UVA and UVB rays
Q) “What’s the difference between UVA and UVB rays?” – Liz, NSW
A) “Ultraviolet A (UVA) rays are the deepest penetrating UV rays that are associated with premature ageing and wrinkles. UVA reaches the earth surface at all hours of daylight – even on the most cloudy of days.
The wavelengths of UVA are long enough to allow some degree of curvature around the surface, which basically means that UVA from the sun at a horizon, dawn or dusk, can reach the skin.
The effects of UVA damage are cumulative and may contribute to DNA damage, as well as skin cancer. ”¨”¨Ultraviolet B (UVB) rays are the shorter wavelength rays that are responsible for the visible burn to the skin. UVB light reaches the surface at variable degrees throughout the day. Since the shorter wavelength does not allow bending like UVA, UVB is strongest when the sun is directly overhead. Therefore, UVB is typically most intense from 10am – 3pm (sometimes 9am – 4pm depending on Daylight Savings).”