When you take in a breath of air you probably aren't aware of everything you just breathed in. I don't mean all of the dust, pollen, bugs or other things like that. I mean the chemicals naturally present in air.
Air is actually a mixture of several different elements and compounds.
There is almost four times as much nitrogen as oxygen. Helium can be used to inflate balloons so that they float in the air. Carbon dioxide comes from the breathing of almost all living organisms and from anything that burns. Like carbon dioxide, carbon monoxide also comes from burning. Ozone helps protect us from the type of sunlight that causes sunburns.