The ROCK gets HOT

  • Published
  • By Airman 1st Class Heather Luke
  • 19th Aerospace Medicine Squadron Bioenvironmental Engineering Flight
LITTLE ROCK AIR FORCE BASE, Ark --  Have you ever wondered what it means when you get the computer-generated, mission-essential statement of the heat index and why it's important? Well here is some "Did you know...?" to help you understand why!

Arkansas is No. 6 in the top hottest states during the summer. In 2012, Arkansas had a high of 110 degree at the end of July. Currently, Aug. 3, 2011, holds the record for the hottest day since July 1936 at 114 degrees.

There are five heat categories that coincide with the Wet Bulb-Globe Temperature index with corresponding flag colors:

Category WBGT Index (degrees) Flag Color
1 78 - 81.9 No Flag
2 82 - 84.9 Green
3 85 - 87.9 Yellow
4 88 - 89.9 Red
5 90 and above Black

The WGBT reading is a mathematical ratio of three distinct readings: the air temperature, radiant heat and the relative humidity. It was originally used as a simple measurement of heat stress by military organizations during training in high thermal conditions; however, it became so effective in monitoring heat stress that it was widely adopted throughout the Department of Defense.

Here at the Rock, the WBGT index is determined at 2-hour intervals between 8 a.m. and 4 p.m. during the normal duty day, when the actual or forecast temperature reaches 85° F. When the WBGT index reaches Heat Category 3, the Bioenvironmental Engineering Flight monitors the WBGT every hour. Once the WBGT reaches Heat Category 1 or higher, the BEF reports the category to the 19th Airlift Wing Command Post. When the Command Post is notified that the WBGT reaches Heat Category 3, the giant voice (loudspeaker system) and computer installation warning system (AdHOC) are activated.

All individuals are subject to heat stress injuries, so prevention is critical. Throughout the day, people lose fluids by sweating and water loss is amplified during physical work/physical training, which could lead to dehydration. Work and mandatory PT schedules should be tailored to fit the climate, physical condition of personnel and the military situation. For example, heavy work should be scheduled for the cooler hours of the day, avoiding the heat of early afternoon whenever possible. Commanders and supervisors must stay vigilant of heat stress preventive measures during the summer months, especially when the WBGT index reaches 90 degrees (Heat Category 5). It's imperative to know and understand the work rest cycles that coincide with the heat index. Frontline supervisors should brief heat stress prevention to all personnel on a routine basis and prior to PT.

Further information on the control and prevention of heat stress can be found in Little Rock Air Force Base Instruction 48-151, which provides an all-inclusive heat stress program. When a heat notification is announced, as a result of a high WGBT index, it is important to take the appropriate precautions: avoid heavy outdoor work/PT during the hottest part of the afternoon and stay hydrated.