UV Index Alert ‘Extreme’ for July 23

The UV Alert is "extreme" for the Tamap Bay area July 23, and also for 20 other cities in the nation where the ultraviolet index forecast is 11 or higher — up from 17 total cities the week before.

Valid for "solar noon," the July 23 UV Index forecast for the Tampa Bay area is 12.

This is the highest forecast among the 58 readings taken and the same UV Index forecast for Albuquerque, Honolulu and Miami.

All three times Brandon Patch has posted UV Index forecasts (July 10, 16 and 23) the Tampa area has been under an “extreme” UV Alert.

The second-highest UV Index for July 23 is 11, forecast for 17 cities, up from 12 the week before.

The lowest UV Index is 3, forecast for Anchorage. Next lowest is 6, forecast for Boston and Cleveland. (See chart below.)

What Is the UV Index

The UVI is "the next-day forecast for the amount of skin-damaging radiation expected to reach the earth's surface at the time when the sun is highest in the sky," according to the National Weather Service.

The UV Index ranges from O (at night) to 16 (as in the tropics, at high elevations under clear skies).

The higher the UV Index, the greater the "dose rate" of skin- and eye-damaging ultraviolet radiation, according to the National Weather Service.

The UV Index is categorized by the World Health Organization as follows:

• LOW — 0, 1, 2
• MODERATE — 3, 4, 5
• HIGH — 6, 7 
• VERY HIGH — 8, 9, 10
• EXTREME — 11-16

Overexposure Risks

According to the National Weather Service, overexposure to ultraviolet radiation can cause the following:

• Severe sunburn, following an intense, short-term overxposure.
• Melanoma, the more deadly of the two types of skin cancer, following several intense, short-term overxosures.
• Non-melanoma skin cancers, which are almost 100 percent curable after overexposure for very long periods of time, as is experienced typically by construction workers, farmers and fishermen.
• Catracts in the eyes, also following long-term exposure.

SUN-SAFETY TIPS

The Hillsborough County Extension Office, through the University of Florida Institute of Food and Agricultural Sciences, offers the following tips for avoiding the dangers of overexposure:

Do Not Burn

• Five or more sunburns can double the chances of getting skin cancer.

Monitor UV Levels

• Limit outdoor activities between 10 a.m. and 4 p.m. when the UV Index is "high" (6 or 7), "very high" (8, 9 or 10) or "extreme" (11 or higher).

Apply Lots of Sunscreen

• Apply a broad-spectrum sunscreen (SPF of at least 15) 20 minutes before going outside. Re-apply the sunscreen again every two hours, and after swimming or sweating.

Protect Head and Eyes

• Wear wide-brimmed hats for better sun protection. Wear sunglasses with 99-100 percent UV-A and UV-B protection.

Use Extra Caution Near Water and Sand

• Water and sand (and snow) reflect UV rays, causing extra exposure.

Avoid Tank Tops

• Wear T-shirts or long-sleeved shirts as opposed to lessen exposure of shoulders and sides.