• UVA (wavelength 320-400 nm) accounts for 95% of terrestrial radiation 

• UVB (wavelength 290 – 320 nm) accounts for the other 5% 

• Both cause photoaging, hyperpigmentation and skin cancer 

• UVB causes sun burn 

• UVB is strongest midday and in the warm months 

• UVA is relatively constant day round and year-round. 

• UVA is not filtered out by glass, but UVB is 

• SPF (sun protection factor) is the ratio of the amount of UV light required to cause sunburn on sunscreen protected skin to the amount required on unprotected skin 

• SPF protection is based on a 2mg/cm² thickness of application. Most consumers only apply .5 mg/cm² (a thinner layer) and therefore don’t receive the desired protection 

• Blocking agents are either organic (octinoxate, homosalate, octisalate, oxybenzone, avobenzone, ecamsule, ensulfizole) or inorganic (titanium dioxide and zinc oxide)  

• Octinoxate, homosalate, octisalate, and ensulfizole only block UVB 

• Zinc oxide and titanium dioxide block both UVA and UVB but zine offers better UVA protection 

• All organic sunscreens can cause allergic contact allergy especially oxybenzone 

• Organic sunscreens are absorbed systemically, and animal studies raise estrogen and lower testosterone levels 

• Oxybenzone has been shown to impact kidney function 

• Oxybenzone and octinoxate are detrimental to sea corals 

• UPF is ultraviolet protection fact of solar clothing 

• A UPF of 30-49 provides very good protection and a UPF of 50+ excellent protection