Q: What’s the difference between the different types of UV rays?
A: There are three types of UV rays; UVA, UVB and UVC. Fortunately UVC rays are blocked by the ozone layer; however UVA and UVB penetrate to the earth surface.
UVA rays account for up to 95% of the UV radiation reaching the Earth’s surface. UVA rays are present during all daylight hours and can penetrate glass and clouds. UVA penetrates the skin more deeply than UVB causing cumulative DNA damage that over time results in photo-aged skin and skin cancer.
UVB rays damage the skin’s more superficial layers causing sunburns. The intensity of UVB rays vary depending on the season and time of day (10 am to 4 pm are the peak hours) and UVB rays also play a key role in the development of skin cancer.
Remember that UVA rays are present even on the most cloudy days, and penetrate glass. That is why it is important to wear your “broad spectrum” sunscreen on cloudy days, while skiing or snowboarding, and indoors if you work near a window.