^aIf the generators of a particular vintage (or in a particular NSPS category) emitted a particular pollutant in proportion to its share of total electricity generation, the value would be 1.

^bCapacity factor of units that operated that are strictly associated with boilers in CEMS database.

^cThe Subpart D standards are those that apply to fossil-fuel-fired steam boilers for which construction began after August 17, 1971. The Subpart Da standards affect those boilers that began construction after September 18, 1978. For those boilers not covered by NSPS construction commenced before August 17, 1971. Notes: All quantities, including percentages of emissions and generation capacity, are calculated with reference only to coal-fired generating units. Percentages (taking account of rounding) add to 100% because other types of generating capacity are not considered.

These tables and the associated data set were constructed by David Evans of Resources for the Future. Data used to make these tables come from three sources; emissions data are from EPA’s Continuous Emissions Monitoring System Database; generation and capacity data are from the EIA’s 767 data set; and information on vintage of generating units is from the EIA's 860 data set. Abbreviations: EIA, Energy Information Agency; Btu/kWh, British thermal unit per kilowatt-hour; lb/MWh, pound per megawatt-hour.

Source: EIA 2004a,b; EPA 2004p.