1. Low (0-2):

- Description: Minimal risk of harm from UV radiation.

- Recommendations: Sunscreen is generally not needed, but wearing sunglasses can still be beneficial to protect the eyes.

- Typical Locations/Times: Early morning or late afternoon, during winter in temperate regions, or in high-latitude locations like Northern Europe or Canada during winter.

2. Moderate (3-5):

- Description: Low to moderate risk of UV damage for most people.

- Recommendations: Take basic precautions like wearing sunglasses, sunscreen (SPF 15 or higher), and staying in the shade during midday.

- Typical Locations/Times: Mid-morning to early afternoon in temperate regions during spring or autumn.

3. High (6-7):

- Description: Increased risk of harm from unprotected sun exposure.

- Recommendations: Cover up with clothing, use sunscreen (SPF 30+), wear a wide-brimmed hat, and seek shade, especially during midday hours.

- Typical Locations/Times: During summer in temperate regions (e.g., Southern Europe, parts of the U.S.), or in tropical areas during cooler seasons.

4. Very High (8-10):

- Description: High risk of skin and eye damage from UV rays.

- Recommendations: Extra protection is required. Use broad-spectrum sunscreen (SPF 30+), wear protective clothing, sunglasses, and a hat, and avoid the sun during midday (10 a.m. to 4 p.m.).

- Typical Locations/Times: Summer in tropical regions or at higher altitudes, deserts, and southern temperate zones (e.g., Australia, parts of Africa, Central America).

5. Extreme (11+):

- Description: Very high risk of UV-related harm, with unprotected skin and eyes potentially damaged in minutes.

- Recommendations: Full sun protection is essential. Avoid being outdoors during midday, use sunscreen (SPF 50+), and wear sunglasses, hats, and clothing that covers exposed skin.

- Typical Locations/Times: Areas close to the equator, high-altitude regions, deserts, and during summer in countries like Australia, parts of South America, and Africa.

Factors Influencing UV Levels:

1. Latitude: The closer to the equator, the higher the UV Index, since the sun’s rays are more direct.

2. Altitude: Higher altitudes experience stronger UV radiation, as there is less atmosphere to filter UV rays.

3. Time of Day: UV radiation is strongest between 10 a.m. and 4 p.m. when the sun is highest in the sky.

4. Season: UV levels are higher in the summer months when the sun is more directly overhead.

5. Weather Conditions: Clear skies lead to higher UV levels, while clouds can reduce UV radiation. However, even on cloudy days, up to 80% of UV rays can still penetrate.

6. Reflection: Surfaces like snow, sand, water, and pavement can reflect UV radiation, increasing exposure.

UV rays are a major cause of skin cancer, sunburn, and premature skin aging. By knowing the UV Index and taking precautions accordingly, people can reduce their risk of skin damage and protect their health effectively.