Does Cold Air Kill Germs? What About Heat?

Here's a common question: Can a cold or hot air kill germs It's that time of year again where your nose will be dripping out of control. While you're having your sneezing frenzy, ever wonder why does the flu spread in the winter? Shouldn't the freezing cold temperature kill the germs and end the flu epidemic? If cold can't kill bacteria and viruses, can heat do the job? Don't worry as we have all the answers here. Any questions involving temperature, germs, and weather will be addressed below.
Short answer
Cold air will not kill germs but heat will.


Does Cold Air Kill Germs?

Cold air and snow do not kill germs, bacteria, or viruses. Most germs will stay dormant in freezing temperatures until the membranes inside break, dry off, and die (under extreme weather). Germs like the flu virus are more cold-resistance where they can thrive in cold weather during the winter season. Another common problem is bacteria and viruses may have already found their way into a host warm body. Our human body will provide the right temperature plus nutrients for the germs and shield them from the outside cold weather.

Do Germs Spread Faster In Cold Weather?

Germs, bacteria, viruses will spread faster in cold weather. This is because cold air will actually protect the virus by forming a hard, outer layer of envelope gel. The protected virus will stay longer in the air thereby increasing the risk of a person inhaling it. Dry air with very little moisture is another common theme in cold weather. When the humidity level is low, air droplets are small and light making it easier for germs, bacteria, and viruses to airborne spread.

If the weather drops down to a freezing temperature, some germs will slow down, stay dormant, or even die. Germs that survived through freezing weather will begin multiplying when thawed due to the increased temperature. For example, Influenza (flu) or Rhinovirus (cold) will thrive and multiply in cold temperatures.

Cold weather on its own will not make us sick however, it can dry out our nasal passages and mucous membranes making it more vulnerable to virus infection. A good indication of germs transmitting rapidly in cold weather is people tend to catch a cold or seasonal flu during the winter months.

Does Heat Kill Germs?

According to WHO, Germs, bacteria, and viruses can be killed through heat at 140º F or higher. Heat will break down the molecule structure of germs thus disabling their functionality. The higher the temperature, the faster germs will be killed. Hot bath or shower is not hot enough to kill germs and the dampness will help the growth of mold. UV-light or sterilizer will be a better choice in eliminate pathogens via ultraviolet light by damaging their DNA. There are few exceptions though. Germs like hyperthermophilic bacteria can grow in very hot temperatures up to 250°F degrees. Fortunately, those germs are rare and few that you should not be alarmed about.

Do Germs Spread Faster In Hot Weather?

Hot weather can kill or slow down most germs, bacteria, viruses from spreading. When exposed to high temperatures, the outer protective capsule of the viruses will melt and expose the fragile body. This causes the protein in the germs and viruses to denature or lose its functional form. Respiratory droplet formations are also the reason why germs spread slower in hot air. As hot weather can be extremely humid e.g. in the summer, droplets are larger and heavier making it hard for the germs to transmit. Airborne germs and viruses will also drop faster due to extra weight. Keep in mind that some viruses can adapt to warm temperatures better than others so proper hygiene is still the safest solution.

What Temperature Kills Germs In The House

Most germs will die from 165 degrees F to 250 degrees F (121°C) within a couple of minutes. That’s the recommended temperature from food scientists to heat up meat, fish, pork before serving. Some viruses can be killed at temperatures 140 degrees F (hot water). For dry heat sterilization, switch the temperature to 320 degrees F (160°C) for 2 hours or 338 degrees F (170°C) for 1 hour.

Take note that not every heat can kill germs. Also, water that has been boiled is much safer to consume than hot water. The higher and longer the germs are under extreme temperature, the faster and more germs will die.

How To Keep Germs From Spreading Around

So no matter how hot, cold, or dry the air is, there will always be germs around. Remember, germs, viruses, and bacteria will react differently to cold or hot temperatures. Germs will also have different life expectancies to be transmissible when living on different surfaces. Most germ flu will live up to 3 days or 72 hours on hard surfaces like stainless steel and plastic. The same germ flu will only live up to 24 hours on paper or cardboard. On fabric surfaces like clothes, pillowcases, bedding, flu viruses can live 8 to 12 hours depending on temperature and humidity. For example, germs in a wet towel will survive longer than a dry towel.

Even though most germs are bad for us, there are studies that show exposure to germs can help strengthen our immune system. That doesn’t mean we should openly expose ourselves to bacteria and viruses. Precautionary measures and good hygiene is the best way to protect us from falling sick to germs.

For contaminated clothes or upholstery, hot temperature is preferred over cold. you can kill germs by washing them in high heat temperatures around 140°F to 150°F together with detergent. After that, dry it with a tumble dryer and high heat at around 150°F to completely disinfect bacteria, fungus and prevent further growth.

For dishes, you can wash and rinse them with hot or cold water. The best way is to use a dishwasher that can output hot temperatures to sterilize dishes from bacteria. You can still clean and rinse the dishes through hand wash but preferably with hot water at 113°F.

For food-related bacteria like Legionella, cooking will do the trick as germs can be killed through boiling hot water, pasteurize, or baking with an oven. Most canned foods are prepared at high temperatures to ensure no germs are left in the can. That said, you should always keep food refrigerated as bacteria thrive between 40º F to 140º F. There are extremophiles microorganisms that can survive in extreme temperatures and conditions. Thankfully, those are the rare few that we don’t encounter very often.

