What is UV Index

What is UV Index?

By SkinCabin

UV Index measures the intensity of UVA and UVB radiation from the sun. Higher the number, the higher the strength of the radiation reaching us.

Originally when the UV index was created, it was meant to have a value between 1 and 10. But now it has been recognised that its value can be higher than 10. This is mainly because of Australia. The UV index in Australia in the Summer months can be way higher than 10.

UV Index - What does it mean?

Extreme: 11 and above
Very High UV index: 8 to 10
High UV index: 6 to 7
Moderate UV index: 3 to 5
Low UV index: 1 to 2

UV Index and Sunscreen

Low UV index numbers can also cause harm to our skin - only the intensity of harm varies. Any number from 6 onwards is dangerous to the skin. Regular reapplication of sunscreen becomes essential. Please note that sunscreen is a must for every UV index value. It is just that the harm from UV index 6 onwards is severe if no sunscreen is used.

UV Index and Times

It is usually highest in the middle part of the day between 10 am and 2 pm.

You cannot see or feel UV radiation. It is not the heat you experience when you go out. It is invisible and silently causes harm. Just because the heat outside might feel less intense, don't assume it is safe to go out without sunscreen. Always remember that the heat you feel is not related to UV. So even when it does not feel very hot, the UV index can be high.

Temperature does not determine UV risk.

What is UV Index dependent On?
  • Time of the day: Higher in the middle part of the day (between 10 am and 2 pm)
  • Season: Higher in Summers than in Winters
  • Proximity to the Equator: Higher if the place you live in is closer to the equator
  • If you live in Australia: The ozone layer is very thin in Australia. The layer of ozone in the upper atmosphere absorbs a lot of UVB radiation. UVB radiation causes sunburn and skin cancer. In Australia, the ozone layer is very thin. And so the amount of UVB radiation reaching the surface is much higher in Australia. This is the reason you can get very quickly sunburnt in Australia.
  • Pollution: Pollution makes the air we breathe unpleasant. It does, however, serve as a blanket above the surface and reduces the UV index.

Where can you find the UV index?

The weather department in most countries publishes the UV index for various regions in their countries. These should be online as well. So search online for your region's information.

Next time you check the temperature, check the UV index as well. Equally important - strike that - Probably more important as far as your skin is concerned.

If you don't have the information, the shadow rule helps. Not accurate but better than nothing. If your shadow is smaller than your height, you are in high UV index time. This means frequent reapplication of sunscreen is needed.