Heat stress occurs when the body cannot cool itself fast enough.
Unlike air temperature alone, our index accounts for three real-world factors:
ambient heat, humidity blocking sweat evaporation, and direct solar radiation
heating the skin.
💧
Humidity is the silent danger — at 80% RH, sweat barely
evaporates and the body's cooling system shuts down.
☀️
Solar radiation heats exposed skin directly.
A child in direct sun experiences an additional 4–8°C of thermal load
beyond air temperature.
👶
Children overheat faster — their body surface-to-mass
ratio is higher, sweat glands less developed, and they rarely self-limit
activity. The safe threshold for children is 3–4°C lower
than for adults.
Calculated using WBGT (Wet Bulb Globe Temperature) —
the international standard used by WHO, military medicine, and sports science.
WBGT = 0.7 × Twet + 0.2 × Tglobe + 0.1 × Tdry
Validated against NOAA real-sensor measurements: mean error <0.65°C.