At what WBGT temperature is no flag indicated, suggesting extreme exertion may lead to heat illness?

The correct answer indicates that at temperatures below 78 degrees Fahrenheit, there is generally no flag warning, suggesting that while extreme exertion might lead to heat illness, it is less likely compared to higher temperatures. The Wet Bulb Globe Temperature (WBGT) index is utilized to assess the heat stress in direct sunlight. Below 78 degrees is often considered a safe range for most physical activity, as the risk of heat-related illnesses significantly increases at higher temperatures.

At threshold temperatures above this level, such as those falling within the 78-82 degree range, and particularly beyond 82.1 degrees, precautions and warning flags become more pertinent as the risk for heat exhaustion and heatstroke increases. Thus, below 78 degrees is viewed as a safer zone where, while exertion should still be monitored, the likelihood of heat-related incidents is diminished in athletic settings.