Hot enough for you? Here’s how to tell

The average human body temperature ranges from 36.5-37.2 degrees Celsius, with variations depending on factors at that moment, as well as the quality of the measuring equipment or the accuracy and suitability of the measurement method.

The average human body temperature varies across different age groups, influenced by various external factors as well. Here are the typical body temperature ranges:

Infants: Average body temperature ranges from 36.6-37.2 degrees Celsius.

Adults: Average body temperature ranges from 36.1-37.2 degrees.

Elderly aged 65 and above: Average body temperature tends to be lower than 36.2.

If the body temperature exceeds 37.2 degrees Celsius (99.5 degrees Fahrenheit), it may be considered abnormal and could serve as a warning sign of various conditions such as headache, fever, or other symptoms.

Under normal circumstances, the human body temperature should be higher than the ambient temperature so that heat can be effectively dissipated from the body. Our skin typically maintains a constant temperature of around 35 degrees Celsius. However, if humans are exposed to temperatures higher than 35 degrees with relative humidity exceeding 75% continuously for more than six hours, our bodies may start experiencing excessive heat or hyperthermia. This is because prolonged exposure to external heat pushes the body temperature higher than the normal range of 36.0-37.0 degrees, leading to heat-related complications.

In this condition, we would become aware that our body is experiencing abnormalities. We might feel internal heat spreading, a high fever, and if the temperature reaches 40 degrees Celsius, the body enters a state of heat stress. The body would appear red and excessively hot internally. At this stage, the nervous system and internal organs begin to deteriorate. This is a dangerous point that can lead to heat stroke, potentially resulting in death due to organ failure, blood and oxygen deprivation, and the heart overworking to supply blood to various parts of the body, leading to heart and organ failure.

When we hear weather forecasts reporting that the temperature will reach 40 degrees Celsius, it doesn't mean that our body temperature will rise to 40 degrees as well. This is because, naturally, when the temperature inside our body rises, we have a mechanism called sweating or perspiring to release heat from the body. This mechanism helps prevent our body from overheating. However, at the same time, sweating causes significant water loss from the body. Therefore, it's advisable to drink plenty of water on hot days to replace the lost fluids.

Therefore, the answer to the question of how much heat the human body can tolerate depends on various factors, one of which is the concept of "wet-bulb temperature", the lowest temperature to which air can be cooled by the evaporation of water into the air at a constant pressure. This is because our bodies can only tolerate heat up to a wet-bulb temperature of no more than 35 degrees Celsius.

In short, to determine how much heat the body can endure, we need to consider the moisture content as well.

Wet-bulb temperature is not the general temperature measured by a regular thermometer, but rather the temperature calculated when considering the humidity in the air as well.

The more moisture (humidity) there is in the air, the harder it is for sweat to evaporate from the body, making heat dissipation more difficult. When both humidity and temperature are high, the wet-bulb temperature can rise to dangerous levels.

For example, when the air temperature is 46 degrees Celsius and the humidity is 30%, the wet-bulb temperature will be approximately 30.5 degrees Celsius. This temperature, although hot, is still tolerable for the human body. On the other hand, when the air temperature is 39 degrees Celsius but the humidity is high at 77%, the wet-bulb temperature will be 35 degrees Celsius, which is already dangerous.

The reason why higher humidity in the air makes us feel hotter than the actual temperature is linked to "relative humidity," which plays a crucial role in how effectively our bodies can dissipate heat through sweat. When we are in a hot environment but the relative humidity is low, around 40-45%, our bodies can effectively sweat and evaporate the sweat, which helps us feel cooler, especially when there is a breeze.

However, if the relative humidity in the air is high, reaching 80-90% or more, this dense moisture makes it difficult for our bodies to efficiently evaporate sweat. Instead of evaporating, the sweat may simply bead up and make us feel sticky and uncomfortable. This prevents effective cooling through sweat evaporation, and our body temperature doesn't decrease. Additionally, we lose more water from our bodies in such conditions.

In summary, The human body can tolerate internal heat up to a maximum of around 42 degrees Celsius and external heat from the surrounding environment up to 50-60 degrees Celsius. However, if the body temperature rises above 40 degrees Celsius, it can lead to severe and life-threatening heatstroke symptoms.