11
Pollution control equipment for the emission of mercury, gases and toxic waste; Installations and apparatus for controlling the collection, flow and emission of gases, mercury, pollution, emissions and toxic waste; heat exchangers for the removal of gases, mercury, pollution, emissions and toxic waste; activated carbon injection systems for the control of gases, mercury, pollution and emissions; dry sorbent injection systems for the control of gases, mercury, pollution and emissions; flue gas capturing and conditioning equipment; scrubbers [parts of gas installations]; filters for waste gas purification; filters for gas and fume extractors; filters for cleaning air; flues and installations for conveying exhaust gases; flue gas cleaning apparatus; flues and installations for conveying gases and emissions
37
Installation, maintenance, and repair of pollution control equipment; building construction and repair services related to pollution control systems
40
Chemical treatment of exhaust gases, mercury, pollution and emissions from fossil fuel combustion; treatment of hazardous gases and waste
42
Advisory services relating to pollution and emissions control; emissions control testing for the presence of pollutants; pollution and environmental control services