Maximum Allowable Increase
Particulate Matter (TSP)
Annual geometric mean
The maximum allowable concentration resulting from an applicable increment
will not be allowed to exceed a national primary or secondary ambient air quality
The three classes have been established to allow flexibility in new source
permitting. Most of the United States is classified as Class II. There are no Class
III areas in the country. A Class III area would allow the largest amount of new
pollution. The most stringent classification is Class I. These areas are principally
international parks and large national wilderness areas, large national parks, and large
national memorial parks. If the facility is located within a Class II area, the Class I
increments must still be met at the boundaries of any nearby Class I area.
All new sources since an established "baseline date" will use up available
increment. Old sources which shut down will make more increment available. The amount
of increment available to a proposed new source must be calculated as part of the
permitting process. Again modeling is used for the calculations. Just as in the NAAQS,
the amount of increment available to a new source may affect the amount of stack
emissions which can be permitted.
concentrations in the flue gas emissions. They vary depending on the fuel to be burned.
The Federal NSPS have been established for three categories of fossil fuel steam power
plants as follows:
a) 40 CFR Part 60, Subpart D, Standards of Performance for Fossil Fuel
Fired Steam Generators for Which Construction is Commenced After August 17, 1971.
b) 40 CFR Part 60, Subpart Da, Standards of Performance for Electric
Utility Steam Generating Units for Which Construction is Commenced After September 18,