(1) Previously, only the electricity sector and non-ferrous smelting industry were subject to the limits on nitrogen oxide and sulphide dioxide , two of the most notorious and significant contributors to smog.(2) The oxidizing fluxes usually include cupric oxide or manganese dioxide , which decompose at copper alloy melting temperatures to generate the oxygen required.(3) The clay body is held together firmly by the collapsed molecules of aluminum dioxide and silicon oxide, which intermesh like a basket weave.(4) High concentrations of nitrogen oxides, carbon monoxide, sulfur dioxides , and lead apparently often cancel the need for traditional blue.(5) Plastic production is water-intensive and causes air emissions of hydrocarbons, sulfur oxides, carbon monoxide, nitrogen oxides, and carbon dioxides .