### CHAPTER 3

DEVELOPMENT OF THE TOXICS EMISSIONS INVENTORYMATES III Final Report

3-1 

## Chapter 3. Development of the Toxics Emissions Inve ntory

3.1 Introduction An emissions inventory of air pollutants and their sources is essential in order to identify the major contributors of air contaminants and the meas ures required to reduce air pollution. Information necessary to produce an emissions inven tory for the Basin is obtained from the SCAQMD and other government agencies including: Ca lifornia Air Resources Board (ARB); California Department of Transportation (Caltrans); and Southern California Association of Governments (SCAG).

Each of these agencies is responsible for collectin g data (e.g., industry growth factors, socioeconomic projections, travel activity levels, emiss ion factors, emission speciation profiles, etc.) and developing methodologies (e.g., model and demog raphic forecast improvements) required to generate a comprehensive emissions inventory. SCAQ MD is solely responsible for developing the point source inventory, and the area source inv entory is developed jointly by SCAQMD and ARB. ARB is the primary agency responsible for dev eloping the emissions inventory for all mobile sources. SCAG is the primary agency for pro jecting population and activity growth in the Basin. ARB provides on-road and off-road inven tories from their EMFAC and OFF-ROAD Models, respectively. Caltrans provides SCAG with highway network, traffic counts, and road capacity data. SCAG incorporates these data into t heir Travel Demand Model for estimating/projecting vehicle miles traveled (VMT) and speed. ARB’s on-road inventory also relies on SCAG’s VMT estimates.

3.2 Overview
The toxic emissions inventory for MATES III consist s of four components: (1) point sources; (2) area sources; (3) on-road mobile sources; and (4) o ff-road (or other) mobile sources. Point source emissions are from facilities having one or more pieces of equipment registered and permitted with the SCAQMD and with emissions above certain threshold levels. Area sources represent numerous small sources of emissions that can collectively have significant emissions (e.g., dry cleaners, retail gasoline stations, auto body shops, residential heating, etc.). On-road mobile sources include cars, trucks, buses, and mot orcycles. All mobile sources not included in the on-road mobile source inventory are considered as “off-road” mobile sources, which include aircraft, ships, commercial boats, trains, recreati onal vehicles, construction equipment, etc.

The 2007 Air Quality Management Plan (AQMP) [1] is the basis for the toxics emissions inventory developed for MATES III. The 2005 invent ory used for the MATES III modeling analysis is projected from the 2002 baseline emissi ons inventory in the 2007 AQMP. All the future year inventories in the 2007 AQMP are also p rojected from the 2002 baseline emissions inventory. A “top-down” approach is used to develo p the toxics inventory, that is, toxicMATES III Final Report

3-2 emissions are calculated by applying the latest ARB speciation profiles [2] to the hydrocarbon and particulate matter emissions. Speciation profiles provide estimates of the emission’s chemical composition. The ARB maintains and updates the che mical composition and size fractions of particulate matter (PM) and the chemical compositio n and reactive fractions of total organic gases (TOG) for a variety of emission source catego ries. The source type (e.g., equipment and fuel) is used to identify the appropriate speciatio n profile.

A top-down approach is preferable for a regional mo deling risk analysis, such as MATES III, for the following reasons:

• Speciating the VOC and PM inventory affords consist ency with the 2007 AQMP.

• The photochemistry algorithms in the MATES III mode ling system require the complete speciation of the VOC emissions to ensure their cor rect application. An inventory of just reported toxic species would be insufficient.

• Lastly, the computer programs used to grow and cont rol the VOC and PM emissions into the future for the 2007 AQMP can also be used for p rojecting the toxic emissions in MATES III. Thus, future air toxics risk reductions resulting from the 2007 AQMP can be estimated.

3.3 Point Sources The 2002 point source emissions inventory is based on the emissions data reported by the point source facilities in the 2002/2003 Annual Emissions Reporting (AER) Program and is the basis for the 2005 inventory used for MATES III modeling analysis. This program applies to facilities emitting four tons or more of VOC, NOx, SOx, or PM or emitting more than 100 tons of CO per year. Facilities subject to the AER Program calcul ate and report their emissions primarily based on their throughput data (e.g., fuel usage, materia l usage), appropriate emission factors or source tests, and control efficiency (if applicable). Und er the 2002/2003 AER Program, approximately 3,200 facilities reported their annual emissions to the SCAQMD. Emissions from smaller industrial facilities not subject to the AER Progra m, which represent a small fraction of the overall stationary source inventory, are included a s part of the area source inventory (see Section 3.3).

