EIF-2-Video_EI_Overview
This module provides a brief overview on emission inventories (EIs). Learning objectives for this session:

Know the definition of emission inventory (EI).

Know the most common reasons for completing an EI for Native American Reservations.

Know the different levels of EIs.

Know the basic source types included in EI.

Know the pollutants commonly included in EIs.

Describe the general process for completing an EI.
What is an emission inventory?
An EI is a listing, by source, of air pollutant emissions associated with a specific geographic area for a specific time interval.
Why should a Tribe complete an EI? What are EIs used for?
Although all states are required by the Clean Air Act (CAA) to complete emissions inventories on a regular basis, EIs are not required under law for Native American Reservations. Tribes usually complete
EIs for their reservations for the following reasons:

The EI is a fundamental building block in developing an air quality control and maintenance strategy. When a tribe has a concern with the quality of their air, or wishes to protect the good quality of their air, they often take steps to start a tribal air program. It is difficult to plan and implement a successful air quality program without the benefit of a good inventory. If a tribe gets a CAA grant to start an air quality program, it is often required to complete an EI under their grant from EPA. If a tribe does not have a CAA grant, but wants to apply for one, they can complete an
EI to show that they have a need for a CAA grant.

An EI provides baseline data for the year it is completed. Future updates to the EI can show how new industries or developments on the reservation have affected air quality.

Emissions estimates developed through an EI can be used to predict pollutant concentrations in the ambient air through the use of dispersion modeling.
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EI data can serve as the basis for developing and implementing minor source and construction permitting programs.
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EI data can provide input for human health risk assessment studies.
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EI data can be used to determine the need for ambient air monitors and to site monitors.
Pollutants Covered in EIs.
EIs usually include sources of criteria pollutants at a minimum. Many EIs also contain sources of HAPs or air toxics. The TEISS calculators estimate HAP emissions for many source types. HAPs are reported to

EPA on a voluntary basis, but reporting is encouraged.
Criteria pollutants are the most common air pollutants. EPA regulates criteria pollutants based on healthbased criteria and sets standards.
 Primary standard - If pollutant is below, health is protected. List examples.
 Secondary standard - If pollutant is above, environmental and property damage can occur.
Criteria Air Pollutants (CAPs)
Particulate Matter - PM10 and PM2.5
Nitrogen Oxides - NOx
Sulfur Dioxide - SO2
Carbon Monoxide - CO
Lead - Pb
Ammonia - NH3
Volatile Organic Compounds – VOC
About ozone – Ozone isn’t directly emitted by sources. VOCs and NOx react with sunlight to form ozone.
Therefore, NOx and VOC are inventoried, but not ozone itself.
Hazardous Air Pollutants (HAPs)
Cause serious health and environmental hazards
 Cancer, birth defects, death, serious illness
 Kills or seriously harms vegetation, animals, fish
There are 187 HAP compounds listed in the Clean Air Act.
Some examples of HAPs, with their typical sources shown in parentheses, are listed below:
 Mercury (Power plants, coal-fired)
 Perchloroethlyene (Dry Cleaning)
 Benzene (Gasoline)
 Chloroform (chlorination plants, paper mills)
 Methyl Isocyanate (pesticide manufacturing) o A release at Bhopal, India killed 4,000 people
 The list goes on…….
For more information on HAPs:
Health Effects Notebook for HAPS: www.epa.gov/ttn/atw/hlthef/hapindex.html
EPA divides the sources of air pollution that agencies should report data for into five general categories: Point, Nonpoint, On-Road Mobile, Non-Road Mobile and Events. List one example for each.

Airports tricky here. Airplanes used to be considered as non-road sources. Starting with the 2008 NEI, all airports, and the planes that take-off and land at them, are considered point sources. If you have airports on your reservation, check the most recent NEI data. Use it in your EI unless you have more accurate data. Prior to the inventory reporting period, EPA posts the Landing and Takeoff activity data. These data are down to mom and pap airstrips and helio pads. These are the activity data which EPA will use in the NEI unless updated data are received from the Tribes. These data are from the FAA and sometimes can be overestimated.
Commercial marine vessels and locomotives are reported as nonpoint sources.
SLIDE 9: Inventory Steps
1. Identify sources through NEI data, and use ITEP’s downloaded NEI data as an import into TEISS
2. Use TEISS to understand and map the emissions and sources
3. Apply quality assurance/quality control (QA/QC) procedures —even if only using existing data, you must document all of your steps in a dedicated EI logbook, and you may have to submit a
QAPP even for a level 4 inventory, as specified by your project officer (ITEP has a mock QAPP for a level 4 inventory, as well as examples of QAPPs for levels 1-3 Inventories that you can use as a starting point).
4. Write a summary report on the results organized in TEISS (use TEISS maps and tables) that you can submit to tribal council, the community, and your EPA project officer.
Emissions sources are broadly classified into several categories.

