Fossil fuel percent of [its] weighted emissions in 1998. Combustion of fossil fuels also produces other air pollutants, such as nitrogen oxides, sulfur dioxide, volatile organic compounds and heavy metals. According to Environment Canada: "The electricity sector is unique among industrial sectors in its very large contribution to emissions associated with nearly all air issues. Electricity generation produces a large share of Canadian nitrogen oxides and sulphur dioxide emissions, which contribute to smog and acid rain and the formation of fine particulate matter. It is the largest uncontrolled industrial source of mercury emissions in Canada. Fossil fuel-fired electric power plants also emit
Nitrogen dioxide is a consequence of preferential absorption of light in the blue (400 – 500 nm), although the absorption extends throughout the visible (at shorter wavelengths) and into the infrared (at longer wavelengths). Absorption of light at wavelengths shorter than about 400 nm results in photolysis (to form NO + O, atomic oxygen); in the atmosphere the addition of O atom so formed to O results in ozone formation. Nitrogen dioxide typically arises via the oxidation of nitric oxide by oxygen in air: Nitrogen dioxide is formed in most combustion processes using air as the oxidant. At elevated temperatures nitrogen combines