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Electronic Code of Federal Regulations

e-CFR Data is current as of January 22, 2015

Title 40Chapter ISubchapter CPart 51Subpart A → §51.50

Title 40: Protection of Environment
Subpart A—Air Emissions Reporting Requirements

§51.50   What definitions apply to this subpart?

Activity throughput means a measurable factor or parameter that relates directly or indirectly to the emissions of an air pollution source during the period for which emissions are reported. Depending on the type of source category, activity information may refer to the amount of fuel combusted, raw material processed, product manufactured, or material handled or processed. It may also refer to population, employment, or number of units. Activity throughput is typically the value that is multiplied against an emission factor to generate an emissions estimate.

Annual emissions means actual emissions for a plant, point, or process that are measured or calculated to represent a calendar year.

Ash content means inert residual portion of a fuel.

Contact name means the complete name of the lead contact person for the organization transmitting the data set, including first name, middle name or initial, and surname.

Contact phone number means the phone number for the contact name.

Control device type means the name of the type of control device (e.g., wet scrubber, flaring, or process change).

Day/wk in operations means days per week that the emitting process operates, averaged over the inventory period.

Design capacity means a measure of the size of a point source, based on the reported maximum continuous throughput or output capacity of the unit. For a boiler, design capacity is based on the reported maximum continuous steam flow, usually in units of million BTU per hour.

Emission factor means the ratio relating emissions of a specific pollutant to an activity or material throughput level.

Emission release point type means the code for physical configuration of the release point.

Emission type means the code describing temporal designation of emissions reported, i.e., Entire Period, Average Weekday, etc.

Exit gas flow rate means the numeric value of the flow rate of a stack gas.

Exit gas temperature means the numeric value of the temperature of an exit gas stream.

Exit gas velocity means the numeric value of the velocity of an exit gas stream.

Facility ID codes means the unique codes for a plant or facility treated as a point source, containing one or more pollutant-emitting units. The EPA's reporting format for a given inventory year may require several facility ID codes to ensure proper matching between databases, e.g., the state's own current and most recent facility ID codes, the EPA-assigned facility ID codes, and the ORIS (Department of Energy) ID code if applicable.

Fall throughput (percent) means the part of the throughput or activity attributable to the three fall months (September, October, November). This expresses part of the annual activity information based on four seasons—typically spring, summer, fall, and winter. It is a percentage of the annual activity (e.g., out of 600 units produced each year, 150 units are produced in the fall which is 25 percent of the annual activity).

FIPS Code. Federal Information Placement System (FIPS) means the system of unique numeric codes the government developed to identify states, counties and parishes for the entire United States, Puerto Rico, and Guam.

Heat content means the amount of thermal heat energy in a solid, liquid, or gaseous fuel, averaged over the period for which emissions are reported. Fuel heat content is typically expressed in units of Btu/lb of fuel, Btu/gal of fuel, joules/kg of fuel, etc.

Hr/day in operations means the hours per day that the emitting process operates averaged over the inventory period.

Inventory end date means the last day of the inventory period.

Inventory start date means the first day of the inventory period.

Inventory year means the year for which emissions estimates are calculated.

Lead (Pb) means lead as defined in 40 CFR 50.12. Lead should be reported as elemental lead and its compounds.

NAICS means North American Industry Classification System code. The NAICS codes are U.S. Department of Commerce's codes for businesses by products or services and have replaced Standard Industrial Classification codes.

Maximum nameplate capacity means a measure of the size of a generator which is put on the unit's nameplate by the manufacturer. The data element is reported in megawatts or kilowatts.

Method accuracy description (MAD) codes means a set of six codes used to define the accuracy of latitude/longitude data for point sources. The six codes and their definitions are:

(1) Coordinate Data Source Code: The code that represents the party responsible for providing the latitude/longitude.

(2) Horizontal Collection Method Code: Method used to determine the latitude/longitude coordinates for a point on the earth.