Point sources, like huge coal fired power plants, but also can include activities such as gravel mining.
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Nonpoint sources, which can include dust (particulate matter) from dirt roads, or wood smoke from chimneys/open fires, or clumps of gas stations.
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Event sources, currently includes wildfires and prescribed burns sources.
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Mobile sources both On-Road and Non-Road, mostly cover the exhaust emitted from the use of fossil fuels in internal combustion engines. On-road includes street legal vehicles, like cars, busses, trucks, etc. Non-Road includes tractors, snowmobiles, and of course the local lawnmower races.
 Biogenic emissions are those ‘natural’ emissions from plants and soils.
Stay tuned for specifics on each of these.
Point Sources
Stationary sources of emissions identified individually in the inventory. These are usually large sources, such as manufacturing plants, power plants, refineries, and industrial facilities. A point source can have emissions from smoke stacks, units directed to stacks, and fugitive sources within the facility.
Point sources may have a minimum reporting threshold; that is, sources emitting above a certain amount of pollution must be included as point sources in the EI. Thresholds can be based on level of emissions, potential emissions, type of source, toxicity of the pollutant, and/or that location’s non-attainment area classification.

 EPA's Part 40 CFR Part 51 Air Emissions Reporting Requirements (AERR) requires that sources
 above certain annual emissions thresholds be reported as point sources.
In addition, many states also inventory and report stationary sources below these thresholds as
 point sources. Just as some states have done, your tribe can choose to report point sources with annual emissions lower than the values in the table.
It’s recommended you find out what the states surrounding you use for point source reporting thresholds. Consider using the state’s thresholds to define point sources on your reservation. By doing this you help ensure your tribe’s inventory is compatible with the inventories of the areas surrounding you.
To give an example of how states’ thresholds can be different from those in the AERR, the following table shows New Mexico’s reporting thresholds compared to the AERR’s thresholds for areas in attainment.
Pollutant EPA’s AERR Reporting
Thresholds (tons per year)
New Mexico Environment
Department Reporting
Thresholds (tons per year)
Lead (Pb)
Particulate Matter less than 10 microns (PM10)
PM2.5
≥0.5
≥100
>1
>10
>10
Nitrogen Oxides (NOx)
Carbon Monoxide (CO)
≥100
≥100
≥1000
≥100
>10
>10
>10 Volatile Organic Compounds
(VOC)
Ammonia (NH3) ≥100 No minimum threshold specified.
As you can see, in this case, the state’s reporting thresholds are much lower than the AERR’s. By using the state’s thresholds for your reservation’s inventory, you would get a more detailed listing of the point sources of pollution. For example, a busy gas station on a state highway would likely be considered a point source in New Mexico. If you were following the AERR, a gas station would not be considered a point source and would instead be inventoried as a nonpoint source.
 Point sources are defined for air toxics, also known as hazardous air pollutants (HAPs) as sources that emit 10 tons per year of any of the listed toxic air pollutants, or 25 tons per year of a mixture of air toxics. These sources may release air toxics from equipment leaks, when materials are transferred from one location to another, or during discharge through emission stacks or vents.
Nonpoint (Area) Sources
Facilities or activities whose individual emissions do not qualify them as point sources. Nonpoint sources represent numerous facilities or activities that individually release small amounts of a given pollutant, but collectively they can release significant amounts of a pollutant. For example, a single homes woodstove