In order to prepare the point source inventory, emi ssions data for each facility are categorized based on U.S. EPA’s Source Classification Codes (SC Cs) for each emission source category. Since the AER collects emissions data on an aggrega te basis (i.e., equipment and processes with the same emissions factor are grouped and reported together), facility’s equipment permit data are used in conjunction with the reported data to a ssign the appropriate SCCs and develop the inventory at the SCC level. For modeling purposes, facility location is specified in Universal Transverse Mercator (UTM) coordinates. The busines s operation activity profile is also recorded so that the annual emissions can be distributed tem porally throughout the day, week, and year.MATES III Final Report

3-3 Toxic emissions are calculated by applying the late st ARB speciation profiles [2] to the hydrocarbon and particulate matter emissions. The SCC is used to identify the appropriate speciation profile for the source.

3.4 Area Sources The area source emissions developed for the 2007 AQ MP and projected to the year of interest (i.e., 2005) are used for MATES III. SCAQMD and AR B shared the responsibility for developing the 2002 area source emissions inventory for approximately 350 area source categories. Specifically, SCAQMD developed the are a source inventory for about 93 categories and ARB developed the remaining area source categor ies (of which 239 categories are associated with consumer products, architectural coatings, and degreasing). For each area source category, a specific methodology is used for estimating emiss ions. Emissions are spatially allocated to 2 km by 2 km grids using spatial surrogates. Some co mmonly used spatial surrogates are listed in Table 3-1. As with the point source inventory, tox ic emissions are calculated by applying the latest ARB speciation profiles to the hydrocarbon a nd particulate matter emissions.

3.5 On-Road Mobile Sources On-road emissions are the product of emission facto rs and vehicular activity. The emissions developed for the 2007 AQMP and projected to calend ar year 2005 are used for MATES III. For the 2007 AQMP, ARB’s EMFAC2007 (v2.3) emission fact ors [3] were used and link-based traffic volumes and speeds were obtained from the SCAG regi onal transportation modeling. The Direct Travel Impact Model (DTIM) was used to link emissio n factors and transportation modeling results and generate hourly gridded emissions of cr iteria pollutants (i.e., TOG, NOx, PM, CO, and SOx). Toxic emissions are calculated by applyi ng the latest ARB speciation profiles for mobile sources to the hydrocarbon and particulate m atter emissions. A flow chart illustrating this process is provided in Figure 3-1. Some of th e key steps in the process are discussed in more detail below.

EMFAC stands for EMission FACtor. It is a FORTRAN computer model that estimates the onroad emissions of hydrocarbons (HC), CO, NOx, PM, l ead (Pb), SO 2 , and CO 2 for calendar years 1970 to 2040. EMFAC considers 1965 and newer vehic les powered by gasoline, diesel, or electricity and reports for 13 broad vehicle classe s as shown in Table 3-2. Over 100 different technology groups are accounted for within each cla ss (e.g., catalyst, non-catalyst, three-way catalyst, carbureted, multi-port fuel injection, LE V, TLEV, SULEV, etc.).

EMFAC currently considers the following county-spec ific information when calculating emissions:

• Ambient air temperature (denoted by T in Figure 3-1 );

• Relative humidity (denoted by RH in Figure 3-1);

• Vehicle population;MATES III Final Report

3-4 • Fleet composition;

• Fleet growth rates;

• Mileage accrual rates;

• Vehicle age distribution;

• Distribution of VMT by speed;

• Smog check regulations;

• Fuel properties; and

• Altitude.

Some on-road activity information for the four coun ties in the Basin is summarized in Table 3-3. Four of the top seven counties in California in ter ms of vehicle population, VMT, and trips are in the Basin.

The output from EMFAC is a text file containing HC, CO, NOx, PM, lead, SO 2 , and CO 2 emission rates for 45 model years for each vehicle class within each calendar year, for 24 hourly periods, and for each month of the year for each co unty/air basin specified. Processing continues with the DTIM modeling system, which prepares gridd ed hourly on-road emissions for photochemical grid modeling.

The DTIM processing system consists of three FORTRA N Program modules: CONVIRS4, IRS4, and DTIM4. The main function of CONVIRS4 is to re-format the emission rate file output from EMFAC into a form compatible with IRS4. IRS4 creates fleet average emission rates by ambient air temperature, relative humidity , and vehicle speed.

