowed, and incremental limits were placed on the amount of increase in deterioration allowed. The classifications are [4]:

• Class I—Pristine areas, including international parks, national parks, and national wilderness areas in which very little deterioration would be allowed;

• Class II—Areas where moderate change would be allowed, but where stringent air quality constraints are desirable;

• Class III—Areas where major growth and industrialization would be allowed.

Congress specified which of the areas must be protected by the most stringent Class I designation, designated all other areas within the United States as Class II areas, and provided the option for redesignation of Class II areas to Class I or Class III areas by public referendum. Congress also specified the maximum allowable incremental increases in concentration of sulfur dioxide and particulate matter and charged the EPA to determine comparable increments for hydrocarbons, carbon monoxide, photochemical oxidants, and nitrogen oxides. The PSD increments are listed in Table 4-2 [4].

A requirement was placed on major sources in the preconstruction PSD review process that specified that each major new plant must install BACT, which was defined to be at least as stringent as NSPS, to limit its emissions. Major sources subject to PSD review are those with the potential to emit 100 short tons or more per year of any regulated pollutant under the Clean Air Act Amendment of 1977 [4]. All sources emitting greater than 250 short tons

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