Note that there are two common "wet bulb" temperatures used in discussion:

• Wet Bulb Globe Temperature - this tells you that physical activity (including work) in unshaded locations can kill healthy adults and is used in this article
• Wet Bulb Temperature - this tells you whether it is hot enough to kill the bulk of the population for just sitting still in the shade with access to plenty of water

A Washington Post analysis found that the wet-bulb globe temperature, which measures the amount of heat stress on the human body, reached 97 degrees to 100 degrees (36 to 38 Celsius) in Delhi on Tuesday. That is higher than the 89.6 Fahrenheit (32 Celsius) threshold that researchers have identified as posing a risk to human survival if such heat is prolonged. The wet-bulb globe temperature is based on a combination of factors including temperature, humidity, wind and clouds, and was calculated by The Post using data from a nearby weather station.