It's a great feeling to get outdoors and enjoy the bright sunshine once in a while. But knowing when to cover up to protect against damaging UV rays is important. Understanding the UV Index can help you make informed decisions about sun protection and make your time in the sun more enjoyable.
What you need to know
Effective spring 2004 the UV Index was changed in an effort to make it more accurate and easier to understand and to standardize UV Index programs around the world. The new UV Index includes the following features:
Addition of a "Very High" category
In the past, UV Index levels were categorized as Low, Moderate, High or Extreme.
New range of UV Index numbers within each category
Low (0-2)
Moderate (3-5)
High (6-7)
Very High (8-10)
Extreme (11+)
Use of whole numbers instead of decimals
UV Index forecasts are now rounded off to the nearest whole number. The higher the number, the stronger the UV rays, and the greater the need to protect yourself.
Consideration of elevation and reflection by snow
UV Index forecasts now take into account elevation and reflection by snow since these two factors can enhance UV levels.
In terms of elevation, the higher the elevation the stronger the UV rays because the air is clearer and thinner. Expect a higher UV level the higher the elevation you go.
In terms of reflection by snow, the brighter the surface you are on, the more UV it reflects back onto your skin. Snow is highly reflective (50-80%). Expect a higher UV level on sunny days with snow on the ground.
Updated sun protection actions
Canadian health organizations such as Health Canada, the Canadian Cancer Society, the Canadian Dermatology Association and the Canadian Association of Optometrists, worked together to update the sun protection actions associated with each category of the UV Index to better help protect people from sun damage.