(3) Horizontal Accuracy Measure: The measure of accuracy (in meters) of the latitude/longitude coordinates.

(4) Horizontal Reference Datum Code: Code that represents the reference datum used to determine the latitude/longitude coordinates.

(5) Reference Point Code: The code that represents the place for which geographic coordinates were established. Code value should be 106 (e.g., point where substance is released).

(6) Source Map Scale Number: The number that represents the proportional distance on the ground for one unit of measure on the map or photo.

Mobile source means a motor vehicle, nonroad engine or nonroad vehicle, where:

(1) A motor vehicle is any self-propelled vehicle used to carry people or property on a street or highway;

(2) A nonroad engine is an internal combustion engine (including fuel system) that is not used in a motor vehicle or a vehicle used solely for competition, or that is not affected by sections 111 or 202 of the CAA; and

(3) A nonroad vehicle is a vehicle that is run by a nonroad engine and that is not a motor vehicle or a vehicle used solely for competition.

Nitrogen oxides (NOX) means nitrogen oxides (NOX) as defined in 40 CFR 60.2 as all oxides of nitrogen except N2O. Nitrogen oxides should be reported on an equivalent molecular weight basis as nitrogen dioxide (NO2).

Nonpoint sources. Nonpoint sources collectively represent individual sources that have not been inventoried as specific point or mobile sources. These individual sources treated collectively as nonpoint sources are typically too small, numerous, or difficult to inventory using the methods for the other classes of sources.

Ozone season means the period from May 1 through September 30 of a year.

Particulate Matter (PM). Particulate matter is a criteria air pollutant. For the purpose of this subpart, the following definitions apply:

(1) Filterable PM2.5 or Filterable PM10: Particles that are directly emitted by a source as a solid or liquid at stack or release conditions and captured on the filter of a stack test train. Filterable PM2.5 is particulate matter with an aerodynamic diameter equal to or less than 2.5 micrometers. Filterable PM10 is particulate matter with an aerodynamic diameter equal to or less than 10 micrometers.

(2) Condensable PM: Material that is vapor phase at stack conditions, but which condenses and/or reacts upon cooling and dilution in the ambient air to form solid or liquid PM immediately after discharge from the stack. Note that all condensable PM, if present from a source, is typically in the PM2.5 size fraction, and therefore all of it is a component of both primary PM2.5 and primary PM10.

(3) Primary PM2.5: The sum of filterable PM2.5 and condensable PM.

(4) Primary PM10: The sum of filterable PM10 and condensable PM.

(5) Secondary PM: Particles that form or grow in mass through chemical reactions in the ambient air well after dilution and condensation have occurred. Secondary PM is usually formed at some distance downwind from the source. Secondary PM should not be reported in the emission inventory and is not covered by this subpart.

Physical address means the street address of a facility. This is the address of the location where the emissions occur; not, for example, the corporate headquarters.

Point source means large, stationary (nonmobile), identifiable sources of emissions that release pollutants into the atmosphere. A point source is a facility that is a major source under 40 CFR part 70 for the pollutants for which reporting is required, except for the emissions of hazardous air pollutants, which are not considered in determining whether a source is a point source under this subpart. The minimum point source reporting thresholds in tons per year of pollutant are as follows, as measured in potential to emit:

Pollutant Annual cycle
(Type A sources)
Three-year cycle
Type B sources1 NAA sources2
(1) SOX2500100100.
(2) VOC250100O3 (moderate) 100.
(3) VOCO3 (serious) 50.
(4) VOCO3 (severe) 25.
(5) VOCO3 (extreme) 10.
(6) NOX 2500 100 100.
(7) CO 25001000O3 (all areas) 100.
(8) COCO (all areas) 100.
(9) Pb 5 5.
(10) PM10 250 100PM10 (moderate) 100.
(11) PM10PM10 (serious) 70.
(12) PM2.5 250 100 100.
(13) NH3 250 100 100.

1Type A sources are a subset of the Type B sources and are the larger emitting sources by pollutant.

