# Presentation: 663523

## Preparation of Fine Particulate Emissions Inventories 

***Preparation of Fine Particulate Emissions Inventories ***

**Chapter 5 – Point Source Inventory Development**

**Notes:**
After completing this lesson, participants will be able to:
identify point sources for inclusion in an emissions inventory, including the form of the particulate matter and the particle size
describe methods used to estimate emissions
explain overlap issues associated with point and nonpoint source emission inventories

## How Do I Define a Point Source of PM Fine or NH3 Emissions?

- Point sources are stationary sources included in a point source inventory
- Total plant (facility) emissions for a given pollutant is usually the criterion for deciding what sources to include in a point source inventory
- Criteria for including a stationary source in a point source inventory are determined by:
- State, Local, or Tribal regulations or policy, and/or
- Consolidated Emissions Reporting Rule (CERR)

**Notes:**
Point sources are stationary sources that are included in a point source inventory.  

Total plant or facility emissions for a given pollutant is usually the criterion for deciding if a specific source should be included in a point source inventory or an nonpoint source inventory.  

The criteria are defined by either state, local, or tribal regulations or policy.  They may also be defined by the reporting thresholds contained in the Consolidated Emissions Reporting Rule. 

## Filterable vs. Condensable

- Filterable PM are directly emitted
- Solid or liquid
- Captured on filter
- PM10 or PM2.5
- Condensable PM is in vapor phase at stack conditions
- Reacts upon cooling and dilution
- Forms solid or liquid particle
- Always PM2.5 or less

**Notes:**
Filterable PM:
solid or liquid particles directly emitted at stack or release conditions
captured on the filter of a stack test train
may be PM10 or PM2.5

Condensable PM: 
material that is in the vapor phase at stack conditions
condenses and/or reacts upon cooling and dilution in the ambient air 
forms a solid or a liquid particulate immediately after discharge from the stack
usually PM2.5 or less

## Sources of Filterable versus Condensible Emissions

- Combustion sources typically emit both filterable and condensible PM emissions
- Boilers
- Furnaces/kilns
- Internal combustion engines (reciprocating & turbines)
- Fugitive dust sources emit filterable emissions only
- Storage piles
- Unpaved roads at industrial sites

**Notes:**
Combustion sources typically emit both filterable and condensable emissions.  

Examples include boilers, furnaces and kilns, and both reciprocating internal combustion engines and turbines.  

Fugitive dust sources emit filterable emissions only.  

Examples of fugitive dust sources include storage piles and unpaved roads at industrial sites. 

## Primary vs. Secondary PM

- Primary PM is directly emitted and the sum of filterable and condensable
- Secondary PM is formed through chemical reactions and formed downwind of the source
- Precursors include SO2, NOx, and VOC
- Should not be reported in the inventory

**Notes:**
Primary PM:
the sum of the filterable and the condensable PM 
particles are emitted directly from a stack

Secondary PM:
particles that form through chemical reactions in the ambient air after dilution and condensation has occurred
formed downwind of the source
precursors include SO2, NOx, ammonia and VOC
should not be reported in the emission inventory (only precursor emissions are reported) 

## Sources of NH3 Emissions

- Industrial NH3 emissions can be placed into 3 broad categories related to the nature of the emissions source:
- Emissions from industrial processes
- Use of NH3 as a reagent in NOx control
- Refrigeration losses

**Notes:**
Sources of ammonia emissions fall into three broad categories: 
  industrial processes,
  use of ammonia as a reagent in NOx control (e.g., selective catalytic reduction or selective non-catalytic reduction), and 
  refrigeration losses.  

## Sources of NH3 Emissions (cont.)

- Examples of industrial processes that emit NH3 include:
- Combustion sources
- Ammonium nitrate & ammonium phosphate production
- Petroleum refining
- Pulp and paper production
- Beet Sugar Production
- These industrial processes represent the more significant emitters of NH3 in 2000 Toxics Release Inventory (TRI)

**Notes:**
The industrial processes shown here contribute significant amounts of ammonia emissions, as reported in the 2000 Toxics Release Inventory. 

