The document discusses the discomfort index theory, which aims to quantify the combined impact of temperature and humidity on human discomfort. The discomfort index is calculated using a formula that takes into account the temperature in Celsius and relative humidity. This index number can then be used to interpret different levels of population discomfort, ranging from no discomfort to a state of medical emergency. An example calculation for Mumbai shows a discomfort index of 29.01, indicating that everyone would feel stressed according to the theory.