6/7/2012 - JOINT BASE SAN ANTONIO-RANDOLPH, Texas –
Sometime every spring, typically in May, computer users at Joint Base San Antonio-Randolph start receiving nearly daily messages that pop up on their screens and require an acknowledgement.
The messages play a major role in keeping Randolph personnel safe by displaying the wet bulb globe temperature index, a calculation of heat, humidity and other factors that lets supervisors know it's time to take steps to protect their workers from heat stress.
The WBGT, as it is more commonly known, triggers five "flag conditions" that are especially relevant to anyone at Randolph who is subjected to South Texas' often- oppressive heat and humidity, including Airmen who take part in physical training, security forces, firefighters, personnel on the flightlines and groundskeepers.
"It's situational awareness of what the temperature is," Senior Airman Jerome Salazar, 359th Aerospace-Medicine Squadron bioenvironmental engineering technician, said. "It assists commanders and supervisors in making decisions about rest and work cycles and water intake."
Flag conditions are displayed in five colors, ranging from white for a WBGT of 78 to 81.9 degrees to black for a WBGT of 90 degrees or more. Other flags are green, 82 to 84.9 degrees; yellow, 85 to 87.9 degrees; and red, 88 to 89.9 degrees.
"When the flag condition is green, we report it to the command post at JBSA-Lackland, and they distribute the message to the appropriate organizations on base and through the computer pop-up notifications," Salazar said. "The message only changes when the flag condition changes."
Personnel at the 359th AMDS use a device called a thermal environment monitor to measure the WBGT. The monitor features three temperature elements - a "wet bulb" that accounts for humidity and air movement, a black "globe" that measures radiant heat from the sun and a shielded thermometer that records ambient temperature.
A combination of temperature measurements that factor dry air temperature, air movement, relative humidity and radiant heating, the WGBT index "is the simplest and most suitable technique to measure environmental factors that most nearly correlate with deep body temperatures and other physiological responses to heat," according to Air Education and Training Command Instruction 90-801, "Prevention of Heat Distress Disorders."
Salazar said 359th AMDS technicians take the WBGT device outside to an unshaded location behind the medical clinic each day "when we know it will be hot." The season generally lasts from May to September or October.
"We look at the projected high temperature from weather forecasts and put the device outside by at least 8 a.m. if the projected high will be 85," he said. "We start monitoring it every hour when it gets to 85."
A remote display inside the 359th AMDS bioenvironmental engineering section records the outdoor WBGT, Salazar said.
Once supervisors know flag conditions, they can implement work/rest cycles and water intake based on the AETC I90-801 chart in attachment 2, which provides guidelines based on flag conditions and the level of physical activity, from easy to hard, as well as a wealth of information on preventing heat stress disorders, training requirements, and heat stress and water intoxication warning signs and symptoms.
By drinking plenty of water or other noncaffeinated, nonalcoholic beverages and following other commonsense guidelines, personnel can prevent heat-related illnesses such as cramps, exhaustion and heat stroke.