Does Cold Air Make You Sick?

Cold air cannot make you sick, but the odds of catching the common cold or influenza (the flu) are highest during the fall and winter.

Although cold weather doesn't cause a cold or the flu, it can set the stage for certain factors that decrease your immunity and increase opportunities to catch these illnesses.

This article explores the factors associated with cold weather that increase the chances of getting sick.

Child blowing nose into tissue
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Cold, Dry Air Affects Virus Spread

There is some evidence to suggest that viruses spread more easily through cold, dry air. Temperature and humidity, therefore, may affect your risk of catching a virus.

When it is cold outside, the air is drier both outdoors and inside (due to heating), drying out mucous membranes and making it easier for germs to take hold.

The nose is an ideal host for many viruses due to its cooler temperature. The typical core body temperature is 98.6 degrees F, but the nasal cavity temperature is lower at 91.4 degrees F. Research suggests that rhinoviruses (viruses that cause the common cold) do not replicate efficiently at body temperature, but the cooler temperature in the nose may make it an ideal breeding ground for viruses.

One study suggests colder temperatures on their own do not increase the spread of colds and flu, but temperature and humidity fluctuations do. Researchers cross-referenced confirmed cases of rhinovirus with weather data over a set period of time and discovered that decreases in either temperature or humidity over a three-day period increased the risk of rhinovirus infections. 

The study, which involved 892 men in the Finnish military, also suggests that breathing cold air may contribute to the spread of infection into the lungs. This is based on earlier research that found lung temperature can be lowered by inhaling cold air. However, researchers also noted that the risk of rhinovirus infection is reduced at subfreezing temperatures and higher humidity.

Warmer air does not necessarily kill viruses, either, as is evidenced by the spread of colds and flu in tropical areas where it does not get cold. Cold and flu cases are more prevalent in tropical climates during the rainy season. This is likely due to people spending more time indoors when it's raining, putting them in closer contact with others than during the dry season.

Cold and flu symptoms are caused by more than 200 different viruses that spread from person to person. The influenza virus responsible for the seasonal flu spreads across the United States from October to April.

Rhinovirus has more than 150 different circulating strains at any given time and accounts for more than half of all colds each year. Various strains of coronavirus, enterovirus, parainfluenza, and respiratory syncytial virus (RSV) can cause different degrees of congestion, fever, cough, and body aches. 

Reduced Immune Function

People may also be more prone to catching a cold or flu in the winter due to lower immunity. Fewer daylight hours and less time spent outside mean less exposure to sunlight, which the body uses to make vitamin D. In addition, lack of activity during cold weather may also mean reduced immunity.

Vitamin D

Vitamin D plays a critical role in the immune system helping to keep you healthy. Vitamin D deficiency is linked to an increased risk of viral infections, including those in the respiratory tract.

Researchers are studying whether vitamin D supplements can help improve immunity when vitamin D levels are low. A review of 25 studies concluded that vitamin D supplementation was safe and it protected against acute respiratory tract infection. People who were very vitamin D deficient and those not receiving high single doses of vitamin D experienced the most benefit.

Lack of Exercise

People also tend to be less active in cold weather. While it is not clear exactly if or how exercise increases your immunity to certain illnesses, and no solid evidence, there are several theories, about exercise, such as:

  • It improves circulation, allowing white blood cells to detect and fight an infection faster.
  • It increases body temperature during and right after a workout, which may work like a fever to prevent bacteria from growing.
  • It may help to flush bacteria from the lungs and airways, reducing your chances of getting sick.
  • It lowers levels of stress hormones, which may protect against illness. 

Close Contact During Colder Months

Viruses rely on the cells of other organisms to live and replicate. They are transmitted from host to host when infected respiratory secretions make their way into the mucous membranes of a healthy person. How transmission occurs may include:

  • Direct person-to-person contact, such as hugging, kissing, or shaking hands
  • Inhaling small droplets in the air from a sneeze or cough
  • Touching something that has the virus on it (like a doorknob, drinking glass, utensils, or toys) and then touching your mouth, nose, or eyes

It logically follows, then, that the closer you are to people and the more you share a space, the more likely transmission is. In the winter, many people tend to take their outdoor activities inside. For example:

  • School recess being held in a gym, rather than outside
  • People walk around crowded shopping centers rather than on a track or neighborhood
  • People staying indoors more hours of the day

This close contact during colder months increases the likelihood of passing germs.

Protection From Cold and Flu

The most important thing to remember during cold and flu season is to protect yourself and stop the spread of these germs when you are around other people. Steps you can take to prevent cold and flu include:

  • Wash your hands often or use an alcohol-based hand sanitizer if soap and water aren't available.
  • Avoid close contact with people who are sick.
  • Stay home when you are sick.
  • Cover your mouth and nose with a tissue or the inside of your elbow when you cough or sneeze.
  • Wear a face mask in crowded places.
  • Try to avoid touching your eyes, nose, or mouth as much as possible, since that is how most respiratory germs enter the body. 
  • Clean and disinfect frequently touched surfaces at home, work, or school, especially when someone is sick.
  • Get your yearly flu vaccine and any other recommended vaccines.
  • Get enough sleep.
  • Exercise regularly.
  • Drink plenty of fluids.
  • Follow a healthy diet.

Summary

Viruses make you sick, not cold air. However, exposure to cold weather can increase the chances of getting a cold or the flu. Viruses may survive and reproduce more effectively at colder temperatures, making it easier for them to spread and infect more people. Cold weather may also reduce immunity and keep us inside more, both of which make it harder for the body to fight off germs.

Fortunately, there are many preventive steps you can take to reduce the likelihood of getting a cold or the flu during cold weather.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Kristina Herndon, RN
Kristina Herndon, BSN, RN, CPN, has been working in healthcare since 2002. She specializes in pediatrics and disease and infection prevention.