gaseous discharges containing solid, liquid or gaseous emissions; their volumetric flow rates shall be expressed in cubic metres per hour at standard temperature (273 K) and pressure (101,3 kPa) after correction for the water vapour content, hereinafter referred to as (Nm3h), off-gas - the gas produced as a byproduct of pyrolysis of solids in which the major objective is usually to produce fuel oil, oil, and char