The DTIM4 module prepares gridded, hourly on-road e missions of HC, CO, NO X , PM, lead, SO 2 , and CO 2 link by link in the transportation network. SCAG’ s Travel Demand Model provides the following for each link in the transpo rtation network: the number of vehicles, their average speed, and time on the link. Separate file s containing hourly gridded temperature (T in Figure 3-1) and relative humidity (RH in Figure 3-1 ) are provided as input to DTIM4. Knowing the air temperature and relative humidity represent ative of the link and the average vehicle speed on the link, DTIM4 looks up the fleet average emiss ion rate in the file prepared by IRS4, and multiplies these by the number of vehicles and the average time on the link.

ARB speciation profiles are used to speciate the on -road HC and PM emissions into its toxic components.MATES III Final Report

3-5 3.6 Off-Road Mobile Sources The off-road emissions developed for the 2007 AQMP are used for MATES III. For the 2007 AQMP, ARB’s OFF-ROAD model [4] was used to estimate emissions for all off-road ca tegories (100+ source categories) except commercial ships, a ircraft, locomotive, and recreational vehicles. This model incorporates various aspects of off-road elements, such as the effects of various adopted regulations, technology types, and seasonal conditions on emissions. The model combines population, activity, horsepower, load fac tors, and emission factors to yield the annual equipment emissions by county, air basin, or state. Spatial and temporal features are incorporated to estimate seasonal emissions. Emiss ions are spatially allocated to 2 km by 2 km grids using spatial surrogates. Toxic emissions ar e calculated by applying the latest ARB speciation profiles for off-road mobile sources to the hydrocarbon and particulate matter emissions.

The diesel particulate emissions from the major sou rce category of “Ships and Commercial Boats” differ between the 2007 AQMP and MATES III. “Ships and Commercial Boats” consists of 16 Category of Emission Source (CES) codes. For the 2007 AQMP, 13 out of 16 CESs were assumed to fall into the category of diesel interna l combustion. It has since been determined and assumed for MATES III that all 16 CESs involve dies el internal combustion. The fuels identified in the three ship emissions categories ( 82172 -military and coast guard ships, 82214- crew and supply boats, offshore oil production, and 47654 -tugboats) were previously categorized as unspecified liquids and consequently are not included as diesel. Further inventory reconciliation determined that the ships in these c ategories were actually burning diesel fuels. This resulted in an additional 0.42 ton/day of dies el particulate attributed to “Ships and Commercial Boats” in the MATES III 2005 inventory.

3.7 Summary of Toxic Emissions Table 3-4 presents the emissions from selected comp ounds apportioned by the on-road, off-road, point, and area source categories. Chemicals that are considered potential or known human carcinogens are denoted with a check mark. Toxic e missions by major source categories are provided in Appendix VIII.

Species and source apportionment are shown in Table 3-5 and Figure 3-2, respectively. In those illustrations, the emissions of the carcinogenic po llutants in Table 3-4 are weighted by the ratio of their cancer potency to the cancer potency of di esel particulate matter (DPM). (Cancer potencies developed by the State of California Offi ce of Environmental Health Hazard Assessment were used). Thus, emissions from specie s less potent than DPM (e.g, benzene, perchloroethylene, etc.) are weighted less, while e missions from species more potent than DPM (e.g., hexavalent chromium, arsenic, etc.) are weig hed more. DPM has a weighting factor of

one.

As shown in Table 3-5, DPM accounts for over 85% of the overall potency weighted emissions. The other significant compounds (i.e., contribution s >1%) are 1,3-butadiene, benzene,MATES III Final Report

3-6 perchloroethylene, and hexavalent chromium. On-roa d and off-road mobile sources contribute nearly 93% of the potency weighted air toxics emiss ions and stationary (i.e., point and area) sources contribute about 7% of the potency weighted risk (Figure 3-2).

Carcinogenic potency weighted emissions have decrea sed by 11% since MATES II (1998 inventory year) as shown in Figure 3-3. Emissions from on-road, point, and area source categories decreased by 12%, 66%, and 42%, respecti vely and off-road emissions are essentially unchanged (an increase of 1%). To perform the comp arison, the 2002 inventory used in the 2007 AQMP was back-cast to 1998 in order to account for changes to the EMFAC and OFF-ROAD models that have occurred since MATES II. These em issions for air toxics are tabulated in Appendix VIII.

3.8 Selected Emissions and Air Quality Changes Sin ce MATES II Table 3-6 compares emission and air quality changes since MATES II for selected toxics. The air quality change is compared to the MATES III yea r 1 average from the ten fixed monitoring sites. Emissions have decreased and air quality ha s improved since the MATES II (i.e., 1998 timeframe). It should be noted that the difference for some pollutants, such as cadmium and arsenic, may also be due to lower method reporting limits in MATES III, as discussed in Chapter 2.

