Amount of acidifying gases, weighted according to their acidifying effect. The total emission of acidifying gases is estimated by adding the emissions of each gas in acid equivalents. The following factors are used to convert the acidifying gases to acid equivalents (Potential Acid Equivalents):

Nitrogen oxides (NO_X): 1/46
Sulphur dioxides (SO₂): 1/32
Ammonia (NH₃): 1/17