The corona pandemic COVID-19 virus that attacked has made some Indonesian people like sunbathing. Sunbathing is believed to increase body immunity to prevent COVID-19 infection.

But it seems that sunbathing cannot be done haphazardly. Someone must know the right time to sunbathe so that exposure to UV ultraviolet rays does not damage human skin.

Summarizing from the official page of the Meteorology and Geophysics Agency, in general the band of light waves is divided into three parts. The first is UV light with a wavelength of 100-400 nm.

Second is the light that can be seen by the human eye at 400-700 nm. While the third is infrared (IR) with a wavelength of 700 nm to 1 mm. IR rays have characteristics similar to UV that is cannot be captured by the eye.

UV rays are part of the electromagnetic waves of solar radiation energy that reaches the earth’s surface. World Meteorological Agency (WMO), said that less sunlight will affect one’s mood and cause vitamin D deficiency.

But if you receive excessive sun exposure it will pose a danger to human health. Therefore, people are advised not to be careless when sunbathing.

UV rays in the 100-400 nm wave are divided into three categories. Namely UV A, namely 316-400 nm, UV B with 280-325 nm and UV C 100-280 nm. When entering the atmosphere almost all UV C will be retained in the ozone layer.

While 90 percent of UV B will be absorbed by ozone, water vapor and other gases in the atmosphere. Whereas UV A can mostly reach the surface of the earth. Thus, the total sunlight reaching the earth is UV A (90-99%) with a little UV B (<10%).

The UV index explains the level of exposure to UV radiation which will be related to human health. This UV index can help humans to monitor the level of UV rays that are good for the body and which are harmful to humans.

UV Index is divided into 11 levels which can be seen from the change in color. The United Stated Environmental Protection Agency (EPA) explains the five UV Index indicators.

UV Index 1-2 (Low), marked in Green: No protection required. A person can stay safe outside the home and get minimal sunlight.

UV Index 3-5 (Moderate), marked in Yellow: Protection is required. Look for shade in the morning to evening.

UV Index 6-7 (High), marked in Orange: When outside, you should apply sunscreen on exposed skin. Also wear protective clothing, wide-brimmed hats, and sunglasses.

UV Index 8-10 (Very High), marked in Red: extra protection is needed. Be careful if you are outside the home.

UV Index 11 and above (Extreme), marked in Purple: If the shadow is shorter than you, then look for a shady place and wear protective clothing such as a wide hat, and sunglasses. Also apply sunscreen on exposed skin.

UV Index today can be seen through the table below:

https://www.epa.gov/sunsafety/uv-index-scale-0

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