Determining the Pollutant Emission Rate from a Source

The emission rate of a pollutant is the product of the measured pollutant concentration and the measured effluent flow rate. In order to make this work, the volume must be expressed in Reference or Standard Conditions.

Pollutant Concentration (mg/R.m³) x Effluent Flow Rate (R.m³/s) = Pollutant Mass Rate mg/s

Volumes and volumetric rates measured at Actual Conditions (A) can be converted to Reference or Standard Conditions using the universal gas laws.

Instrumental analyzers typically report pollutant concentrations on a part per million volume basis (ppmv). This unit needs to be converted to a mass per unit volume basis (mg/m³) in order to determine the mass rate of the pollutant.

This is accomplished using the formula below:

MW is the molecular weight of the pollutant gas i.e. 64 g/mole for SO2
MV is the molar volume at reference or standard conditions i.e. 24.45 L/mole at 25°C and 1 atm

In Canada, reference conditions (R) are 25°C and 101.3 kPa.  In the United States, standard conditions (S) are 68°F and 29.92 in Hg. 


For more detailed information on the calculation of pollutant emission rate, please contact:

Michael Denomme

Peter Pakalnis

Source Testing Source Testing (44 KB)