| Section2 = | Section4 = | Section7 = }} Ozone or trioxygen (O3)'s a triatomic molecule, consisting of three oxygen atoms. It's an allotrope of oxygen that's much less stable than the diatomic O2. Ground-level ozone's an air pollutant with harmful effects on the respiratory systems of animals. The ozone layer in the upper atmosphere filters potentially damaging ultraviolet light from reaching the Earth's surface. It's present in low concentrations throughout the Earth's atmosphere. It's many i… (More on Ozone)