All of these chemicals are very irritating and reactive so that they oxidize materials as well as lungs. A temperature inversion is an instance in which cold air is covered by warmer air. These have occured in Donora Penna. and London. The stratosphere is 12-50 km above the earth's surface. Air is thin, but radiation is intense causing molecules to break apart and free radical formation.
Ozone is normally in concentrations of a few ppm in the atmosphere.
It is measured by the amount of radiation that gets through to the earth. It has been measured since about 1880. There is also now a slight seasonal decrease in ozone in the northern hemisphere. These are used as solvents, refrigerants, foam blowing agents, etc. They are not very chemically reactive so they do not go through chemical combinations as does chlorine or chlorides from the ocean.