By Amy-Lynn Albertson

N.C. Cooperative Extension

Wet-bulb temperature measures air temperature using a thermometer covered with a water-soaked cloth exposed to air. Considering the current weather and air pressure, this method helps calculate how much water vapor the atmosphere can hold. Evaporation creates a cooling effect; dry air causes water to evaporate faster. However, if the relative humidity reaches 100 percent, evaporation ceases. For humans in hot conditions, evaporation is crucial for cooling through sweat.

Wet-bulb temperature combines heat and humidity, with temperatures above 90 marking the limit for outdoor activities. Prolonged exposure to wet-bulb temperatures above this threshold can be lethal, even with shade and water. Climate change has pushed some regions, like the Persian Gulf and Pakistan, to exceed 95 wet-bulb temperatures, underscoring the importance of considering temperature and humidity in climate projections, such as those used in ClimateCheck heat ratings.

Rowan County recently experienced black category 5 conditions, indicated by wet-bulb temperatures over 90 degrees. Under these conditions, it’s vital to limit work and rest intervals and to hydrate, aiming for at least one quart of water per hour. Protecting yourself from heat and sun is essential while gardening, just like at the beach. Seek shade whenever possible, strategizing garden activities to follow shaded areas. Avoid sun exposure between 10 a.m. and 2 p.m. when it’s strongest.

A wide-brimmed hat, at least three inches wide, is crucial for sun protection. I found a great one made by Sunday Afternoons that offers extensive neck coverage. Proper clothing is equally important; a loose, long-sleeved shirt made of breathable material and lightweight pants can greatly assist in staying cool. Shirts with a 50 UPF rating indicate sun protection, blocking up to 98 percent of harmful UVA and UVB rays.

At the Extension Center, we discovered reusable sleeves that can be worn with short-sleeved shirts. These sleeves also carry a 50 UPF rating for sun protection while featuring a cooling effect to combat heat exposure. They come in various colors, with white retaining less heat than darker tones.

Be mindful of UV exposure to the delicate skin around your eyes. Invest in sunglasses that block 99 percent of UV rays and at least 75 percent of brightness. Safety sunglasses can provide dual protection against UV light and potential impacts from garden debris.

Experts recommend a combination of physical barriers and sunscreen for the best sun protection. Mineral sunscreens, containing titanium dioxide and zinc oxide, reflect UV rays, while chemical sunscreens absorb and convert them into heat. Choose a sunscreen with a minimum SPF of 30 and reapply as directed, especially after sweating or swimming.

To check the wet-bulb temperature, visit the Piedmont Research Station’s weather station online at https://econet.climate.ncsu.edu/wbgt/.

Heat-related illnesses can progress rapidly. Be aware of the symptoms, and take action if you or someone else experiences them. If you feel overheated while gardening, try soaking a bandana in cool water and wrapping it around your neck, as this area is sensitive to temperature changes. Placing a cool, wet rag on your wrists can provide immediate relief.

Staying informed and taking these precautions can help keep you safe and healthy during hot weather. Stay calm, hydrated and protect yourself from the sun!

Amy-Lynn Albertson is director of the Rowan County Extension.