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Temperatures are rising quickly across the U.S., prompting construction crews to begin monitoring the weather, their water intake, and heat stress symptoms. By integrating weather insights into construction safety management, teams can make more informed and safe-heat or storm-related decisions based on real-time information.

Brad Nelson, a solution engineer and on-site event meteorologist at DTN, works closely with the data, analytics, and technology company’s risk communicator team to forecast weather and risk impacts for business continuity, safety, and logistics. Nelson says, “Access to weather analytics is one of the most underused, yet readily available, resources businesses can use today to prepare for the future.”

Brad Nelson
DTN Brad Nelson

To learn more about the risks related to extreme heat and how builders can monitor safety, BUILDER asked Nelson for further advice beyond just watching the temperature on your favorite weather app.

BUILDER: What are some ways builders can protect workers from heat-related stress?

Nelson: Getting field workers ready for extreme heat involves planning, training, and education on how to prepare and what to do in the event of extreme temperatures. With extreme heat, it’s essential to know how to identify dangerous conditions with the Wet Bulb Globe Temperature (WBGT), to have a heat stress prevention and mitigation plan, and to implement the training and tools to help people susceptible to heat stress if it does happen. The medical community and research, like from the National Institutes of Health, state that exertional heat stroke has a 100% survival rate when quickly recognized and treated. When used in conjunction with a comprehensive response plan for extreme temperatures, the WBGT information can mean the difference between life and death.

As part of that plan, it’s important to know the local weather safety standards. There is no federal heat stress standard, but several states, including California, Washington, and Minnesota, have passed state-level heat standards, which should be part of operation manuals and manager training. The Centers for Disease Control and Prevention includes recommendations for employers about how to prevent heat-related illnesses, including using an acclimatization protocol, establishing a heat alert program, and providing heat stress training.

BUILDER: What is Wet Bulb Globe Temperature?

Nelson: WBGT was developed in 1956 by the U.S. military to help reduce heat stress in recruits. The WBGT measures heat stress in direct sunlight, which makes it different from the heat index, which also looks at temperature and humidity but in shady areas. WBGT also considers wind speed, cloud cover, and sun angle. While not as commonly referenced as the heat index, WBGT is a vital index and more accurate for addressing how prolonged exposure to heat pushes the human body beyond its limits. When extreme heat combines with high humidity, it can become a potentially lethal situation.

BUILDER: How can WBGT be monitored?

Nelson: Tools for measuring WBGT are quite specific, and most free forecasts do not include WBGT predictions. There are several WBGT monitoring devices on the market that can be used to assess current WBGT indices accurately. But to monitor the future conditions for WBGT, you need to have access to a WBGT forecast, such as through DTN WeatherSentry, and follow the specific guidelines, which include recommended times, duration, and breaks for activity.

BUILDER: Is it more effective to track WBGT in certain climates of the U.S.—humid versus dry areas?

Nelson: WBGT is effective in every type of climate, whether that be in humid or dry areas. Since WBGT takes relative humidity into the equation, the index will adjust based on humid, temperate, or dry climates and is consistent across all geographies.

BUILDER: How does WBGT differ from the heat index?

Nelson: The heat index measures how hot it feels when relative humidity is factored with the actual air temperature and in the shade. It is important to note that WBGT and heat index/temperature values cannot be compared directly since WBGT is a stand-alone index for heat stress.

BUILDER: What ranges are considered dangerous when referring to WBGT?

Nelson: While there isn’t a federal standard establishing WBGT danger levels, OSHA does note that at the simplest level an effective WBGT greater than 77 degrees Fahrenheit is when heat stress could become a problem for all acclimatized outdoor workers. As the WBGT rises, the risks increase, and there are many resources offering ranges to consider, identifying temperatures from “low threat” to “extreme threat.” But many factors must be considered when consulting those danger levels for your workforce. Some factors to consider include whether or not the workers are acclimatized, what kind of PPE they wear, and their general health and fitness.

There are many resources with detailed, established risk levels for safety teams to consult as they establish the right threshold for their teams. Many states have their own OSHA-approved plans as mentioned above, the Department of Health and Human Services offers guidance, and there are other great resources like industry associations and the Korey Stringer Institute that provide comprehensive insights for planning and establishing thresholds.

Identifying that threshold for effective WBGT is the most essential part of the planning process when considering heat safety. The NAHB offers a heat safety toolkit with ideas that include acclimatizing workers to the heat, modifying work schedules with more rest breaks, encouraging hydration, offering protective clothing that provides cooling, and, above all, monitoring for symptoms of heat stress.

BUILDER: Are there any common misconceptions related to heat safety?

Nelson: While my expertise is in measuring the WBGT and providing guidance on forecasts and overall weather impacts, many experts, including those at the Korey Stringer Institute, say the biggest misconception about heat safety is that hydration is the only thing that prevents heat stress or heat stroke. Yes, hydration matters, but workers can still suffer heat stress or stroke while hydrated. Implementing cooling strategies, such as cold towels, and ensuring an appropriate work-to-rest ratio based on the WBGT are a few other essential considerations, along with staying hydrated.

BUILDER: What’s your go-to heat safety advice as the high temps of summer arrive?

Nelson: I feel like a Boy Scout when I say this, but my go-to advice is to tell people to 'be prepared and have a plan.' Weather insights inform emergency responses, so an entire team must have access to real-time, accurate WGBT information. Knowing when and where extreme heat is happening on a hyperlocal level can help ensure that outdoor workers have the right plans and responses.

Having accurate temperature information and forecasts during extreme temperature events ensures that field workers are prepared to respond to the temperatures, with resources in place to make sure all workers stay safe. Ideally, a general contractor or construction firm will have counsel and input from meteorologists to help understand the severity and timing of extreme temperature events. If you have teams in multiple regions, or across the country, it would be beneficial to consider using risk communicator services. A risk communicator is a meteorologist with industry expertise and can advise on heat, and other weather risks, tailored to the specific conditions at the worksite.