ULTRAVIOLET RADIATION

What is ultraviolet radiation (UVR)?

The energy from the sun comes to us in the form of visible radiation (light) and invisible radition such as infrared radiation (heat) and ultraviolet radiation.

Ultraviolet radiation can cause sunburns and can contribute to skin cancer.
UVA rays enter deep into the skin and may contribute to premature aging and
wrinkling of the skin and even to skin cancer. UVB rays do not enter as
deeply as UVA rays, but are more likely to cause sunburns and are primarily
responsible for causing skin cancer.

There are 3 forms of ultraviolet radiation: UVA, UVB and UVC.

What do I need to know about ultraviolet radiation(UVR)?

Many things effect the amount of ultraviolet radiation (UVR) that you are exposed to:

the temperature   •   how close you are to the equator   •   the time of the day
clouds   •   the time of the year   •   the way UVR scatters
they way UVR is reflected   •   your altitude   •   the ozone layer

The temperature

Ultraviolet radiation (UVR) levels are not usually related to temperature. UVR levels can be high even on cool days. UVR is usually at its highest around midday, while temperature is often highest in the late afternoon.

How close you are to the equator

The nearer a country is to the equator, the stronger the radiation from the sun.

The time of the day

The higher the sun is in the sky, the shorter the distance sunlight has to travel through the atmosphere. So UVR levels are highest from 11am–3 pm. This is usually not the hottest part of the day, which is later in the afternoon.

Clouds

Ultraviolet radiation can go through cloud. A cloudy day can reduce the level of ultraviolet radiation, but this can be as little as a 10% reduction. The UVR on a light overcast day can be similar to that of a cloud-free day.

The time of the year

In Ireland, ultraviolet exposure is greatest in the summer. But UVR reaches the earth every day of the year. So you should follow the Sun Smart Code every day.

The way UVR scatters

Solar UVR is made up of scattered and direct radiation. If there is a blue, cloudless sky and you are outside in the shade, you are still exposed to UVR. Sometimes the amount of scattered UVR may be greater than the amount from the direct sun.

The way UVR is reflected

UVR can be reflected back from some surfaces. Snow reflects the greatest amount. Sand, white paint, grass and water all reflect a considerable amount of ultraviolet radiation.

Your altitude

Higher altitudes receive more UVR because the thinner atmosphere filters less of the ultraviolet radiation. So you may get move UVR in the mountains than you do at the sea.

The ozone layer

Ozone is a form of oxygen that is present naturally in the upper atmosphere. The ozone layer absorbs most of the harmful ultraviolet rays. But the ozone layer has thinned in certain areas. This is called ozone depletion, and it increases the amount of UVR we get.

What is ozone depletion?

Ozone is a form of oxygen that is present naturally in the upper atmosphere. It can absorb UVC and UVB radiation. The ozone layer usually protects the earth from about 90% of the sun’s ultraviolet radiation. But industry and vehicle wastes, pollution and CFCs (chlorofluorocarbons) all make holes in the ozone layer. CFCs (chlorofluorocarbons) are used in a variety of industrial and household appliances such as aerosol sprays, fridge coolants and packing materials.

These holes in the ozone layer expand seasonally as the earth moves around the sun. In the northern hemisphere, where Europe is, the holes usually expand in the summer months. As a result, ultraviolet radiation, in particular UVC, can reach the earth without being filtered. So continued damage to the ozone layer means that there is more ultraviolet radiation at the earth’s surface. This increases your risk of skin cancer. The problem is more severe in the South Polar Region, which includes Australia.

Always follow the SunSmart Code to get protection from ultraviolet radiation.

Remember these points:

• Always apply a sunscreen with an SPF of 15 or higher and UVA protection 20 minutes before you go out in the sun. Reapply every 2 hours, even on cloudy days. Reapply sunscreen after swimming or perspiring.
• Wear wrap-around sunglasses that can prevent ultraviolet radiation from entering the eyes at the sides.
• Remember that the ultraviolet radiation can reflect back from some surfaces.
• Remember that if the temperature falls, the ultraviolet radiation levels can still be high.
• Children are unaware of the dangers of ultraviolet radiation. Always protect young children with suitable clothing, hats, sunglasses, sunscreen and shade.