Download the woodworking calculator to help you estimate the releases of National Pollutant Release Inventory (NPRI) substances.

The substances of concern for woodworking are criteria air contaminants (CACs) and speciated volatile organic compounds (VOCs). These calculations relate to painting, natural gas consumption, and sawdust.

Calculate the total woodworking-related for each substance and process. Use the Material Safety Data Sheet (MSDS) to identify the VOC species released by various wood finishing activities.

The calculator focusses on releases to air and uses default emission factors. It can be adapted to use site-specific emission factors if they are available. If you want to use a site-specific emission factor, enter it in the emission factor column, but be sure to convert the units correctly. 

The spreadsheet calculators use emission factors based on uncontrolled emission sources. If you use an emission control device and the default emission factor is uncontrolled, use this formula to adjust the spreadsheet calculation:

Controlled emissions = uncontrolled emission x ((100 - control efficiency)/100)

Since NPRI reporting thresholds are for the facility as a whole, you may need to combine the air releases you calculate with releases from other sources at your facility.

The following sections explain how the spreadsheet calculator works.

Suggested estimation methodology for painting-related emissions: mass balance

Calculation for Part 4 VOC releases

A mass balance approach is recommended. Use this formula to calculate the mass of each product used:

M = (V x D)/1000


  • M = mass used [tonnes]
  • V = volume used [liters]
  • D = density [kg/liter]

Next, sum the mass of the volatile component of each product used.

E = (M x C)1 + (M x C)2 + …


M = mass used [tonnes]
C = % volatile organic compound (VOC)

Note: C and D are found on the product MSDS sheet


Suggested estimation methodology for releases from natural gas consumption: emission factor

The general equation for emissions estimation using an emission factor is:

E = A x EF


  • E = emissions
  • A = activity rate
  • EF = emission factor


N = amount of natural gas burned [million cubic meters]

If you know the amount of natural gas burned in gigajoules, use this equation to calculate the amount of natural gas burned in million cubic meters (m3):

N = H/0.0386/1000000

where, H is the amount of natural gas burned in gigajoules.

Calculation for Part 1 and Part 4 releases from combustion

E = (N x EF)/1000


  • E = emissions [tonnes]
  • N = amount of natural gas burned [million cubic meters]
  • EF = emissions factor

Substance releases

Part 4 criteria air contaminants (CAC) releases
Substance Chemical Abstracts Service Registry Number (CAS RN)Footnote 1  Part Emission Factor (EF)Footnote 2  EF units
Ammonia Footnote* 1 5.13E+01 kilograms (kg)/million m3
Carbon monoxide (CO) 630-08-0 4 1.35E+03 kg/million m3
Sulphur dioxide (SO2) 7446-09-5 4 9.61E+00 kg/million m3
Oxides of nitrogen (NOx), expressed as nitrogen dioxide (NO2) 11104-93-1 4 1.60E+03 kg/million m3
Volatile organic compounds (VOCs) Footnote* 4 8.81E+01 kg/million m3
Total particulate matter (TPM) Footnote* 4 3.04E+01 kg/million m3
Particulate matter less than or equal to 10 microns (PM10) Footnote* 4 3.04E+01 kg/million m3
Particulate matter less than or equal to 2.5 microns (PM2.5) Footnote* 4 3.04E+01 kg/million m3

Suggested estimation methodology for sawdust-related emissions: emission factor


Q = sawdust removed [tonnes]
R = removal efficiency of dust collectors [%]

Calculation for Part 4 Releases from dust collector releases

The equation to calculate the emissions is:

E = Q/R - Q

where, E is emissions in tonnes.

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