UVA vs UVB: Understanding UV Light

Ultraviolet radiation is part of the energy emitted by the sun. It is also produced by artificial sources, including sunbeds. UV is different from the warmth you feel outdoors.

What are UVA, UVB and UVC?

• UVA reaches deeper into the skin and contributes to skin ageing.
• UVB mainly affects the outer skin layers and causes most sunburn.
• Solar UVC is filtered by the atmosphere before it reaches the ground.

The World Health Organization's UV overview explains these differences. Both UVA and UVB can contribute to skin cancer, as explained by Cancer Research UK.

What changes UV levels?

UV varies with the time of day, season, location, altitude and cloud cover. Reflections from surfaces such as water and sand also affect exposure. The WHO ultraviolet radiation factsheet recommends sun protection when the UV index reaches 3.

Read how skin tans, sunbed risk information and outdoor sun protection guidance.

Information checked against the linked sources on 2 October 2026.