Graphic illustration by Emily Funderburke Flag conditions are based on the Wet Bulb Globe Temperature Index which is a calculation of temperature, humidity, wind speed and solar radiation levels.

In hot conditions, Marines need to payattention to the heat index flags to make sure they are working and training in a safeenvironment, said Cpl. Luke Peterson, a weather forecaster.

The flags are in effect from May 1 – Oct. 31. During this time, heat conditions are measured outside by censors located at the Marine Corps Air Facility. They are then categorized into four conditions using the Wet Bulb Globe Temperature Index, a devise that calculatesthe outside air temperature, humidity, radiant heat and air movement.

Once the data is collected, theweather analysis Marines indicate theappropriate color flag based on the possibility of heat-related injures or casualties.

The purpose of the flags is to warn people on base that the temperature and humidity have reached a dangerous level, Peterson said. ‘‘The command wants to make sure Marines are working and training in a safe environment, so they can be most effective. For example, if Marines are working on a hot day on the flight line, we want tonotify their command of the heat conditions so they know to bring Marines in during the hottest hours or give them extra water.”

According to the WBGTI, a green flag, the lowest level, advises supervised heavy exercise be allowed when the index is between 80-84.9 degrees. A yellow flag, 85-87.9 degrees, allows for strenuous exercise, however outdoor activities should be avoided. A red flag is flown oncethe WBGTI has reach 88-88.9 degrees and physical training is not authorized for Marines who havenot acclimatized.

When the index reaches 90 degrees and above, a black flag is raised. It is advised that all unit PT be suspended. Per Marine Corps Base Order 6200.1A, ‘‘Essential outdoor physical activity will be conducted at a level that is commensurate with personnel acclimatization as determined by the unit’scommanding officer in the coordination wit the unit’s medical officer or medical personnel.

‘‘All efforts should be made to reschedule these activates duringcooler periods,” according to thebase order.

Heat flags not only concern Marines, but civilians as well. Civilians should take the same precautions when serious issues arise such as a red or black flag. Civilian employees are also asked to adhere to heat flag regulations listed under the Base Master Agreement,Peterson said.

For daily information on heat flags during work hours call 703-484-5502. After hours call 703-784-5321. Information is also posted at www.quantico.usmc.mil.

Heat flags are are posted at various locations, including Lejeune Hall, Marine Corps Air Facility, Officer Candidates School, Staff Noncommissioned Officer Academy, Geiger Hall, Headquarters andService Battalion, The Basic School, Camp Upshur and Range Control.

— Correspondent: jahn.kuiper@usmc.mil