Ultraviolet (UV) radiation is a type of energy produced by the sun and some artificial sources, such as arc welders and solariums.
The sun’s UV is the main cause of skin cancer. Too much UV exposure also causes sunburn, tanning, premature ageing and eye damage.
You can see the sun’s light. You can feel the sun’s heat. But you can’t see or feel the sun’s UV radiation. UV can reach you directly from the sun. It can also be reflected off different surfaces and scattered by particles in the air.
Your senses cannot detect UV radiation, so you won’t notice it is all around you and you won’t notice any skin damage until it has been done.
The UV Index
The World Health Organization's Global Solar UV Index measures UV levels on a scale from 0 (Low) to 11+ (Extreme). Sun protection is recommended when UV levels are 3 (Moderate) or higher.
The UV level is affected by a number of factors including the time of day, time of year, cloud cover, altitude, location and surrounding surfaces.
The UV Index and the sun protection times
The sun protection times are issued when UV levels are forecast to be 3 or higher. At this level there is a risk of skin damage for most Australians.
You can find the sun protection times for your location:
During the sun protection times, protect your skin and eyes by using covering clothing, sunscreen, a hat, shade and sunglasses. Don’t just wait for hot and sunny weather.
Some people (such as transplant recipient patients, people with compromised immune systems and genetic skin cancer risk) are at high risk of skin cancer and may require additional sun protection and early detection strategies specific to their health needs. Please consult your doctor for specific health advice.
Is temperature related to UV?
UV is not hot. It can't be felt and isn't connected to the temperature. UV levels can be damaging on cool, cloudy days and warm, sunny days.
UV is always highest during the middle part of the day between 10am and 2pm (or 11am and 3pm daylight saving time).
The temperature can peak in the afternoon when UV levels are less intense.
Why is the UV so high in Australia?
Australia experiences some of the highest levels of UV in the world.
Different factors affect our UV levels including:
- location: UV levels are highest along the equator. Australia is near the equator so we experience high UV levels
- time of year: our elliptical orbit around the sun and our axial tilt combine to ensure that we are closer to the sun in our summer than the northern hemisphere e.g. in summer the UK has UV Index 6–8, while Australia has UV Index 10–14
- we have clear skies and less air pollution.
How does UV add up?
UV damage is accumulative. Your skin remembers and records all the UV exposure over the years which contributes to your long-term risk of skin cancer. The more UV you’re exposed to, the greater your risk. That’s why it's important for outdoor workers to protect their skin all year round. Even low UV levels can be harmful when exposed for long periods.
Health effects of too much UV radiation
Too much UV radiation can cause skin and eye damage, sunburn, tanning and skin cancer.
Sunburn is a UV radiation burn to the skin. In Victoria's summer months, skin can burn in as little as 11 minutes and can take days or weeks to heal. Mild sunburn can be treated at home, but you should see a doctor immediately for severe and/or blistered burns. Find out more about sunburn treatment at Better Health Channel.
While the signs of a sunburn fade with time, the damage can’t be undone and adds to your lifetime tally of UV damage, which increases your risk of skin cancer.
Sunburn prevention is best. Always check the sun protection times on the free SunSmart app and use a combination of sun protection measures when required.
UV damage can cause different eye conditions including:
- photoconjunctivitis: inflammation of the conjunctiva – the membrane lining the inside of the eyelids and eye socket, which is also known as snow blindness or welder's flash
- photokeratitis: inflammation of the cornea
- macular degeneration: damage to the retina
- cataracts: clouding of the lens
- pterygiums: tissue growth on the cornea
- skin cancer of the conjunctiva and skin surrounding the eye.
Up to 80% of fine lines and wrinkles are the result of UV damage. UV also causes skin sagging, blotchiness and roughness.
Photosensitivity is extreme sensitivity of the skin or eyes to UV radiation. This means the skin can burn more easily, increasing your risk of skin cancer.
Photosensitivity is caused by ingesting, inhaling or skin contact with photosensitisers – substances that cause photosensitivity. Photosensitisers include industrial chemicals, drugs, plants and some essential oils and fragrances. Some medications can also cause photosensitivity. Check with your doctor or pharmacist, as alternate medication may be available.
Information on substances which cause photosensitivity can be found in the Guide on exposure to solar ultraviolet radiation (UVR) from Safe Work Australia.