## Resources for Identifying Point Sources of PM Fine and NH3

- EIIP Point Source Guidance (Volume II)
- List documents applicable to PM fine categories
- AP-42
- Existing Inventories
- National Emissions Inventory
- Toxics Release Inventory (TRI) for NH3

**Notes:**
Resources for identifying point sources of fine PM and ammonia include:
Volume II of the Emissions Inventory Improvement Program guidance document for point sources, 
AP-42 emission factors document, and 
existing inventories such as the NEI and the TRI (for ammonia). 

## What to Report to EPA

- PM2.5-PRI (or PM2.5- FIL & PM-CON individually)
- Note that all PM-CON is assumed to be PM2.5 size fraction
- PM10-PRI (or PM10-FIL & PM-CON individually)

**Notes:**
States may report their PM2.5 primary emissions to the EPA as either PM2.5 primary or the PM2.5 filterable and PM condensable components.

All PM condensable is assumed to be in the PM2.5 size.  

States may report their PM10 primary emissions to the EPA as either PM10 primary, or as PM10 filterable and PM condensable components.

## Implications

- Use the NIF 3.0 PM pollutant code extensions that identify the forms of PM (i.e., –PRI, –FIL, or –CON)
- Verify the form of the PM:
- Emission factors you use to calculate emissions; and
- PM emissions facilities report to you.
- Update your database management system to record these pollutant codes in NIF 3.0

**Notes:**
The NIF 3.0 PM pollutant code extensions:
identify forms of the PM, should be used for reporting.  
include PRI for primary filterable, FIL for filterable, and CON for condensable

The form of the PM should be verified to ensure that PM emissions that are recorded as PM10 or PM2.5 are correctly identified as filterable, condensable, or primary emissions.  This may require an examination of the emission factors.

If the emissions were reported by facilities, the verification will require that States contact the facilities to ask them what emission factors were used to calculate the emissions.  

Alternatively, if the emissions estimates provided by the sources are based on stack test data, the states must ask what method was used to measure the emissions in order to determine the form of PM. 

The database management system should be updated to record these pollutant code extensions. 

## How Do I Identify the PM Form?

- Test Methods upon which emission factors or emissions are based determine the form of PM:
- PM-FIL:
- EPA Reference Method 5 series, Method 17, Method 201/201A
- PM10-FIL/PM2.5-FIL:
- Particles-size analysis of PM-FIL (e.g., AP-42 EFs)
- Preliminary Method 4 being developed by EPA to measure both
- PM-CON:
- EPA Reference Method 202

**Notes:**
Examining the test method used to collect the data can identify the form of the PM.  

EPA’s Reference Method 5 series:
used to measure total PM filterable emissions
basis for most AP-42 emission factors (represent PM-filterable)

Method 17 is similar to the Method 5, however it is infrequently used.  Method 201/201A is designed for PM10 filterable.   

To calculate or measure the PM10 filterable or the PM2.5 filterable:
conduct a particle size analysis of the total PM to develop the size fractions or cut points for PM10 or PM2.5.   
use this information to develop particle size specific emission factors in AP-42

However, most of the emission factors in AP-42 are for filterable emissions, although there are some condensable emission factors for combustion sources.  Sum the filterable and condensable emission factors to obtain a PM primary emission factor.

There are some exemptions so it is important to always understand the form of the PM that the emission factor represents. 

The EPA is developing Preliminary Method 4 to measure both PM2.5 filterable and condensable. 

Method 202 is a method for condensable PM, but it is not used frequently, mainly because regulations do not require sources to measure condensable emissions. 

## AP-42 Particle Size Data

- Provides particle size distribution data and particle-size-specific emission factors
- Use AP-42 if source-specific data are not available
- Use data in chapters for specific source categories first
- Use Appendix B-1 data next
- Use Appendix B-2 data last

**Notes:**
AP-42 provides particle size distribution data and particle size specific emission factors.  

Some source categories (e.g., combustion) in AP-42 have particle size specific emission factors for PM. That data should be used first. 

Examine source specific data at the local or state level prior to consulting AP-42, since this is usually the best data.  

If such data does not exist, consult the resources listed.  

