For years many people have believed that being out in colder weather increases your chances of becoming sick. It does appear to be true that more people are “sniffling” and coughing in the cold winter season. Also, flu season falls in colder months and peaks in January and February, which are the coldest months of the year. For many people, this certainly raises questions as to why many people get sick in the cold months of the year. Could the cold air itself be the result of this?

NO! It is a common fact that germs and bacteria get you sick, not the air. However, there are multiple explanations that can explain more people getting sick in the colder months.

First, scientists have discovered that cold air does help the flu virus flourish, but is not the cold air itself that gets you sick. In a study done by the National Institutes of Health, they found that in colder temperatures, the outside most layer of the virus hardens and becomes more of a gel or rubber like surface. This allows it to travel from person to person much easier in cooler temperatures because it can brace the elements. Adding onto this, they also discovered that in hotter temperatures that same outer layer turns into more of a liquid substance, which simply cannot survive in the elements of nature. Further, this explains why flu season exists in the colder months of the year.

More recently, another study could also explain why more people get sick with the flu in the colder months. In this new study, NIH researches compared data over the last 31 years. They were searching for some type of correlation between the number of deaths from the influenza virus (flu) and the levels of humidity. They actually found something. The researchers discovered that before a flu outbreak, the absolute humidity levels in the air fell. This suggests that in dryer air, the virus is transmitted much easier allowing it to infect more people. Further, this also helps explain why there are more flu outbreaks in the winter because typically in more colder regions, the air is dryer in the winter.

There are also more obvious reasons as to why more people get sick when it’s cold out. When it gets cold outside, most people stay inside. This is a problem because we often are around more people inside where air is being recirculated so it is easier to become in contact with germs and bacteria. It is also easier for the bacteria to be transmitted indoors because it does not have to withstand the elements of nature. So, even though it may seem like colder air causes people to get sick, science has been able to prove otherwise. Another classic example of correlation does not equal causation.

Sources:

https://www.nih.gov/news-events/nih-research-matters/dry-air-may-spur-flu-outbreaks

https://www.nih.gov/news-events/nih-research-matters/flu-virus-fortified-colder-weather