Sulfur dioxide belongs to the family of sulfur oxide gases.
Most SO 2 monitoring stations are located in urban areas. The highest monitored concentrations of SO 2 are recorded in the vicinity of large industrial facilities. Short-term exposures of asthmatic individuals to elevated SO 2 levels while at moderate exertion may result in reduced lung function that may be accompanied by such symptoms as wheezing, chest tightness, or shortness of breath. The subgroups of the population that may be affected under these conditions include individuals with cardiovascular disease or chronic lung disease, as well as children and the elderly. Sulfur dioxide also is a major precursor to PM-2.5, which is a significant health concern as well as a main pollutant that impairs visibility.