SO2 Sulfur Dioxide

Sulfur dioxide (SO₂) is a colorless, non-flammable gas with a pungent odor, often described as similar to the smell of burning sulfur. Specifically, it is primarily produced during the burning of sulfur-containing fuels, such as coal and oil. In addition, it is generated during industrial processes like metal smelting and petroleum refining. As a result, sulfur dioxide contributes to the formation of particulate matter (PM2.5) and fine aerosols, which can severely affect air quality. Given the health and environmental risks associated with sulfur dioxide, many countries regulate its emissions. For instance, in the U.S., the Environmental Protection Agency (EPA) sets limits on the amount of SO₂ that can be emitted by industries, and air quality standards are established to protect public health.