How to judge the intensity of UV rays?

The level of ultraviolet radiation is affected by many factors, such as the height of the sun, latitude, cloud cover, altitude, and ground vegetation conditions. Generally speaking, the higher the sun angle, the higher the altitude, the clearer the weather, and the better the transparency of the atmosphere, the stronger the UV intensity.

What are UVA, UVB, UVC?

UVA：

• 90% of ultraviolet rays are UVA, which has strong penetrating ability and is the main reason for skin aging. It not only tans the skin, but also causes photoaging and even skin cancer. UVA is not blocked by windows, umbrellas, cloudy rain, etc., so remember to apply sunscreen on cloudy and rainy days!

UVB：

• It is not easy to penetrate the glass and can only reach the epidermis of the skin. It can cause skin sunburn, causing peeling, erythema, tanning, etc., but it can be blocked by umbrellas and clothes.

UVC：

• It cannot reach the ground and is absorbed in the ozone layer.

In general, both UVA and UVB are the main culprits that cause skin tanning and aging. The difference is that UVA can reach the dermis layer of the skin, while UVB can only reach the epidermis layer of the skin, and UVB is not evil, it can promote the synthesis of vitamin D, Vitamin D promotes the absorption and conversion of calcium.