Stratospheric ozone limits the amount of harmful ultraviolet light that reaches Earth.
See Wavelengths for information on how to write about ultraviolet light.
Use lower case for terms relating to atmospheric ozone, even if they have capitalised abbreviations, but add an s to abbreviations:
ozone-depleting substances (ODSs) chlorofluorocarbons (CFCs) photochemical oxidants
Reminder. Just because the abbreviation of a term is made up of capitals, it does not mean that the term has initial capitals when it is spelt out.