## AP-42 Particle Size Data (cont.)

- AP-42 chapters not always clear on what source test methods were used to develop particle size data
- See background documents for AP-42 chapters for details
- AP-42 available on EPA/OQAPS CHIEF web site
- http://www.epa.gov/ttn/chief/

**Notes:**
AP-42 chapters are not always clear on what source test methods were used to develop the particle size data.

You may need to consult the background information documents that were used to develop the chapters for AP-42.

AP-42 is available in EPA’s Clearinghouse for Inventories and Emission Factors website. 

## AP-42 Particle Size Data (cont.)

- Appendix B-1 (Particle Size Distribution Data and Sized Emission Factors for Selected Sources)
- Based on documented emission data available for specific processes
- Appendix B-2 (Generalized Particle Size Distributions)
- Based on data for similar processes generating emissions from similar materials
- Generic distributions are approximations
- Use only in absence of source-specific distributions

**Notes:**
Appendix B1:
use for source categories that do not have particle size specific emission factors  
contains particle size distribution data and particle size emission factors for selected sources
based on documented emissions data available for specific processes

If Appendix B1 does not have particle size data for the source category of interest, use Appendix B2.  

Appendix B2 contains generalized particle size distributions that are based on data for similar processes.  

These distributions are approximations and should only be used in the absence of source specific particle size distribution data. 

## Factor Information Retrieval (FIRE) Data System

- Latest version available was last updated October 2000 (Version 6.23)
- Currently being updated to:
- Incorporate revisions to 10 AP-42 chapters
- Add more PM10-FIL, PM25-FIL, and PM-CON emission factors

**Notes:**
The Factor Information Retrieval System (FIRE) is a compilation of emission factors from AP-42 and other documents.  

It is an electronic database that is available on the CHIEF web site.   

EPA is in the process of developing a more complete set of PM10 and PM2.5 filterable and PM condensable emission factors that will be incorporated into FIRE. 

## PM Calculator

- EPA tool for calculating uncontrolled/controlled filterable PM2.5 and PM10 emissions using AP-42 particle size distributions
- For point sources only
- Contains 2,359 SCCs with PM10 emissions in 1996 NEI

**Notes:**
The PM Calculator is a tool developed by EPA to calculate uncontrolled and controlled filterable PM2.5 and PM10 emissions using AP-42 particle size data.  

For example, it can be used to calculate the PM2.5 filterable emissions based on the PM10 filterable emissions contained in an inventory.  

You can also calculate PM10 and PM2.5 from the total PM filterable emissions.  

The calculator only deals with the filterable emissions (i.e., it does not address the condensable portion) and is for point sources only. It contains over 2300 SCCs.

## PM Calculator (cont.)

- Limitations
- AP-42 particle size data not available for many sources; generic AP-42 profiles are used for many source categories
- Available on EPA/OQAPS CHIEF web site
- http://www.epa.gov/ttn/chief/software/index.html

**Notes:**
Although it contains over 2300 SCCs, the PM calculators main limitation is that it is based on AP-42 particle size data that is not available for many sources.  

As a result, many times it uses the generic particle size data contained in Appendix B2 of AP-42 or other sources.  It is also available on the CHIEF web site. 

## Point & Area Source Emissions Inventory (EI) Overlap Issues

- For categories included in Point and Area EIs:
- Subtract total point activity from total state activity to obtain total area activity
- Total Area Activity = Total Activity – Σ Total Point Activity
- Example for Fuel Combustion Sources:
- Point activity: fuel throughput from point source EI survey
- Total activity: fuel throughput from State/local gov. agencies or U.S. DOE/EIA State Energy Data reports

**Notes:**
For categories included in the point and nonpoint source emission inventories, subtract total point activity from the total state activity to obtain a total nonpoint source activity.  

Using the fuel combustion category as an example, the point source activity is the fuel throughput from the point source inventory. 

Total activity is the statewide fuel throughput obtained from the state or local government agency, or from the state energy data reports published by the Interior Energy Administration in the U.S. Department of Energy. 

## Point & Area Source EI Overlap Issues (cont.)

- Basis of Point Source Subtraction
- Activity-based calculation is preferred
- Emissions-based calculation is acceptable when activity is not available:
- Total source category activity and point activity need to be on same control level (usually uncontrolled)
- Back-calculation of uncontrolled emissions for controlled processes may overstate uncontrolled emissions

**Notes:**
Ideally, the point source subtraction is based on activity data.  For example, the point source fuel throughput for a given year is subtracted from the total statewide fuel consumption for the same year.  

