Sulphur oxides are a group of substances and the most common is sulphur dioxide with the chemical name SO2. SO2 is a colourless gas with a penetrating, chocking odour. It dissolves readily in water to form an acidic solution – sulphurous acid.
Common name: Sulphur and Sulphur dioxide, SOx.
Sulphur dioxide is used for bleaching wool, as a disinfectant, as a fumigant in pest control and as food preservative. Liquid sulphur dioxide is been used in purifying petroleum products.
Releases to the environment
The main source of sulphur dioxide is the burning of fossil fuels. Power stations, oil refineries and other large industrial plants releases around 90% of the total mass released. Motor vehicles and domestic boilers release sulphur dioxide and active volcanoes and forest fires produce it naturally. From 1970 to 1998 the emission of sulphur dioxide has been reduced by 75% in Europe. This reduction was largely a result of the decreasing use of coal for power generation and its replacement by natural gas.
Impacts on the environment and human health
Sulphur dioxide dissolves in the water droplets in clouds causing the rain to be more acidic than usual. Acid rain affects the natural balance of rivers, lakes and soils, resulting in damage to wildlife and vegetation. Emitted in sufficient quantities at low or ground level combined with air moisture can cause gradual damage to some building materials. Excessive exposure to sulphur dioxide may cause health effects on the eye, lung and throat.
Sulphur oxides are controlled by the Gothenburg Protocol under the Geneva Convention on Long-Range Transboundary Air Pollution and the EU NEC (National Emission Ceiling) directive especially on sulphur dioxide, nitrogen oxides, hydrocarbons and ammonia. Furthermore sulphur oxides are on the EU-Commissions EPER list and listed in the PRTR Protocol under the Århus Convention.
CAS NO: 05-09-46 for sulphur dioxide.