Several caveats are appropriate when comparing the changes in inventory emissions and ambient measurements. For example, weather and dispersion of emissions are not considered, which can influence the relationship between emissions and am bient concentrations. Also, the inventory is a regional estimate of total emissions throughout t he Basin, whereas ambient measurements are from the ten fixed monitoring locations where there may be influences from local sources. Another difference is that secondary formation or d egradation of substances is not accounted for. Nonetheless, comparing emissions estimates with air quality measurements can provide information on whether expected emissions changes a re reflected in ambient measurements, can be used to help calibrate emissions, and may sugges t where emissions inventory methods can be improved.

3.9 References

1. A copy of the 2007 AQMP can be viewed or downloaded at the following SCAQMD link: http://www.SCAQMD.gov/aqmp/07aqmp/index.html

. 2. ARB speciation profiles can be viewed or downloaded from the following ARB link: http://www.arb.ca.gov/ei/speciate/speciate.htm

. 3. EMFAC2007 model and its documentation can be obtain ed at the following ARB link: http://www.arb.ca.gov/msei/onroad/latest_version.ht m

. 4. The OFF-ROAD Model and its documentation can be obt ained at the following ARB link: http://www.arb.ca.gov/msei/offroad/offroad.htm

.MATES III Final Report

3-7 Table 3-1. Commonly Used Spatial Surrogates

. Population Total employment

VMT Industrial employment
Length of rail per grid cell Retail employment
Locations of unpaved rural roads Single dwelling un its
Total housing Rural land cover – range land
Agricultural land cover Rural land cover – forest

National forest > 5000 ft

Source: http://eos.arb.ca.gov/eos/projects/surrogates/

Table 3-2. Broad Vehicle Classes Considered by EMFAC

. Vehicle Class Weight (lbs) Vehicle Class Weight (lb s)
Passenger cars All Heavy-Heavy-Duty Truck 33,001 – 60,000 Light Truck I 0 – 3,750 Motorcycle All Light Truck II 3,751 – 5,750 Urban Diesel Bus All Medium-Duty Truck 5,751 – 8,500 School Bus All Light-Heavy-Duty Truck I 8,501 – 10,000 Other bus A ll Light-Heavy-Duty Truck II 10,001 – 14,000 Motor Hom es All Medium-Heavy-Duty Truck 14,001 – 33,000 Source: Adopted from the User’s Guide for EMFAC200 7.

Table 3-3. Vehicle Activity Information for the Counties in th e Basin.

County Vehicle

Population VMT/day Trips/day Miles per Vehicle-Day Mean Age of

Passenger Car Fleet (years)
Los Angeles 5,811,255 197,059,000 39,896,020 33.91 9.36 Orange 2,071,490 65,359,000 14,058,600 31.55 10.46 Riverside 1,014,703 42,170,000 6,890,676 41.56 11.9 1 San Bernardino 1,064,007 39,152,000 7,298,540 36.80 9.99

Source: http://www.arb.ca.gov/msei/onroad/briefs/activity.p dfMATES III Final Report

3-8 Table 3-4. 2005 Annual Average Day Toxic Emissions for the Sou th Coast Air Basin.

Emissions (lbs/day) Pollutant
On-road Off-road Point Area Total  Acetaldehyde* 4857.0 8622.4 125.8 505.1 14110.3
Acetone** 4020.5 7189.1 552.4 28904.9 40666.9  Benzene 13244.8 7808.3 906.5 609.3 22568.9  1,3 Butadiene 2723.1 1755.6 537.1 108.7 5124.5  Carbon tetrachloride 0.0 0.0 11.2 0.0 11.2  Chloroform 0.0 0.0 206.9 0.0 206.9  1,1 Dichloroethane 0.0 0.0 0.5 0.0 0.5  1,4 Dioxane 0.0 0.0 0.8 0.7 1.5  Ethylene dibromide 0.0 0.0 2.2 0.0 2.2  Ethylene dichloride 0.0 0.0 67.2 0.0 67.2  Ethylene oxide 0.0 0.0 16.1 52.6 68.7  Formaldehyde* 12596.6 19889.0 1488.8 1302.0 35276. 4 Methyl ethyl ketone* 745.6 1366.0 1244.3 6466.7 98 22.6  Methylene chloride 0.0 0.0 325.1 13548.3 13873.4  MTBE 0.0 4.4 89.6 0.0 93.9  Naphthalene 573.4 376.8 16.6 568.1 1534.9  p-Dichlorobenzene 0.0 0.0 115.4 5553.9 5669.3  Perchloroethylene 0.0 0.0 940.4 9685.3 10625.7  Propylene oxide 0.0 0.0 2.2 0.1 2.3 Styrene 681.7 326.3 1332.5 76.5 2417.0
Toluene 37707.9 15369.2 8724.3 21029.4 82830.8  Trichloroethylene 0.0 0.0 587.1 633.0 1220.1  Vinyl chloride 0.0 0.0 51.1 0.0 51.1