emissions will not qualify as a point source, but collectively the emissions from all of the woodstoves in the inventory area may be significant; thus they must be included in the inventory as a nonpoint source. If your gas stations are all small operations, or you chose to use the AERR reporting thresholds, the reservations gas stations could be lumped together as a nonpoint source. Sources that are spread across a large area can also be nonpoint sources. The dust that comes off of unpaved roads or off of agricultural fields during tilling and harvest are examples.
Events
Includes significant, reportable air emissions resulting from short-term events. Wildfires and controlled burns can be classified as events, as well as other natural and human caused disasters. To be classified as an event in the NEI, temporal characteristics (date/time of event period) and spatial characteristics
(coordinate values) must be reported.
On-Road Mobile Sources
Includes all vehicles that operate on roads such as automobiles, light trucks, heavy-duty trucks, buses, and motorcycles.
Non-Road Mobile Sources
Includes vehicles and machinery that operate off of roads, such as farm and construction equipment, marine engines, recreational equipment and lawn mowers.
Exceptions: Airplanes used to be considered as non-road sources. Starting with the 2008 NEI, all airports, and the planes that take-off and land at them, are considered point sources. If you have airports on your reservation, check the most recent NEI data. Use it in your EI unless you have more accurate data.
Commercial marine vessels and locomotives are reported as nonpoint sources.
Biogenic Sources
Naturally occurring emissions. Can be from vegetation or microbial (soil, bacteria, termites, etc.). EPA estimates these emissions on the county level for the U.S. If interested in including biogenic emissions in your EI, obtain the county level emissions.
Source Examples
Q: Point, Nonpoint, Non-road Mobile, On-Road Mobile or
Event?
A. Point Source
This is the Navajo Power Generating Station on the
Navajo Reservation. It is a large coal-fired power plant. Its size, large stacks and the amount of pollution it produces make it a point source.

Q: Point, Nonpoint, Non-road Mobile, On-Road Mobile or
Event?
A. Point or Nonpoint Source (There are a couple on-road mobile sources in there too!)
Gas station can be considered either a point or a nonpoint source. For many gas stations, their size and the amount of pollution they produce would classify them as Nonpoint sources. However, some tribes have just 1-5 gas stations on their reservation and it is easy to collect gasoline sales data from each one, so they classify them as Point sources. States vary in how they treat gas stations in their inventories, some treat them as nonpoint sources, others as point sources. For your reservation, it is up to you. If you can collect gasoline sales data from every station on your reservation, treat them as point sources. If you have many gas stations, treat them as nonpoint sources.
Q: Point, Nonpoint, Non-road Mobile, On-Road Mobile or
Event?
A. Nonpoint Source
Wood smoke from homes is a nonpoint source. Each home produces only a small amount pollution, but when all the homes of a community or the reservation are added together, it becomes more significant and should be part of your inventory as a nonpoint source. If people burn fuel oil or propane to heat their homes, each of those should be treated as a separate nonpoint source.
Q: Point, Nonpoint, Non-road Mobile, On-Road Mobile or
Event?
A. Point Source and a Non-Road Mobile Source
This gravel pit looks large enough that it could be considered a point source for particulate matter. If you have many small gravel operations on your reservations, you could lump them together as a nonpoint source. The bulldozer is a non-road mobile source. If you inventoried your gravel pit as a point source, you would include the non-road mobile sources as processes that occur within the point source.

Q: Point, Nonpoint, Non-road Mobile, On-Road Mobile or
Event?
A. On-Road Mobile and Nonpoint Source
This picture shows two sources. The truck is an on-road mobile source. The dust coming up off the road is a nonpoint source.
Q: Point, Nonpoint, Non-road Mobile, On-Road Mobile or
Event?
A. Non-Road Mobile Source
Because they do not usually travel on regular roads, but on snow-covered trails, snowmobiles are considered Nonroad mobile sources.
Q: Point, Nonpoint, Non-road Mobile, On-Road Mobile or
Event?
A. Nonpoint Source
Burning of agricultural field stubble can be spread over a large area so it is considered a nonpoint source.
Q: Point, Nonpoint, Non-road Mobile, On-Road Mobile or
Event?
A. Nonpoint Source
Oil and gas wells do not release much pollution individually, but many wells together in an oil or gas field can release significant amounts of pollution, classifying them as nonpoint sources.

Think about what level your EI is going to be and email the answer to the instructors, using the questionnaire below. If, as you go through the modules, you decide to change the level of your EI, that is fine, but please let your instructors know this.
1. Based on information you already know about your land, what sources are there that you already know about? (QAPP NOTE: This can be the start of your source list to include in your QAPP.)
2. Using the MyReservationEI as an example, write your Introduction, Location, and
Emissions Area sections
3. Email these three sections to your instructor