A-1

Appendix A: Methodology to Revise VOC from Residential 

Wood Combustion 

Purpose: Calculate corrected VOC emissions for EPA and State/local supplied sources with 

SCC=2104008001 which is Fireplaces (FP) and SCC=2104008000 (total RWC; i.e. it includes 

fireplaces AND woodstoves) because we have evidence that with the exception of Calif., an 

erroneously high emission factor (229 lb/ton) was used. 

Note that the 229 lb/ton was the EF in AP-42, but numerous studies have shown it to be too high 

by approximately an order of magnitude. We chose to use the emission factor from the MidAtlantic Regional Air Management Association (MARAMA) study of 18.9 lbs VOC/ton. 

The evidence for the State/local supplied data using the 229 lb/ton EF is the ratio of VOC to 

PM2.5 which is much greater than what is expected when computed at the state and/or county 

level. Using the the erroneous VOC emission factor of 229 lb/ton EPA factors, the VOC-toPM2.5 ratio should be 9.7 (VOC = 229 lb/ton and PM25 = 23.6 lb/ton). But this ratio can vary if States 

use different PM2.5 ratios. 

Because the RWC data is provided in different ways (one example is that states provide the data 

aggregated for fireplace and woodstove SCCs rather than use the separate SCCs) and we don’t know 

what particular emission factors States used, we had to develop different adjustments for different cases. 

The caes are described below.
A-2

CASE 1: Adjustment of VOC from 2104008001 for counties that have VOC emissions for 

BOTH fireplace SCCs (2104008001) and woodstove SCCs (any combination of 

21040080XX, where XX not equal to 01 or 00)

Except for California (which we don’t change), recompute VOC from 2104008001 as follows: 

VOCcorrected=VOCold*(EFcorrected/EFold) 

Where EFcorrected=18.9 lbs VOC/tons of wood burned. 

And EFold=229 lbs VOC/tons of wood burned. 

Leave VOC from woodstove SCCs as is. 

Apply FP VOC change to the following 35 States based on the value of their VOC to PM2.5 ratio for 

SCC=2104008001. 

State Comment regarding VOC to PM2.5 ratio 

 AZ CO DC

 FL GA 

 IA KS KY

 LA MN MO

 MT NC ND

 NE NM NV

 OK OR(#1)

 PA RI SD

 TN WI(#2) 

 WY 

States appear to use the 229 EF (based on their VOC-toPM2.5 ratio of 9.7). For these States, this correction is 

most accurate. Note that the top 2 VOC emitting states 

are in this list. 

IL IN MI WV have a VOC-to-PM2.5 ratio of 19.4, which may mean 

that they use a lower PM2.5 EF (11.8 lbs/ton?) or higher 

VOC EF (not likely). The calculation may be less 

accurate for these states, since we are unsure of the VOC 

EF that they used. 

TX – EPA provided data Ratio is 3.55. Wood stove EFs different (but not that far off) of 

EPA data for Colorado. 

TX – State submitted data Ratio is 10.73. Wood stove EFs different (but not that far off) 

of EPA data for Colorado. 

VT Ratio is 7.12. Other woodstove VOC to PM ratios are 

slightly higher than for the EPA data, but are not that far 

away. 

NY Ratio is 7.88. Same ratio for outdoor wood burning but 

woodstove ratio is on the order of the EPA 

WA – local data only 

 Counties 53-033, -035, -053, -061 

ratio is 12.32. Wood stove ratios slightly higher than for 

the EPA data, but are not that far away. 

MS Ratio is 33.68. ratios for 2104008002, 2104008003,

2104008004 are also pretty different (higher) than EPA, 

but VOC emissions from these are not nearly as large as 

21040080001. 
A-3

CASE 2. Adjustment of VOC from 2104008000 from MARAMA states

State Comment 

CT DE MA MD ME NH Ratio of VOC to PM2.5 is 4.7 

They did not break out fireplace emissions from woodstove emissions. Need to know what EFs 

they used for fireplaces. 