 Arsenic 0.2 3.9 13.4 24.8 42.3  Cadmium 1.5 2.1 3.2 7.2 14.0
Chromium 21.1 9.2 49.2 77.3 156.8  Diesel particulate 22164.5 37406.2 489.5 618.3 606 78.5
Elemental carbon*** 10498.2 9337.4 4850.4 14197.3 38883.3  Hexavalent chromium 1.1 0.6 0.6 0.5 2.8  Lead 2.4 4.8 13.7 180.9 201.8  Nickel 15.3 5.8 44.2 23.4 88.7 Organic carbon 19972.7 18073.3 371.0 69230.1 10764 7.1
Selenium 0.5 0.5 41.4 2.2 44.6
Silicon** 838.7 136.5 1211.9 218527.2 220714.3

 Denotes potential or known human carcinogen. * Primarily emitted emissions. These materials are also formed in the atmosphere as a result of photo chemical reactions. ** Acetone and silicon are not toxic compounds. Th eir emissions are included here because they were m easured in the sampling program and were subsequently modeled for the purpose of model evaluation. *** Includes elemental carbon from all sources (inc luding diesel particulate).MATES III Final Report

3-9 Table 3-5. Cancer Potency Weighted Species Apportionment for 2 005 Emissions.

Toxic Contribution (%) Toxic Contribution (%)
Diesel particulate 85.64 Ethylene oxide 0.03 1,3-butadiene 3.94 Vinyl chloride 0.02 Benzene 2.90 Trichloroethylene 0.01 Perchloroethylene 2.86 Lead 0.01 Hexavalent chromium 1.83 Ethylene dichloride < 0.01 Formaldehyde 0.95 Chloroform < 0.01
Arsenic 0.65 Carbon tetrachloride < 0.01 p-dichlorobenzene 0.29 Ethylene dibromide < 0.001
Cadmium 0.27 MTBE < 0.001 Naphthalene 0.24 1,4-dioxane < 0.0001 Acetaldehyde 0.18 Propylene oxide < 0.0001 Nickel 0.10 1,1-dichloroethane < 0.00001 Methylene chloride 0.06

Table 3-6. Selected Emissions and Air Quality Changes Since MA TES II.

Toxic Gases Change in

Emissions Change in

Air Quality Toxic Particulates Change in Emissions Change in

Air Quality
Acetaldehyde -9% -8% Arsenic** -20% -54%
Benzene -36% -47% Cadmium** -20% -74% 1,3-butadiene -31% -67% Elemental carbon* -3% -28%* Formaldehyde -21% -9% Hexavalent chromium -53% -5% Methylene chloride -38% -43% Lead -14% -47% Perchloroethylene -58% -77% Nickel -22% -31% Trichloroethylene -65% -79%

Notes: * Adjusted for instrumentation changes in MATES III ; see Section 2.6.3. ** Difference in air quality may be in part due to lower laboratory reporting limits in MATES III. Emissions: 2005 compared to 1998. Air Quality: MATES III year 1 compared to MATES II annual averages from 10 fixed sites.MATES III Final Report

3-10 EMFAC2007

DTIM4

Gridded hourly emissions of HC, CO, NO x , PM, Pb, SO 2 , & CO 2

ARB TOG & PM Specification Profiles

Gridded hourly toxic emissions IRS4 CONVIRS4

Meteorological Model

Gridded fields of T & RH SCAG Travel Demand Model

Link data: • Vehicle count • Speed • Time on link

Figure 3-1. Flow Diagram for On-Road Emissions Processing.

On-road 36.3%

Off-road 56.4% Point

2.3% Area 5.0%

Figure 3-2. Cancer Potency Weighted Source Apportionment for 20 05 Emissions.MATES III Final Report

3-11 Figure 3-3. Cancer Potency Weighted Emission Comparison of MATE S II and MATES III. 0 20,000 40,000 60,000 80,000

MATES-II (1998) MATES-III (2005)Emissions as DPM (lbs/day)

On-road Off-road Point Area 

### 42% decrease Area 66% decrease Point 1% increase Off-road 12% decrease On-road 

## Percent

Change Source Category