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Homepage » Lesson 1 » Lesson 1.4
EPA divides the sources of air pollution into 4 general categories: Point, Nonpoint (called Area in TEISS), On-Road Mobile and Non-Road Mobile.
Point Sources
Stationary sources of emissions identified individually in the inventory.
Point sources may have a minimum reporting threshold; that is, sources emitting above a certain level must be included as point sources in the inventory. Thresholds can be based on level of emissions, potential emissions, type of source, or toxicity of the pollutant.
- For criteria pollutants , the emission thresholds vary according to the attainment status and classification of the area in which the source is located, as shown in the table below. Any stationary source emitting pollutants at levels equal to or greater than those shown in the table below must be inventoried and 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.
EPA's Consolidated Emissions Reporting Rule (CERR) requires that sources above certain emissions thresholds be reported as point sources. The CERR thresholds are:
MINIMUM POINT SOURCE REPORTING THRESHOLDS BY POLLUTANT
In tons per year
| Pollutant |
Attainment Area Threshold |
Non-Attainment Area Thresholds |
| SOx |
>100 |
>100 |
| VOC |
>100 |
Moderate O3: >100
Serious O3: >50
Severe O3: >25
Extreme O3 >10 |
| NOx |
>100 |
>100 |
| CO |
>1000 |
O3 (all areas): >100
CO (all areas): >100 |
| Lead - Pb |
>5 |
>5 |
| PM10 |
>100 |
Moderate PM10: >100
Serious PM10: >70 |
| PM 2.5 |
>100 |
>100 |
| Ammonia - NH3 |
>100 |
>100 |
- Point sources are defined for 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 dry cleaner within an inventory area typically will not qualify as a point source, but collectively the emissions from all of the dry cleaning facilities in the inventory area may be significant; thus they must be included in the inventory as an area 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.
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 all vehicles and machinery that move off of roads, such as airplanes, trains, farm and construction equipment, marine engines, recreational equipment and lawn mowers.
 ONLINE Exercise: What kind of a source is it?
Pollutants Covered in EIs:
EIs usually include sources of criteria pollutants at a minimum. Many EIs also contain sources of HAPs or air toxics. TEISS supplies estimates of HAP emissions for many types of emissions sources.
Criteria pollutants are the most common air pollutants. EPA regulates criteria pollutants based on health-based criteria and sets standards.
- Primary standard - If pollutant is below, health is protected
- Secondary standard - If pollutant is above, environmental and property damage can occur.
Criteria Air Pollutants (CAPs)
Nitrogen Oxides - NOx
Sulfur Dioxide - SO2
Carbon Monoxide - CO
Ammonia - NH3
Particle Matter - PM10 and PM2.5
Volatile Organic Compounds - VOC
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 188 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)
- Perchlorethlyene (Dry Cleaning)
- Benzene (Gasoline)
- Chloroform (chlorination plants, paper mills)
- Methyl Isocyanate (pesticide manufacturing)
- A release at Bhopal, India killed 4,000 people
- 1,2,3,4,6,7,8 Heptachlorodibenzofuran ?!
- The list goes on…….
For more information on HAPs:
Health Effects Notebook for HAPS: www.epa.gov/ttn/atw/hlthef/hapindex.html
End of Lesson 1.4
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