Madeleine contacted Marama on Friday June 27 (Julie R. McDill 

Mid-Atlantic Regional Air Management Association 

8900 LaSalle Road Suite 636 

Baltimore, MD 21286 

P. 443-901-1882 

F. 443-901-1886 

Email: jmcdill@marama.org 

www.marama.org) to find out what they used so we know if/how to correct VOC. 

She indicated that for the 2002v3 nonpoint, they had not used corrected VOC. 

THUS USE CASE3 DIRECTIONS FOR CASE2 

CASE 3. Adjustment of VOC from 2104008000 from non-MARAMA states and where 

2104008000 is the only SCC used.

Approach: Divide out the VOC from the broad into fireplaces, uncontrolled woodstoves & 

controlled woodstoves using PM2.5 and then compute VOC from VOC/PM2.5 EFs, correcting 

the VOC EF for fireplaces. 

Step 1. break out PM2.5 into fireplaces (FP), uncontrolled-woodstoves, controlledwoodstoves using the following factors: 0.194, 0.715, 0.091 (respectively) 

Step 2. multiply fireplaces PM2.5 by (18.9/23.6) to get corrected FP VOC (numerator is 

corrected VOC EF for fireplaces, denominator is EF used for PM2.5 for fireplaces, NEI 

documentation, Table 4) 

multiply uncontrolled-woodstoves PM2.5 by *(53/30.6) to get uncontrolled-woodstoves 

VOC (numerator is VOC EF for the uncontrolled-woodstove SCCs: 2104008002 and 

2104008010. Denominator is PM2.5 EF for the uncontrolled woodstoves. These values are 

from the NEI documentation, table 5) 

multiply controlled-woodstoves PM2.5 by *(12/19.6) to get controlled-woodstoves VOC 

(numerator/denominator are VOC&PM2.5 EFs for controlledwoodstove SCCs : 2104008003 

and 8050 from NEI documentation, table 6 – assume most emissions are from 2104008003 

and 8050 since other controlled-woodstoves SCC: 2104008004, has different ratios – 

(15/20.4) ) 

Step 3. Sum up VOC and use that as the corrected VOC for 2108004000 
A-4

Step 4. compute corrected ratio VOC to PM2.5 (NOTE THAT PM2.5 doesn’t change from the 

original value) just to check. Should be about 1.45 

Sample Calculation for AR is shown below. 

Apply to: 

State Comment 

AR Ratio is 2.49. AR pm2.5 from broad SCC is 2485 

tons. Example calc shows how to derive corrected 

VOC. Statewide VOC goes from 6177 tons to 3605 

tons. 

ID PM2.5 has different data source code than VOC. 

PM2.5 total from ID is 2263 tons. Data source code

for PM2.5 is S-02-X-PR. Shouldn’t be a problem to

do that calc. Statewide VOC goes from 15K to 3300.

AZ local data 

(Maricopa county only) 

Pm2.5 is 409, VOC was 2912. corrected VOC is 593 

NJ – EPA data ratio is 6.62 

based on bad VOC and AP-42 

PM2.5 for fireplaces 

PM= 4419. VOC was 29K corrected VOC is 6405 

NJ state data ratio is 1.73. PM = 4392. VOC was 7607. corrected VOC is 6366. 

Ohio VOC to PM2.5 ratio is 

1.67 

PM=8936. VOC was 14962 corrected VOC is 12952 

TN local data VOC to PM2.5 

ratio is 6.62 

UT state data. ratio is 3.05 

WA state data. Ratio is 3.9 

AR example calc: 2485 tons of PM2.5 and presumably bad VOC of 6177 tons 

.194*2485=482 PM2.5 from FP 

.715*2485=1779.6 from uncontrolled-woodstoves 2104008002, 2104008010, or 2104008051 

.091*2485=223.69 from controlled-wood stoves. 2104008003, 2104008004, 2104008030, 

2104008050, 2104008052 or 2104008053 

Apply VOC to PM2.5 factor for FP: 482*(18.9/23.6)=386 tons VOC 

Apply VOC to PM2.5 factor for uncontrolled-woodstoves (8002): 1779.6 *(53/30.6) = 3082 tons 

VOC 

Apply VOC to PM2.5 factor for controlled-wood stoves (8003): 223.69*(12/19.6)=136.95 tons 

Sum of VOC = 3605 tons -------this is the corrected VOC for 2104008000. 

