Point to the Index: The UV Index
The National Weather Service (NWS) and the Environmental Protection Agency (EPA) developed the Ultraviolet (UV) Index in 1994. The UV Index is a useful tool to help the public take steps towards reducing UV radiation exposure, since skin cancer and other skin diseases have increased significantly in the US since 1975.
The UV Index tells us the level of UV exposure expected on a given day. The categories are: low, moderate, high, very high, and extreme with corresponding index numbers 1-2, 3-5, 6-7, 8-10, 11+. The UV Index reminds people to protect themselves when engaging in outdoor activities.
The EPA encourages consumers to practice the following sun protection steps:
- Check the UV Index for the UV forecast.
- Limit exposure during midday hours.
- Seek shade.
- Wear clothing made from tightly woven fabrics. UV rays can pass through holes and spaces in loosely knit fabric. Long-sleeved shirts and pants are recommended.
- Wear a hat with a wide brim that protects the eyes, face, and neck.
- Wear sunglasses that provide 100% UV protection.
- Use broad spectrum sunscreens with at least Sun Protection Factor (SPF) 15 and reapply regularly. Remember to apply sunscreen on any part of the skin that is exposed to the sun, such as the nose, the back of the neck, and the rims of the ears. Use lip balms or creams containing sunscreen.
Here’s the chart straight from the EPA:
So, you might be wondering how is the Index calculated?
In a nutshell, it begins with forecasting the total ozone amount by using NWS models. Then, the sun angle for that specific day is determined. Next, a radiation model determines different UV radiation wavelengths, which are then weighed into human skin. Lastly, outside factors such as location, sea level and cloud conditions are measured and adjusted to the index.
The UV Index is a great tool to educate yourself on how intense each day’s sun exposure will be. The sun can be extremely harmful, as most of us know, causing anything from wrinkles, to eye damage, to skin cancer. It’s great to have this kind of knowledge in order to prevent these things from happening to you.