The incineration process consists of burning solid, semisolid, liquid, or gaseous waste to produce carbon dioxide, water, and ash. It is an efficient means of reducing waste volume and recovering energy. The solid, incombustible residue of incineration is inert, sanitary and sensibly odourless. Incineration contributes to air pollution. The polluting emissions are ash, hydrocarbons, sulfur oxides (SOx), nitrous oxides (NOx), chlorides, and carbon monoxide. Estimating absolute quantities of these pollutants is not an exact science, but historical testing data from typical incinerators allow estimates of emissions to be made. Measurement methods for incinerator emissions are sufficiently advanced to permit actual data to be obtained for any existing incinerator. These measurements are preferred in all cases over analytical estimates