So corrected ratio is 3605/2485=1.45 looks good. 
A-5

CASE 4. Virginia, which has no VOC for wood stoves, but there is PM. And has VOC (but 

no PM for broad SCC).

state_a

bbr 

Scc data_sour

ce 

PM2_5 VOC 

VA 2104008000 S-02-X 53825.14

VA 2104008001 E-01-G 831.2484

VA 2104008002 E-01-G 3632.713

VA 2104008003 E-01-G 144.1626

VA 2104008004 E-01-G 60.54522

VA 2104008010 E-01-G 4937.689

VA 2104008030 E-01-G 82.29481

VA 2104008050 E-01-G 195.95

VA: remove all records with 2104008000 and compute VOC for all other SCCs using VOC to PM2.5 

ratios. 

For 2104008001 (fireplaces) use: (18.9/23.6)

For uncontrolled woodstoves: 2104008002, 2104008010, or 2104008051 use (53/30.6) 

because both 2104008002, 2104008010 use that and there are no factors for 2104008051

For controlled wood stoves use the following based on SCC: 

2104008003 (12/19.6), 

2104008004 (15/20.4 using Table 7), 

2104008030 (15/20.4 using Table 7), 

2104008050 (12/19.6), 

2104008052: not there, so use same as 2104008050 (12/19.6), 

Same for 2104008053 

CASE 5: Alabama for which there is both broad and detailed woodstove SCCs

This case is unique because VOC is only in 2104008000 but PM2.5 (and HAPs) are in that SCC 

and numerous others

state_abbr Scc data_source PM2_5 VOC 

AL 2104008000 S-02-X 216.46 54987.12

AL 2104008002 S-02-X 1505.05 

AL 2104008003 S-02-X 59.76 

AL 2104008004 S-02-X 25.1 

AL 2104008010 S-02-X 2085.44 

AL 2104008030 S-02-X 34.67 

AL 2104008050 S-02-X 82.8 

I examined county-level inventory and it looks like the above is the pattern in very county. 

Examples: 
A-6

fips Scc poll ann_emis pm ratio 

1001 2104008000 PM2_5 2.05 0.089716

1001 2104008002 PM2_5 10.55 0.461707

1001 2104008003 PM2_5 0.42 0.018381

1001 2104008004 PM2_5 0.18 0.007877

1001 2104008010 PM2_5 9.13 0.399562

1001 2104008030 PM2_5 0.15 0.006565

1001 2104008050 PM2_5 0.37 0.016193

fips Scc poll ann_emis PM ratio 

1013 2104008000 PM2_5 0.77 0.028742

1013 2104008002 PM2_5 8.42 0.314296

1013 2104008003 PM2_5 0.33 0.012318

1013 2104008004 PM2_5 0.14 0.005226

1013 2104008010 PM2_5 16.22 0.60545

1013 2104008030 PM2_5 0.27 0.010078

1013 2104008050 PM2_5 0.64 0.02389

26.79

Approach is to remove current VOC from all counties and replace with VOC based on PM2.5 

and the following PM2.5 to VOC ratios 

The ratios to use: (by SCC) are in column 5 

 scc Ratio based on PM2_5 factor num 

and denom 

Factor sum 

AL 2104008000 FP: NEI documentation2

Table 1 for PM2.5 and 

corrected VOC EF of 18.9 

lb/ton 

216.46 (18.9/23.6) 0.80084746 173.3514

AL 2104008002 NEI documentation Table 

5 

1505.05 (53/30.6) 1.73202614 2606.786

AL 2104008003 NEI documentation Table 

6 

59.76 (12/19.6) 0.6122449 36.58776

AL 2104008004 NEI documentation Table 

7 

25.1 15/20.4 0.73529412 18.45588

AL 2104008010 NEI documentation Table 

5 

2085.44 (53/30.6) 1.73202614 3612.037

AL 2104008030 NEI documentation Table 

7 

34.67 15/20.4 0.73529412 25.49265

AL 2104008050 NEI documentation Table 

6 

82.8 12/19.6 0.6122449 50.69388

Grand total 6523.404

 

2

ftp://ftp.epa.gov/EmisInventory/2002finalnei/documentation/nonpoint/2002nei_final_nonpoint_documentation0206

version.pdf Appendix A. Residential Heating Using Wood 
A-7

Case 6. SC, where VOC mass missing from some SCCs.

