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Wellness

Extreme UV levels: How harmful is it? How can you protect yourself against exposure?

Skin cancer or melanoma, skin ageing, cataracts and other eye issues could develop under prolonged UV exposure. Here's what you can do to protect yourself when the UV levels shoot up.

Extreme UV levels: How harmful is it? How can you protect yourself against exposure?

(Photo: iStock/Pheelings Media)

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If you have the suspicion that the weather is out to get us these few weeks, you might be right. The National Environment Agency (NEA) recently advised getting extra UV protection for the eyes and skin after the ultraviolet (UV) index in Singapore hit extreme levels.

On Wednesday (May 27), the index registered a reading of 11 and entered the extreme band at about 12.15pm. It climbed to a high of 12 at about 1.15pm before going down to 10 at 2.45pm on the same day. As of Thursday's latest reading at 1.15pm, it's at a very high level of 10.

But what exactly is the UV index? Does it have anything to do with the blistering temperature we’ve been having? More important, what should you be doing to protect yourself against UV exposure? Here’s a quick look:

WHAT IS THE UV INDEX?

It is an international standard index that describes the level of solar UV radiation on the earth’s surface, according to NEA, and ranges from 0 to 11+. The "low" end ranges from 0 to 2, while "Above 11" is described as "extreme". Basically, the higher the index reading, the more harmful it is for your eyes and skin.

(Photo: iStock/thebigland88)

HOW IS UV MEASURED?

In Singapore, the UV index is measured using a UVI sensor located in an open field at the Changi Meteorological Station, according to NEA. The data is reported hourly between 7am and 7pm on the NEA website. A few things can affect the reading, including rain, cloud cover and time of the day, which will be taken into account when determining the index reading.

DOES A HIGHER UV INDEX READING MEAN HOTTER TEMPERATURES?

Not necessarily. The sun produces different types of energy: There is visible light which we can see as sunlight; infrared radiation which we can feel as heat; and UV radiation which we cannot see or feel.

(Photo: iStock/Adennysyahputra)

Since UV is not tangible to us, it does not affect our surrounding temperature outside. In fact, UV radiation can be just as high on a cool day as it is on a hot one, especially if the sky is clear.

WHY SHOULD WE BE CONCERNED WITH UV?

First and foremost, melanoma. (Yes, Asians can get skin cancer, too.) Secondly, cataracts and other eye issues that can develop with prolonged UV exposure (which is also why sunglasses shouldn't just be fashion accessories). 

To drive home the importance of UV protection, here's a look at UV radiation. It is categorised by wavelength, which ranges from 100nm to 400nm, according to NEA. The shorter the wavelength, the more harmful the UV radiation:

UVA, 315nm to 400nm: UVA accounts for about 95 per cent of the UV radiation reaching us. It is responsible for the immediate tan you get when you’re out in the sun, skin ageing, wrinkling and the development of skin cancer.

(Photo: iStock/kali9)

UVB, 280nm to 315nm: The ozone in the atmosphere stops most UVB from reaching the earth’s surface but even so, about 15 per cent hits us. While this medium-length UV cannot penetrate beyond the superficial layers of skin, it is responsible for delayed tanning and burning. It can also lead to skin ageing and significantly promote skin cancer.

UVC, 100nm to 280nm: This is the most dangerous type of UV. Fortunately, the ozone absorbs all UVC and it does not reach the earth’s surface.

HOW COMMON ARE VERY HIGH UV LEVELS IN SINGAPORE?

According to NEA, it’s quite common for it to reach “very high” and “extreme” on the UV index between 11am and 3pm on days with little cloud cover. Rain and heavy clouds can help filter the UV radiation and lower it.

If you're looking at a particular time of the year, the UV levels are usually higher from February to April. 

SO WHAT SHOULD WE BE DOING TO TAKE CARE OF OURSELVES?

NEA has advised doing the following, particularly if you’re under the sun between 11am and 3pm:

  • Use sunscreen (at least SPF 30)
  • Use an umbrella and seek shade
  • Wear sunglasses that block UVA/UVB rays
  • Wear a broad-brimmed hat
(Photo: iStock/Marcelo Minka)

If you prefer a more specific breakdown, the United States Environmental Protection Agency has this: 

1-2: Low

You can safely stay outside with minimal sun protection such as sunglasses.

3-7: Moderate to high

Protection is needed. Seek shade if you need to go out between 11am and 4pm. Before heading outside, generously apply a broad-spectrum sunscreen (NEA recommends SPF 30 or higher) on exposed skin. Wear protective clothing, a wide-brimmed hat and sunglasses.

8+: Very high to extreme

Extra protection is needed as unprotected skin will burn. Avoid going out between 11am and 4pm. Otherwise, wear a generous amount of sunscreen (again, NEA advises SPF 30 and above), hat and sunglasses, and seek shade whenever your shadow is shorter than you.

Source: CNA/bk
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