Prevention of Significant Deterioration


Prevention of Significant Deteriorationsearch for term

A regulatory program based not on the absolute levels of air pollution allowable in the atmosphere but on the amount by which a legally defined baseline condition will be allowed to deteriorate in a given area. Under this program, geographic areas are divided into three classes, each allowing different increases in nitrogen dioxide, particulate matteri, and sulfur dioxide concentrations. Prevention of significant deteriorationi above legally established levels includes the following, used to classify a region:

  • Class I—minimal additional deterioration in air quality (certain national parks and wilderness areas).
  • Class II—moderate additional deterioration in air quality (most lands).
  • Class III—greater deterioration for planned maximum growth (industrial areas).