State SCC

Data source 

code PM2.5 VOC

SC 2104008001 S-02-X 157.93 43268.9

 2104008002 S-02-X 1667.88 

 2104008003 S-02-X 66.21 

 2104008004 S-02-X 27.79 

 2104008010 S-02-X 3163.31 5478.91

 2104008030 S-02-X 52.73 38.74

 2104008050 S-02-X 125.57 76.85

Compute VOC from 2104008002, 2104008003 & 2104008004 

Using VOC to PM2.5 factors as follows: 

For 2104008002, use (53/30.6) 

For 2104008003 use (12/19.6), 

For 2104008004 use (15/20.4) 

Recompute VOC from 2104008001 as follows (case 1) 

VOCcorrected=VOCold*(EFcorrected/EFold) 

Where EFcorrected=18.9 lbs VOC/tons of wood burned. 

And EFold=229 lbs VOC/tons of wood burned. 

Case 7 -- SCC=2104008053 from Oregon and Washoe County (Nevada) 

Multiply PM2.5 by (12/19.6) 

Case 8 -- Selected New Jersey Counties 

For counties of Bergen, Essex, Hudson, Middlesex and Union , 

 VOC corrected = (18.9/229) * VOC old 

ie, treat these as Case 1 counties. 

Case 9 -- Selected Washington Counties 

For counties of King (53-033), Kitsap(-035), Pierce (-053), and Snohomish (-061), 

calculate new VOC as in Case 3 . 
B-1

Appendix B: Methodology to Speciate Partially-Speciated 

MOVES PM2.5 Emissions 

Approach to adapt partially-speciated gasoline emissions from the draft MOVES model to 

air quality modeling species needed for CMAQ. 

The MOVES output provided three components of PM2.5: two pre-speciated components of 

PM2.5 which are: 1) PEC, and 2) PSO4, and a a non-speciated component termed “PM25OC”, 

which is defined as the difference between total PM2.5 and PEC. 

It is important to note that PM25OC is not organic carbon, but is defined as the following: 

 MOVES total PM2.5 = PEC + PM25OC (1)

The CMAQ PM2.5 species were computed from (1) the MOVES output pollutants: PEC, PSO4 

and PM25OC, and (2) the speciation profile for total PM2.5 exhaust. The equations used are 

presented below. Since we had to adjust the PEC and POC emissions at 72 F to reflect the 

impact of colder actual temperatures prior to computing all of the species, the implementation of 

the equations does not follow the order presented. The order is described after the list of 

equations is presented. 

MOVES total PM2.5 is the sum of the two pre-speciated components of PM2.5 and a remainder 

term, R. 

 MOVES total PM2.5 = PEC + PSO4 + R (2)

The remainder term can be computed from the MOVES outputs of PM25OC and PSO4 as 

R = PM25OC - PSO4 (3)

 The R term includes POM, which consists of POC and the hydrogen and oxygen atoms attached 

to the carbon as part of the organic matter, PNO3, soil oxides and metals (also known as 

“crustal” and called METAL here), ammonium, and water, and thus can be also written as: 

R = POM + PNO3 + METAL + NH4 + H20 (4)

To correctly calculate the five PM2.5 species needed for CMAQ, we first needed to break out the 

POC, PNO3, and PMFINE from R. We used the proportional relationship of known species to 

unknown species from the speciation profile for exhaust PM2.5 for gasoline vehicles. All 

gasoline vehicles (e.g., Light Duty and Heavy Duty) use the same speciation profile for exhaust 

PM2.5, 92050: “Onroad Gasoline Exhaust – Simplified”. This simplified profile is based on 

Composite profile 91022. Fractions of PNO3 and PEC can be obtained from either the detailed 

or composite profile (they are the same). The detailed composite profile is required in order to 

determine the METAL component in equation (4) since metal fractions are not included in the 
B-2

simplified profile. Profiles 92050 and 91022 are in version 4.0 of SPECIATE (Hsu et al., 2006), 

which can be downloaded at www.epa.gov/ttn/chief/software/speciate/ 

We computed the primary nitrate based on the ratio of nitrate to elemental carbon from 

speciation profile 91022 using equation (5) shown below.

