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. Ozone has a very unique smell that you may have noticed after a thunderstorm that had lots of lightning. You don't normally smell ozone because it is too high in atmosphere for us to smell. Chlorofluorocarbons have received much attention lately since many scientists believe that they help destroy the protective ozone present in air.