Wet Bulb Globe Temperature
- Wet Bulb Globe Temperature (WBGT)
- Wet Bulb Globe Temperature: measure of the heat stress in direct sunlight, which takes into account: temperature, humidity, wind speed, sun angle and cloud cover
- Used by employers, athletes, sporting events and military to determine appropriate exposure levels to high temperatures
- Can reliably predict environmental heat stress
ACSM 5 Colored Flags
- Black flag level: WBGT greater than 82°F (28°C),
- races should be cancelled or recommends voluntary withdrawal
- Races that are always held in these conditions should acknowledge the extreme heat risk to the poorly acclimated and non-resident competitors
- Announcement should be in the pre-race literature and the pre-race announcements
- Red flag level: WBGT is between 73°F to 82°F (23°C to 28°C).
- Participants who are at increased risk for heat collapse are recommended to withdraw from the race
- It is recommended that all other participants slow their pace to match the conditions
- Yellow flag level: WBGT between 65°F to 72°F (18°C to 22°C).
- ACSM recommends that participants at increased risk for heat collapse slow their pace
- Entrants should be warned of increased risk of heat collapse
- Green flag level: WBGT less than 65°F (18°C).
- Although collapse can still occur, there is a decreased risk of hyperthermic and hypothermic collapse
- This is an ideal level for a marathon
- White flag level: WBGT less than 50°F (10°C).
- There is increased risk of hypothermic collapse
- participants should be advised to wear appropriate clothing