The UV index measures the intensity of UV radiation.
UV radiation is the radiation from the Sun. There are three types of UV radiation from the Sun: UVA, UVB and UVC.
UVC does not reach the earth. So we don’t have to worry about UVC.
UVA and UVB are the ones that concern us. Both these types can cause skin cancer.
UVA can penetrate deep inside our skin, damage collagen, and thus age it. Collagen is the protein that gives our skin its structure.
UVB can destroy the good cells, leading to skin ageing. UVB is also responsible for the skin burn.
UV index scale
The UV index scale ranges from 0 to 11+. The higher the number, the more harm the radiation can cause to our skin.
Below, I have given a quick overview of what the various numbers mean:
Protection includes sunscreen, reapplying sunscreen at regular intervals, sun hat and sunglasses. If you are in the water, wear protective swimwear.
What does the UV index depend on?
It depends on the time of the day, weather and the location.
The UV index is usually highest between 10 am and 2 pm.
Altitude plays a significant role in UV radiation, with levels increasing as you move to higher elevations.
The closer the location is to the equator, the higher the UV index is.
If it is a cloudy day, some of this radiation is blocked, resulting in a lower UV index than on a clear sky day.
Surfaces like water, snow, sand, and concrete reflect UV rays, increasing the intensity of UV radiation.
Australia may not be close to the equator, but its UV index is still high. This is because the ozone layer above Australia is not very thick. A thick ozone layer effectively absorbs some harmful UV radiation, whereas a thinner ozone layer allows more radiation to reach the Earth.
Checking the UV index before planning outdoor activities is a simple yet effective way to avoid peak UV hours.
One quick reminder: If you don’t feel the heat, don’t assume that the index is low at that time. The heat is from the sun’s infrared radiation. The UV index measures the sun’s ultraviolet radiation, which harms our skin.
It is important to remember that you can’t feel the UV radiation. So, please don’t use the heat you feel to indicate its intensity.
Shadow rule
Here is a tip that can help you determine the intensity of the UV radiation at a given point in time…
If your shadow is smaller than your height, the radiation is intense. The smaller the shadow, the higher the intensity.
Remember, this tip is a guide, not a definitive measure. It’s especially useful when you can’t access the UV index in your area.