In a way, air conditioning has changed the environment. Early air conditioners used fluids that were harmful to the environment, a type of chlorofluorocarbons (CFCs). Nowadays, air conditioners are...
Older units used Ozone depleting refrigerants, which had chloro floro carbons. (CFC)
New units now have Ozone friendly refrigerants, which are hydro floro carbons. (HFC)