About the Facility MACT Report - Hazardous Air Pollutants

What does the report tell me?

The Facility MACT Report summarizes hazardous air pollutant (HAP) emissions by type of industry or commercial activity. For this report, sources are grouped by the type of HAP emission control regulations that apply, which are called Maximum Achievable Control Technology (MACT). EPA's Air Toxics Web site has more information on MACT source categories and the MACT program, which has brought about significant reductions in HAP emissions. (www.epa.gov/ttn/atw/eparules.html)

The MACT Report includes all stationary sources that are subject to MACT regulations and emit any of the HAPs that you specify, grouped by MACT category. For each category, the report gives, for each selected HAP, the total estimated annual emissions and subtotals for point and nonpoint sources. Point sources are facilities (both "major" and "area") for which EPA's National Emission Inventory (NEI) database has individual HAP emission estimates. Nonpoint sources are stationary sources whose individual locations are not recorded, and for which the NEI database has county aggregate emission estimates.

Each row of the MACT Report displays information for a MACT category and year within a geographic area (county, state, or EPA region). In other words, the MACT categories are listed separately, by year, for each geographic area. A row of the report includes MACT category description, number of HAP point sources (facilities) in the category, total estimated annual emissions of each HAP you selected, and subtotal emissions from point and nonpoint sources. The Grand Total line at the bottom of each report page shows the totals of these items for all sources included in the report.

The National Emissions Inventory (NEI) is an emission inventory developed every three years (1999, 2002, etc.) by EPA. The NEI is a national inventory of stationary and mobile sources that emit hazardous air pollutants (HAPs). HAPs are generally defined as those pollutants that are known or suspected to cause serious health problems. Section 112(b) of the Clean Air Act currently identifies a list of 188 pollutants as HAPs. The NEI contains emission estimates for major sources, nonpoint sources, mobile sources, and other sources which do not readily fall into these categories. Point sources in the NEI are sources for which the specific location is known; they may be either major or area sources. As best as possible, point sources in the NEI have each been identified as either major or area, but this identification may not correspond to the official regulatory classification of some sources. Nonpoint sources in the NEI include area sources that are not identified as point sources because their specific locations are not known. Nonpoint sources also include other sources such as wildfires and prescribed burning whose emissions are estimated at the county level.

What does the report look like?

The example report shows emissions of two HAPs summarized by county and MACT category. A report row gives the emissions from sources in one county that are in a particular MACT category. There are three emissions columns for each HAP: the total, and subtotals for point and nonpoint sources. The red up-arrow button in the county column indicates that report rows are in ascending alphabetical order by county name. (MACT category is a secondary sort order.)

How can I customize the report?

Sort Order

You can use the SORT buttons in each report column to change the order of rows in the report. The default sort order is descending total HAP emissions, which puts MACT categories with higher emissions at the beginning of the report and categories with lower emissions at the end.

Detail or Summary

This is always a summary report. Although a row of the report always presents data for a single MACT category, omitting optional report columns can change the level of summarization. In a default report, with the County column included, a row of the report summarizes MACT category within county. The report has a row for every combination of county and MACT category. A row gives the county total emissions for a particular MACT category.

If you omit the County and County Code columns, a row of the report summarizes MACT categories by state. The report has a row for every combination of MACT category and state. A row gives the state total emissions for a MACT category.

If you also omit the State column, the report summarizes MACT category HAP emissions by EPA region. If you also omit the EPA Region column, the report gives total HAP emissions for each MACT category within the entire geographic scope of the report (national totals, for example).

Individual Pollutants or Total Emissions

You may have the report display the emissions of one to six separate HAPs, the total emissions of urban HAPs (Sum of 33 urban HAPs), or the total emissions of all HAPs (Sum of 188 HAPs). If you select specific HAPs, the report includes facilities emitting at least one of those HAPs. If you select Sum of 33 urban HAPs, the report includes facilities that emit one or more of the 33 urban HAPs. If you select Sum of 188 HAPs, the report includes facilities that emit any of the 188 HAPs.

If you choose Sum of 188 HAPs in combination with individual HAPs, the report includes facilities that emit any of the 188 HAPs. If you choose Sum of 33 urban HAPs in combination with individual HAPs, the report includes facilities that emit any urban HAP and facilities that emit any individual HAP selected.

Format of Emissions Values

Depending on the Pollutant Emissions Format option that you choose for the report, emission values are displayed as decimal numbers (0.0351) or in scientific notation (3.51E-02). With the decimal option in effect, values smaller than 0.0001 are displayed as "< 0.0001" in an html report and displayed in scientific notation when exporting to a text file.

What do the report columns mean?

Row #: Sequence number of report rows (lines). Sequence numbers are not associated with particular rows; they simply enumerate the rows of a report from first to last. Thus, choosing an alternate sort order for a report would change the sequence numbers associated with particular rows.
EPA Region: EPA region number in which a source is located. There are ten EPA regions. [ Details ]
State: Postal abbreviation for the state or territory in which a source is located. [ Details ]
County: Name of the county (or equivalent jurisdiction) in which a source is located.
County Code: Code for the county (or equivalent jurisdiction) in which a source is located, consisting of 2-digit FIPS state code and 3-digit FIPS county code. FIPS is the acronym for Federal Information Processing Standards, which defines codes used in most U.S. government information systems.
Urban/Rural Designation: (This column is included in the report only if County or County Code also is included.) For purposes of developing EPA's Integrated Urban Air Toxics Strategy, a county was considered "urban" if either:
1) it includes a metropolitan statistical area with a population greater than 250,000; or
2) the U.S. Census Bureau designates more than fifty percent of the population as "urban."
The Integrated Urban Air Toxics Strategy is an important part of EPA's national air toxics program. Please note that the definition of "urban" does not necessarily apply for regulatory or implementation purposes. (www.epa.gov/ttn/atw/urban/urbanpg.html)
MACT Category: Code number and description of a category of HAP sources for which emissions limitations have been or are being developed under Section 112(d) of the Clean Air Act (National Emissions Standards for Hazardous Air Pollutants).

EPA sets source category standards through its MACT program. These technology based rules sharply reduce HAP emissions. EPA's air toxics web site includes information on MACT source categories and the MACT program. (www.epa.gov/ttn/atw/eparules.html)
Number of Point Sources: Number of point sources (facilities) within the MACT category represented by a row of the report. The report includes all point sources (major and area) in the NEI database that are subject to MACT regulations, regardless of their emission levels.

If you selected multiple HAPs, the report lists largest number of point sources among them.
Total Emissions
Point Source Emissions
Nonpoint Source Emissions: Estimated annual HAP emissions, in pounds, from all stationary sources within the MACT category, geographic entity, and year represented by a row of the report.

If you selected multiple HAPs, the report includes an emissions column for each of them, and displays pollutant name in the column heading. See the NEI HAP Names table for alternative pollutant names and identification codes.

Total Emissions is the sum of Point Source and Nonpoint Source emissions. The Point Source subtotal includes all point sources (major and area) in the NEI database, regardless of their emission levels. The Nonpoint Source subtotal includes area sources (stationary sources whose locations are not recorded), but not mobile sources or "other" sources, such as wildfires.

An emission estimate is based on the normal operating schedule of a source, and includes the effects of installed pollution control equipment and regulatory restrictions on operating conditions.
% Of Grand Total
% Of Point Total
% Of Nonpoint Total: Fraction (percentage) of the report's Grand Total emissions attributable to the MACT category and geographic area represented by a row of the report.