However, in many cases, the activity data for performing that calculation may not be available.  In this case, an emissions based calculation is acceptable.   

Under the emissions based approach:
the total source category activity and the point activity should be on the same control level  
the control level should be an uncontrolled emissions basis because since total statewide activity represents uncontrolled sources

In this case, it is important to ensure that the point source emissions represent uncontrolled levels.   It is also important to check the uncontrolled emissions to ensure  that they seem reasonable.

## Point & Area Source EI Overlap Issues (cont.)

- Geographic level of calculation may affect results:
- Issue when using surrogate activity data (e.g., employment, housing, population) to allocate total State activity to counties
- Subtracting county totals may produce negative results due to inaccuracy of allocation method
- Subtracting State totals less likely to produce negative results at county level
- Point source adjustments to surrogate allocation data (e.g., employment) should be done if available from point EI survey

**Notes:**
The geographic level of the point source adjustment used to calculate the nonpoint source activity is an issue when surrogate activity data is used to allocate total state activity to the county level.  

The EIIP method:
uses employment for specific SIC codes to allocate total statewide natural gas combustion to the county level at industrial and commercial institutions
requires you to sum point source throughput for a county and subtracting it from the total activity for the county may produce negative results 
indicates that point source consumption fuel use is higher than that calculated for the nonpoint sources
can be an artifact of the allocation data used   

The preferred approach: 
sum up the point source fuel throughput consumption on the state level
subtract this sum from the total consumption for the state prior to doing the county-level allocation

It is also preferable to obtain activity data such as employment data for the point sources included in the inventory.  

In this way it is possible to make point source adjustments to the surrogate allocations to account for the amount of employment that is associated with the point sources. 

## Point & Area Source EI Overlap Issues (cont.)

- QA/QC Results
- Review county-level area source estimates for reasonableness
- Make adjustments based on experience of your agency’s personnel:
- If allocation method places area source activity in a county for which you know there is no activity, exclude the county from your allocation
- If all of a county’s activity is covered by the point EI, set the activity for the county to zero

**Notes:**
The county level nonpoint source estimates should be reviewed for reasonableness after the adjustment has been made.  

Adjustments should be based on the experience of the agency personnel.  

For example, if the allocation method places nonpoint source activity in a county for which it is known that there is no activity, that county should be excluded from the allocation.   

Also, if all of a county’s activity is covered by the point source emission inventory, the nonpoint source emissions should be zero. 

## Point & Area Source EI Overlap Issues (cont.)

- Reporting of small point sources in area CERR submittal:
- If your point EI includes sources with emissions below the CERR point EI reporting thresholds, you may include the emissions for these small sources in the area EI
- To avoid double counting in the area EI, subtract total point source activity or emissions from total State-level activity or emissions before rolling up emissions for small point sources to be included in your area EI

**Notes:**
If the point emission inventory includes sources with emissions below the CERR point emission inventory reporting thresholds, the emissions for these small sources can be included in the nonpoint source emissions.  

To avoid double counting in the nonpoint source inventory:  
subtract total point source activity from the total state activity, then 
roll up the small point source data to add to the inventory.  

In this way the emissions for the small point sources in the area are not double counted. 

## Reading List

*Stationary Source Control Techniques Document for Fine Particulate Matter*, EPA/OAQPS, Oct. 1998
- (http://www.epa.gov/ttn/oarpg/t1/meta/m32050.html)
*Emission Inventory Guidance for Implementation of Ozone and Particulate Matter National Ambient Air Quality Standards (NAAQS) AND Regional Haze Regulations, EPA/OAQPS*
- (http://www.epa.gov/ttn/chief/eidocs/publications.html)
*Introduction to Stationary Point Source Emission Inventory Development*, EIIP Vol. 2, Chapter I, May 2001
*How to Incorporate Effects of Air Pollution Control Device Efficiencies and Malfunctions into Emission Inventory Estimates*, EIIP Vol. 2, Chapter 12, July 2000

**Notes:**
A suggested reading list for preparing point source inventories for fine PM is presented here.