What is your best temperature?

As if temperatures had not already become a constant factor in our lives, the pandemic brought hand-held thermometers and infrared heat cameras to the entrance of every building. In one strangely funny instance, a door guard took my temperature and quickly said “step aside,” showing me the reading: 39.1 degrees Celsius. I very much doubted that I was sick and, just as I was about to protest, the guard said: “Don’t worry, we’ll redo it in a few minutes, very often it’s an erroneous reading.” And so it proved to be.

From that incident and the general anxiety the pandemic has induced in us, I imagined how people must be dreading thermometers. Moreover, I knew that the oft-cited figure of 37 C as the “normal” human temperature was far from the norm, but I refrained from writing about this, or even discussing it with friends or colleagues, lest I produce another controversy in times when we needed more calm and rational behavior. But now we can discuss this with cool heads — forgive the pun.

I have always been fascinated by the wide range of reactions people exhibit in hot or cold environments. My friends in Europe and North America would often ask me: “How can you live in a region (the Gulf) where daytime temperatures exceed 40 C for months?” I would retort: “How can you live in a region where daytime, not to mention night-time, temperatures are below zero for weeks or months?” And I have lost count of the number of times my students have complained, “Sir, it’s too hot in this classroom,” when the thermostat indicated barely 24 C (my ideal temperature, incidentally). I came to realize that the more people get used to round-the-clock air conditioning, the more they want the ambient temperature to be lower.

So, first, why do we like cool air? Because our bodies constantly produce heat, and to get rid of it and maintain a “good” temperature, we need the environment to be cool, and the larger the temperature difference the faster our bodies cool down. Humidity hinders the process because it makes the air less willing to take water vapor (sweat) from our bodies; in such situations, fans help remove humidity from around us and cooling becomes easier for our bodies.

So what temperature(s) do our bodies like to have? This is where we hear that famous figure of 37 C or, more knowledgeably, 36.5 to 37.5 C. However, one must stress that this is an average value that was obtained some 150 years ago by the German physician Carl Reinhold Wunderlich and people’s “normal” or “comfortable” body temperature can vary quite a bit.

Indeed, the human body’s temperature varies with several factors: Gender, age, time of day, eating and drinking (what foods have been consumed and when), sleeping, clothing, physical and/or mental activity, emotions, etc. For example, a person’s temperature is lowest about two hours before they wake up and highest in late afternoon, assuming no nap was taken. It also depends on one’s health status, such as illness and menstruation.

Last but not least, temperatures measured inside the body (in the mouth, in the ear, etc.) will differ somewhat from measurements made with hand-held thermometers aimed at someone’s forehead or arm. And not all thermometers are equally accurate.

To complicate matters a bit more, studies published just last year by researchers at the Stanford University School of Medicine found that the average human temperature has decreased by about 0.6 C since that famous 37 C figure was introduced and widely adopted more than a century ago. Similarly, a recent study in the UK found that the average temperature of 25,000 patients was 36.6 C. Please keep in mind that these are average values and that there is a range of “normal” values for different people and different circumstances. Researchers have suggested that the recent decrease in our body temperatures is the result of changes in both our general health, hygiene and lifestyle and our environment over the past century or two.

There is no golden temperature, whether for our bodies or our living and working environments.

Nidhal Guessoum

The upshot of all this is that there is no golden temperature, whether for our bodies or our living and working environments; there are ranges, and our bodies can and do adapt. If a child’s or a person’s temperature reads 38 C at a given moment, it doesn’t necessarily mean they are sick. And if the office thermostat reads 25 C, don’t rush to set it at 22 C; 24 or 25 C is a perfectly fine ambient temperature. It has been shown that people can work at up to 28 C and that an overly cold environment reduces productivity.

Health surveys have also reported that people who work in overly air-conditioned places visit doctors and hospitals more often and take more medical leaves. And people who use natural ventilation instead of artificial cooling of homes and workplaces report fewer colds, respiratory problems and allergies.

With summer starting and the pandemic slowly receding, let us try to adopt more rational attitudes with regard to temperatures and cooling.