Sun radiates a spectrum of Electromagnetic Radiation (EMR)
Parts of EMR correspond to energy required to break chemical bonds
eg DNA
Leads to gene damage and skin cancer
Most damaging is UV
Sunscreens absorb high energy UV
Often contain Benzene rings
Ozone absorbs UV very well
Includes UV-B and UV-C
Ozone is a pollutant at ground level
Photochemical smog