3. Emission factors

Measurements are taken in the flue gas, at the outlet of heating appliances, and are usually expressed in terms of volume content on dry flue gas: parts per million (ppm) or percent (%). From these measurements, it is possible to express the values in different units, the most common being :

• mg · Nm ^–3 , a unit used to check regulatory thresholds: mass of pollutant per normal cubic metre of dry smoke;

• g · GJ ^–1 , an emission factor used to compare the pollution of different energy sources for...