What is the UV Index?

The UV index is becoming the next hot topic at pool parties this summer. While some think a higher number is more efficient for tanning, it actually means it’s more dangerous during long exposure times.

Understanding UV

The UV Index is a forecasted value of the Sun’s ultraviolet radiation expected for a day. The forecasted number is the maximum value expected in the middle of the day when the Sun is at its peak. In reality, the UV Index varies through the day.

UV indices

The Environmental Protection Agency (EPA) has broken down UV exposure categories into a scale of 1 through 11 or higher.

When the UV Index is High, Very High, or Extreme, sunburn prevention is necessary. Additionally, the EPA recommends individuals avoid time outside between 11 AM and 4 PM when the UV index is a 6 or higher.

Furthermore, a UV Index ranging from 1 to 5 can still pose a health risk when proper protections are not taken.

Why Limiting UV Exposure Matters

When you tan, the change in your skin color is actually your body’s defense mechanism to prevent further harm from UV radiation. Recurring exposure to UV radiation will cause genetic mutations in skin cells that can lead to skin cancer.

Additional health issues from UV exposure include premature skin wrinkles and a weakened immune system.

What Else Determines the UV Index

Variations in the UV Index can be attributed to multiple factors in your location.

Seasons – UV radiation is higher in the spring and summer because the Northern Hemisphere is tilted toward the Sun, making sunlight more concentrated.
Latitude – UV radiation is strongest at the equator.
Altitude – As altitude increases, air becomes thinner by having less molecules which means UV radiation is less likely to be scattered or absorbed.
Cloud Cover – Thin clouds allow UV to pass through, while puffy and thick clouds deflect UV.
Ozone – Ozone is a gas that absorbs UV radiation. Ozone concentrations vary between days and locations.
Surface characteristics – Trees, water, snow, sand, and concrete can reflect UV and in some cases further your exposure.

Facts About UV Exposure

You can get sunburned on a cloudy day.
Sunscreen is supposed to help protect you from UV exposure, not allow you to extend time in the Sun.
Taking a tanning break will not prevent you from becoming sunburned. UV exposure is cumulative.
Research has shown skin cancer to be a common occurrence for those who tan before burning.

You can find more information about the UV Index here.