 PNO3 = PEC × FNO3 / FEC (5) 

where, 

FEC = Fraction of elemental carbon in speciation profile 91022= 20.801136%

FNO3 = Fraction of nitrate in speciation profile 91022 = 0.1015%

Since CMAQ’s PMFINE species is the sum of soil oxides, metals, ammonium, and water, we 

needed to calculate all of its components. First, the metals and ammonium are computed using 

equations (6) and (7). Equation (7) is based on stoichiometric calculations. 

 METAL = PEC× Fmetal / FEC (6) 

NH4 = (PNO3/MWNO3 +2 × PSO4/MWSO4) × MWNH4 (7)

where, 

Fmetal = Fraction of metals in speciation profile 91022 = (2.2256 %3

) 

FEC = Fraction of elemental carbon in speciation profile 91022= 20.801136%

MWSO4 = Molecular weight of sulfate (96.0576) 

MWNO3 = Molecular weight of nitrate (62.0049) 

MWNH4 = Molecular weight of ammonium (18.0383)

The final component of PMFINE is the non-carbon mass of organic carbon. To calculate the 

non-carbon mass, we first needed to compute organic carbon from the remainder term, R. 

A key assumption is that POM is a factor of 1.2 greater than the mass of primary organic carbon, 

which is also used in the CMAQ postprocessing software at EPA. 

POM = 1.2 × POC (8)

Using this assumption and assuming that the H20 is negligible, the equation needed for the 

calculation of POC is shown in equation (9) below. 

 POC = 5/6 × (R – METAL – NH4 – PNO3) (9) 

From equation (8), the non-carbon portion of the organic carbon matter is 20%, of the POC. By 

definition, PMFINE is the sum of the non-carbon portion of the mass, METAL and NH4. 

 

3

 To obtain this, all metals and other ions (e.g., Chlorine) with the exceptions of nitrate and ammonium were 

identified in the profile and the percentages were summed to give a total “METAL” percentage. 
B-3

 PMFINE = METAL + NH4 + 0.2 × POC (10)

For mobile sources, we assumed that PMC is 8.6% of the PM2.5 mass. 

 PMC = 0.086 × (PMFINE + PEC + POC + PSO4 + PNO3) (11) 

Order of Computations due to Temperature Adjustments

Due to the need to account for the impact of temperature on exhaust PEC and 

POC, some of the equations above were not implemented until after the 

temperature-adjusted PEC and POC were computed (after the spatial allocation 

and temporal allocation steps in SMOKE). 

The input emissions to SMOKE and equations or MOVES outputs used to create 

them from the MOVES data are listed below. The pollutant name in SMOKE 

inventory file is italicized. 

The following PM2.5 inventory “pollutants” were computed for input into 

SMOKE. 

1. PEC_72 (not computed, this is directly output from MOVES) 

2. PSO4 (not computed, this is directly output from MOVES)

3. PNO3 (computed from Equation 5) 

4. POC_72 (computed from Equation 9) 

5. OTHER = NH4 + METAL (computed from Equations 6 and 7) 

Temperature adjustments were applied by hour and grid cell to the PEC_72 and 

POC_72 in the SMOKE intermediate files (prior to the final merge) using a 

Lookup Table (see Table A-1). Note that the same lookup table was used to 

adjust PEC_72 and POC_72. 

