Sulfur dioxide (SO2) is an inorganic compound that exists as a colorless gas or liquid with a strong, choking odor. It is produced in large quantities in intermediate steps of sulfuric acid manufacture and is a heavy, colorless, poisonous gas. Here are some key points about SO2:

• Structure and bonding: SO2 is a bent molecule with C2v symmetry point group. It has a bent shape due to the lone pair of electrons on the sulfur atom. The bonding in SO2 can be described in terms of resonance between two resonance structures.

• Uses: The overarching, dominant use of sulfur dioxide is in the production of sulfuric acid. It is also used as a disinfectant, a refrigerant, a reducing agent, a bleach, and a food preservative, especially in dried fruits.

• Sources: SO2 is released naturally by volcanic activity and is produced as a by-product of copper extraction and the burning of sulfur-bearing fossil fuels. The largest sources of SO2 emissions are from fossil fuel combustion at power plants and other industrial facilities.

• Health effects: Short-term exposures to SO2 can harm the human respiratory system and make breathing difficult. People with asthma, particularly children, are especially sensitive to these effects of SO2. Long-term exposure to SO2 can cause respiratory illness, aggravate existing heart disease, and cause eye, nose, and throat irritation.

• Environmental effects: SO2 can affect the environment by contributing to acid rain, which can harm trees, lakes, and other sensitive ecosystems. It can also contribute to the formation of fine particulate matter, which can harm human health.

• Exposure: People can be exposed to SO2 by breathing it in the air or getting it on their skin. People who live near industrial sources of sulfur dioxide may be exposed to it in the air. People are most likely to be exposed if they work in industries where SO2 is produced, such as copper smelting or power plants, or where it is used in the production of sulfuric acid, paper, food preservatives, or fertilizers.

• Prevention: Limiting outdoor activities when air pollution levels are high can help prevent exposure to SO2. The EPA and the Wisconsin Department of Natural Resources (DNR) issue air quality alerts for high pollution days. People with existing respiratory difficulties, such as asthma, should pay special attention to these alerts.