Here are four different ways chemists use to show a molecule of sulfur dioxide. In the colored molecule models, sulfur is yellow and oxygen is red. Click on image for full size (26 Kb GIF) Windows to the Universe original artwork by Randy Russell.

Here are four different ways chemists use to show a molecule of sulfur trioxide. Click on image for full size (29 Kb GIF) Windows to the Universe original artwork by Randy Russell.

Sulfur dioxide (SO₂) and sulfur trioxide (SO₃) are two kinds of chemicals. They both have sulfur and oxygen atoms in them. They also are also part of some kinds of air pollution. Scientists use the term "sulfur oxides" when they want to talk about both of these chemicals at once.

Earth's atmosphere has some sulfur oxides in it. Some of the sulfur oxides in the air come from nature. For example, some of it comes from volcanoes. Some of the sulfur oxides in the air are created by people and the things we do. Coal and oil have a bit of sulfur in them. We burn coal and oil to make electricity and heat. When the coal and oil burn, the sulfur in them combines with oxygen in the air to make sulfur oxides.

Sulfur dioxide pollutes the air. It is bad for your lungs and makes it hard to breath. Sulfur oxides also help make acid rain. Sulfur dioxide gets together with water droplets in the air to make sulfuric acid. Sulfuric acid is part of acid rain. Acid rain is bad for plants and fish and other living things.