Ultraviolet (UV) radiation index
Before doing outdoor activities, check the UV index for your area: it tells you how much protection you need and at what times it is best to avoid the sun.
What each level means
The World Health Organization recommends adapting outdoor activity and using protection when the index is 3 or higher. The highest index of the day occurs in the hours around solar noon.
| UV index | Level | What to do |
|---|---|---|
| 0 to 2 | Low | Minimal risk; under normal conditions no special protection is needed. |
| 3 to 5 | Moderate | Protection: shade around midday, clothing, a hat, sunglasses and sunscreen. |
| 6 to 7 | High | Protection needed: reduce midday sun exposure. |
| 8 to 10 | Very high | Extra protection: avoid being outdoors around midday. |
| 11 or more | Extreme | Avoid the midday sun; take all protective measures. |
Tips for outdoor activities
- Schedule your activity early in the morning or late in the afternoon, outside the hours when the index is 3 or higher.
- A practical rule: if your shadow is shorter than you are, the radiation is intense.
- Shade, clothing and a hat are the best protection; sunscreen is applied to any skin left exposed and reapplied.
- Take special care to protect babies and children.
- Radiation increases at higher altitudes and is reflected by snow, water and sand.
The sun also has a necessary side: your skin produces vitamin D with sunlight. See the article Osteoporosis.
Sources: World Health Organization, Global Solar UV Index: A Practical Guide (2002) and frequently asked questions about the UV index; U.S. Environmental Protection Agency, UV index scale. Weather data: Open-Meteo.com (CC BY 4.0).