How are allowable emissions calculated?
Allowable emissions can be set by many methods. The two most common are by regulation or by permit condition. In general, allowable emissions are calculated by taking the allowable emission rates for each emission unit in pounds/hour multiplied by the allowable hours of operation divided by 2000 pounds/ton. The values for all emission units are then summed to obtain the plant total. If the emission unit does not have a restriction on the number of hours it can operate, the maximum hours of operation indicated in your permit application are used. If there is no limitation on your emissions (NOx emissions from small gas-fired boilers for example), your maximum emission rate is substituted for allowable.