2NAA = Nonattainment Area. Special point source reporting thresholds apply for certain pollutants by type of nonattainment area. The pollutants by nonattainment area are: Ozone: VOC, NOX, CO; CO: CO; PM10: PM10.

Pollutant code means a unique code for each reported pollutant assigned by the reporting format specified by EPA for each inventory year.

Primary capture and control efficiencies means two values indicating the emissions capture efficiency and the emission reduction efficiency of a primary control device. Capture and control efficiencies are usually expressed as a percentage.

Process ID code means a unique code for the process generating the emissions, typically a description of a process.

Roadway class means a classification system developed by the Federal Highway Administration that defines all public roadways as to type based on land use and physical characteristics of the roadway.

Rule effectiveness (RE) means a rating of how well a regulatory program achieves all possible emissions reductions. This rating reflects the assumption that controls typically are not 100 percent effective because of equipment downtime, upsets, decreases in control efficiencies, and other deficiencies in emission estimates. Rule effectiveness adjusts the control efficiency from what could be realized under ideal conditions to what is actually emitted in practice due to less than ideal conditions.

Rule penetration means the percentage of a nonpoint source category covered by an applicable regulation.

SCC means source classification code, a process-level code that describes the equipment and/or operation which is emitting pollutants.

Site name means the name of the facility.

Spring throughput (percent) means part of the throughput or activity attributable to the three Spring months (March, April, May). See also the definition of Fall throughput.

Stack diameter means the inner physical diameter of a stack.

Stack height means physical height of a stack above the surrounding terrain.

Stack ID code means a unique code for the point where emissions from one or more processes release into the atmosphere.

Sulfur content means the sulfur content of a fuel, usually expressed as percent by weight.

Summer day emissions means an average day's emissions for a typical summer work weekday. The state will select the particular month(s) in summer and the day(s) in the work week to be represented. The selection of conditions should be coordinated with the conditions assumed in the development of reasonable further progress (RFP) plans, rate of progress plans and demonstrations, and/or emissions budgets for transportation conformity, to allow comparability of daily emission estimates.

Summer throughput (percent) means the part of throughput or activity attributable to the three Summer months (June, July, August). See also the definition of Fall throughput.

Total capture and control efficiency (percent) means the net emission reduction efficiency of all emissions collection devices.

Type A source means large point sources with actual annual emissions greater than or equal to any of the emission thresholds listed in Table 1 of Appendix A of this subpart for Type A sources. If a source is a Type A source for any pollutant listed in Table 1, then the emissions for all Table 1 pollutants must be reported for that source.

Unit ID code means a unique code for the unit of generation of emissions, typically a physical piece of or a closely related set of equipment. The EPA's reporting format for a given inventory year may require multiple unit ID codes to ensure proper matching between databases, e.g., the state's own current and most recent unit ID codes, the EPA-assigned unit ID codes if any, and the ORIS (Department of Energy) ID code if applicable.

VMT by SCC means vehicle miles traveled disaggregated to the SCC level, i.e., reflecting combinations of vehicle type and roadway class. Vehicle miles traveled expresses vehicle activity and is used with emission factors. The emission factors are usually expressed in terms of grams per mile of travel. Because VMT does not correlate directly to emissions that occur while the vehicle is not moving, nonmoving emissions are incorporated into the emission factors in EPA's MOBILE Model.

VOC means volatile organic compounds. The EPA's regulatory definition of VOC is in 40 CFR 51.100.

Winter throughput (percent) means the part of throughput or activity attributable to the three winter months (January, February, December of the same year, e.g., winter 2005 is composed of January 2005, February 2005, and December 2005). See also the definition of Fall throughput.

Wk/yr in operation means weeks per year that the emitting process operates.

Work weekday means any day of the week except Saturday or Sunday.

X stack coordinate (longitude) means an object's east-west geographical coordinate.

Y stack coordinate (latitude) means an object's north-south geographical coordinate.

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