The other CMAQ PM2.5 species at actual temperatures were created as follows: 

PMFINE = OTHER + 0.2 × POC (computed from Equation 10) 

PMC = 0.86 x (PMFINE + PEC + POC + PSO4 + PNO3) (computed from 

Equation 11) 

A final merge of all sectors was then done. 
B-4

Table A-1. Correction Factors to Adjust 72 F PM OC and EC Emissions for colder 

temperatures (supplied by Harvey Michaels, OTAQ, 9/5/2008) 

 

Year 

Temperature 

(degrees F) 

Correction Factor for Running 

Exhaust Correction Factor for Start Exhaust 

2005 -20 18.6454 70.7816 

2005 -19 18.0618 67.5797 

2005 -18 17.4965 64.5218 

2005 -17 16.9488 61.6025 

2005 -16 16.4183 58.8153 

2005 -15 15.9045 56.1542 

2005 -14 15.4067 53.6136 

2005 -13 14.9244 51.1878 

2005 -12 14.4573 48.8719 

2005 -11 14.0048 46.6607 

2005 -10 13.5665 44.5495 

2005 -9 13.1418 42.5339 

2005 -8 12.7305 40.6095 

2005 -7 12.332 38.7722 

2005 -6 11.9461 37.018 

2005 -5 11.5721 35.3431 

2005 -4 11.2099 33.744 

2005 -3 10.8591 32.2173 

2005 -2 10.5192 30.7596 

2005 -1 10.1899 29.3679 

2005 0 9.87099 28.0392 

2005 1 9.56203 26.7706 

2005 2 9.26275 25.5594 

2005 3 8.97281 24.4029 

2005 4 8.69197 23.2988 

2005 5 8.41992 22.2447 

2005 6 8.15638 21.2382 

2005 7 7.90109 20.2773 

2005 8 7.65378 19.3599 

2005 9 7.41422 18.484 

2005 10 7.18216 17.6477 

2005 11 6.95736 16.8492 

2005 12 6.73959 16.0868 

2005 13 6.52865 15.359 

2005 14 6.3243 14.6641 

2005 15 6.12635 14.0006 

2005 16 5.9346 13.3672 

2005 17 5.74885 12.7624 

2005 18 5.56891 12.1849 

2005 19 5.39461 11.6337 

2005 20 5.22576 11.1073 

2005 21 5.06219 10.6048 

2005 22 4.90375 10.125 

2005 23 4.75026 9.66683 

2005 24 4.60158 9.22946 

2005 25 4.45755 8.81189 

2005 26 4.31803 8.41321 

2005 27 4.18288 8.03256 

2005 28 4.05196 7.6691 

2005 29 3.92513 7.32215 

2005 30 3.80228 6.99088 

2005 31 3.68327 6.67456 
B-5

Table A-1. Correction Factors to Adjust 72 F PM OC and EC Emissions for colder 

temperatures (supplied by Harvey Michaels, OTAQ, 9/5/2008) 

2005 32 3.56798 6.37257 

2005 33 3.4563 6.08424 

2005 34 3.34812 5.80897 

2005 35 3.24333 5.54614 

2005 36 3.14181 5.29521 

2005 37 3.04347 5.05563 

2005 38 2.94821 4.82689 

2005 39 2.85593 4.6085 

2005 40 2.76655 4.39999 

2005 41 2.67995 4.20091 

2005 42 2.59607 4.01085 

2005 43 2.51481 3.82938 

2005 44 2.4361 3.65612 

2005 45 2.35985 3.4907 

2005 46 2.28599 3.33277 

2005 47 2.21444 3.18198 

2005 48 2.14513 3.03801 

2005 49 2.07799 2.90055 

2005 50 2.01295 2.76932 

2005 51 1.94994 2.64403 

2005 52 1.88891 2.5244 

2005 53 1.82979 2.41018 

2005 54 1.77252 2.30114 

2005 55 1.71704 2.19702 

2005 56 1.66329 2.09762 

2005 57 1.61123 2.00271 

2005 58 1.5608 1.9121 

2005 59 1.51195 1.82559 

2005 60 1.46463 1.74299 

2005 61 1.41878 1.66413 

2005 62 1.37438 1.58883 

2005 63 1.33136 1.51695 

2005 64 1.28969 1.44832 

2005 65 1.24932 1.38279 

2005 66 1.21022 1.32022 

2005 67 1.17234 1.26049 

2005 68 1.13564 1.20346 

2005 69 1.1001 1.14901 

2005 70 1.06567 1.09703 

2005 71 1.03231 1.04739 

2005 72 1 1 
B-6