戰勝曬傷：今夏智勝紫外線的實用小技巧！

UV levels are a way to measure how strong the sun's ultraviolet rays are at any given time. Ultraviolet, or UV, radiation comes from the sun and passes through the Earth's atmosphere. While some UV exposure is good for us because it helps our bodies make vitamin D, too much can be dangerous. High UV levels can damage our skin, cause sunburn, and even lead to skin cancer. That is why it is important to understand what UV is, how it is measured, and how to protect yourself when UV levels are high.

UV radiation is a type of energy that we cannot see, but it affects us every day. When our skin is exposed to UV rays, it starts making vitamin D, which is important for healthy bones, blood cells, and our immune system. However, if we get too much UV, it can harm the DNA in our skin cells. This damage can build up over time and increase the risk of skin cancer, including melanoma, which is one of the most dangerous types. UV exposure also makes our skin age faster, causing wrinkles and loose skin. It can even damage our eyes and lead to problems like cataracts.

To help people understand how strong the sun's rays are, scientists use the UV Index. The UV Index is a scale that starts at zero and can go above ten. The higher the number, the stronger the UV radiation and the greater the risk of harm to your skin and eyes. The UV Index is usually highest around midday, when the sun is at its highest point in the sky. In the UK, the UV Index is typically around five or six during the summer, but in places closer to the equator, it can be above ten all year round.

The World Health Organization gives advice based on the UV Index. When the UV Index is low, between one and two, you do not need to worry much about sun protection. When it is medium, between three and five, or high, between six and seven, you should use sunscreen and take other steps to protect yourself. When the UV Index is very high, between eight and ten, or extremely high, eleven or more, you need to be extra careful.

Protecting yourself from UV radiation is important for everyone, no matter your age or skin color. The best way to protect your skin is to use sunscreen with an SPF of 30 or higher and at least four-star UVA protection. Apply sunscreen to all exposed skin, including your face, neck, ears, and head if you have thin or no hair. Put it on about 30 minutes before you go outside, and reapply every two hours, or more often if you sweat, swim, or dry off with a towel. Adults should use about six to eight teaspoons of sunscreen to cover their whole body.

Besides sunscreen, you should wear protective clothing, sunglasses, and a hat. Try to stay in the shade when the sun is strongest, usually between 11 am and 3 pm from March to October in the UK. Children are more sensitive to UV, so they need extra protection, even at lower UV levels.

Some people think getting a tan is healthy, but doctors say there is no safe way to tan from the sun. Tanning is your skin's way of trying to protect itself, but it does not give much protection. If you want to look tanned, it is safer to use self-tan products.

You can still get sunburned on cloudy or windy days because UV rays can go through clouds. The temperature does not affect how much UV reaches your skin, so you can burn just as easily when it is cool as when it is hot.

Even people with darker skin need to be careful. While darker skin has more natural protection, it is still possible to get skin cancer and other problems from too much UV. Everyone should take steps to protect themselves from the sun, especially during heatwaves or when the UV Index is high.