With autumn comes the return of sniffles and runny noses. Why do we seem to “catch a cold” at this time of year? Your sneezing is not from lower temperatures: there are other explanations.
Your computer keyboard is lost under a pile of dirty tissues, your sniffles are already annoying your neighbors, your nose is blocked and your voice threatens to die out at any moment. While the temperatures have particularly dropped, in this early fall, you are one of the unlucky ones who have caught, not the coronavirus, but a cold. As the saying goes, you have ” caught cold “: a formulation that is not scientifically valid.
You don’t get nasopharyngitis because it’s colder outside. This statement is surprising, as the infection always seems to accompany the drop in temperatures and the arrival of the first flakes. It also arrives at the beginning of autumn, when we don’t know what to put on to face the cool temperatures in the morning, without being too hot the rest of the day.
The common cold is explained by temperature variations
The English translation of the word “cold” also contributes to maintain this received idea: in the language of Shakespeare, we use the word “cold” which also means “cold”.
The cold does not seem totally unrelated to this widespread respiratory infection: as noted by the American Lung Association, adults have on average two colds in the year, which most often occur between the months of September and May. The fact that it is the coolest time of the year is no coincidence, but it is not the low temperatures that explain why you get sick.
According to Faïza Bossy, a general practitioner in Paris interviewed by Numerama, colds are mainly explained by temperature variations. ” One can just as easily catch a cold in a hot country, if one is in an air-conditioned place. A variation of 3 to 5°C is difficult for the body to bear and can be the cause of cold symptoms “says the expert. Certain predispositions contribute to making us fall ill: When you are tired, for example, the body defends itself less well, because there is a decrease in immunity “, continues our interlocutor.
In winter, we gather in closed places
The popular belief that the common cold is related to the cold comes from the fact that cold-causing viruses predominate during the winter months in this part of the world “, explained Stan Spinner, pediatrician at the Texas Children’s Hospital, to the New York Times last February. Despite their greater presence, the viruses responsible for the common cold are not the only culprits: our tendency to containment during the fall and winter periods is responsible for the spread of the infection.
As our colleagues from the Huffington Post have pointed out, the drop in temperatures encourages us to adopt behaviors to avoid getting cold. Not only are we more likely to congregate in certain closed places (school, metro, restaurants), but these places are also less regularly aired. This leaves viruses free to spread between individuals, much more easily than if we were outside in the cold.
Faïza Bossy agrees and insists on the fact that the problem does not come so much from confinement, as from saturated air when the heating is poorly adapted. ” In a subway car, depending on how the air exchange is calculated, it will probably be well ventilated if there is only one passenger. With 100 people in the wagon, air renewal will be more complicated “, she tells us.
To understand why we catch colds so often during our lifetime, we must also know that the viruses carrying the infection exist in their hundreds: the American Lung Association has counted more than 200 kinds. Rhinoviruses are the most common: they find a perfect place to lodge in our noses, as their optimum growth temperature is 33°C.
The multitude of viruses that cause the common cold explains why it is difficult to find a real cure for the infection: you can catch very different viruses during your lifetime – even if their effects will always be the same.
In addition to the crowding and diversity of viruses that cause colds, there is another factor: the humidity of the air. In winter, the air is much drier: as a result, the nasal mucosa is more susceptible to viruses. Using the heater indoors makes the problem worse, as it dries out the sinuses and prevents nasal mucus from draining properly, and fighting off the virus.
In 2013, a study published in the journal PLOS established that a humidity level prevents the spread of influenza viruses: when they are expelled by a sneeze, they attach themselves to water molecules. If the air is dry, they make their way more easily to other individuals.
This is why we are more prone to infection in autumn and winter: it is not because we remain exposed for a while to cold temperatures. You will now know what to do if you are told not to go out without a sweater, because you risk ” to catch a cold. “Like Faïza Bossy, you can retort that” intense cold is not responsible for the common cold “.