Is a wet-bulb temperature of 35 degrees Celsius the correct threshold for human survivability?

Abstract A wet-bulb temperature of 35 ○ C is widely used as the threshold for human survivability, but not a particularly accurate metric heat stress. For person in shade, more index, which based on model thermoregulation that accounts metabolic heat, radiation, respiratory ventilation, and finite wind speeds. The index has two critical values: highest healthy core can be maintained survivable. It shown here corresponds to conditions between these values. example, world warmer than pre-industrial by 10 C, about 30% world's population would exposed once or per year above reveals less 2% fatal while over 60% cause hyperthermia.