Ultimately, practice good hygiene is the key to avoid infection. The best way to protect yourself from germs, bacteria, and viruses is to wash your hands frequently with soap and water. Wash your hands for at least 20 seconds especially after using the restroom, cooking, changing diapers, touching animals, and grocery shopping. Doesn’t matter if is cold or hot water you are washing your hands with, as long as it can get the dirt and germs off your hand. Once your hand is completely cleaned, dry them thoroughly with a cloth or paper towel. You can also clean your hand with alcohol-based hand sanitizer when you’re outside. By keeping your hands clean, you are reducing the risk of germs been transferred to your eyes, mouth, and nose via touching.

[UPDATE] A lot of readers that landed on this page is actually seeking for more information on Coronavirus disease (COVID-19). Here are the verified facts according to World Health Organization (WHO).

  • The coronavirus disease is caused by a virus in a family called Coronaviridae, not by bacteria.
  • Taking a hot shower does not prevent you from catching COVID-19 disease. Normal body temperature will be around 97°F (36.1°C) to 99°F (37°C) regardless of the temperature of a bath or shower.
  • Cold weather and snow do not kill the coronavirus or any other diseases. External temperature or weather does not affect our normal body temperature.
  • You can still catch COVID-19 under hot weather. Exposing yourself under the direct sun with temperatures higher than 77°F (25°C) does not prevent coronavirus disease.
  • COVID-19 virus can be transmitted in countries with hot and humid climates like Thailand, Malaysia, Indonesia.
  • Ultraviolet light should not be used to disinfect hands or other parts of our body as the UV radiation can cause skin irritation and damage to eyes when pointed straight at.
  • Hand dryers are not effective in killing the coronavirus even at the highest setting.

For the latest updates on COVID-19, please go to World Health Organization (WHO) website.

Here's some scary stats about flu from CDC. 5% to 20% of the U.S. population gets the flu every year. That's 9.3 million to 49 million of illness cases since 2010. Flu results in 31.4 million outpatient visits and more than 200,000 hospitalizations each year. 58% of the deaths occurred in adults are age above 65. The flu costs an estimated $10.4 billion annually in medical bills. It also affects employees to miss around $17 million of workday. In 2017-2018, the flu vaccine is rated at 40% effectiveness and prevented 5.3 million illnesses.

Does Fresh Air Kill Germs?

There is research that shows outdoor fresh air is a natural disinfectant that will kill germs and bacteria. That said, the research clearly identifies sunlight contribution as a germicidal to kill the flu viruses. Enclosed areas like the bedroom, basement tend to have poor air quality as the air is filled with germs that are passed on from various sources. By opening windows to improve room ventilation, you are airing out the stagnant air and letting fresh air in that has been disinfected by the sun.

Why Do We Get Colds In Winter?

The reason why we always get colds and flu in winter is because of the lack of outdoor activities. Cold weather weakens the body’s defenses against infections. We will spend more time indoor with poor air circulation surrounded by people that may be sick. For instance, shopping malls, cinemas, cafes, train stations will be packed with people that are carrying germs. Germs are often passed from a person to person through cough, sneeze, or simple gestures like shaking hands, hugging. You will likely catch a cold through direct contact than with a fresh airborne virus.

Another reason why colds and flu are more prevalent in winter is the lack of natural sunlight. Sunshine can kill bacteria and viruses according to many studies. As the density of airborne germs is less, our exposure rate to the microorganisms would also decrease. Bacteria and viruses tend to live longer indoors during winter as the air is less humid than outside.

From the doctor's perspective, the body's immune system tends to wear down in cold weather as we are running low on vitamin D (sunlight). When we breathe in cold air, our blood vessels will thicken to help retain our body heat. This causes the white blood cells to ignore the harmful viruses and we end up with bad flu like influenza.

How To Avoid Getting Sick In Winter

Germs love indoors as it is the best place for the flu to spread. So to prevent flu from spreading too much love, here are tips that will protect yourself from viruses and prevent you from falling sick to the viral flu.

  1. Get a humidifier - A humidifier can resolve dry air conditions by dispersing water vapor. By maintaining the room humidity level between 30 to 50 percent, our nasal passage will be kept moist and protected against germs.
  2. Take Vitamin D supplements - The days are short during the winter and the lack of sunlight will contribute to the low levels of Vitamin D. Vitamin D can help boost our body's immune system against germs and viruses. Take 600 to 2,000 IU of vitamin D3 a week to reduce the chances of catching a cold and flu up to 70 percent.
  3. Get some fresh air - Especially during the cold winter seasons as viruses are often spread airborne from person to person that is carrying the germs. Most people will spend their time cooped up in an enclosed area. Whenever possible, go for a long walk instead of staying at home the whole day.
  4. Get an air purifier with UV light - Germs can stay suspended in the air for days until it is inhaled or ingested. An air purifier will trap and eliminate airborne bacteria and viruses 24 hours a day without fail.
  5. Stop touching yourself - Viruses and germs often pass from hand to mouth. Avoid touching your face, nose, rubbing your eyes, biting your nails, and wiping your mouth. Sanitize your hand as frequently as possible. Also, keep social distancing with minimal contact from outsiders. Physical contact is the leading cause of virus spread.
  6. Disinfect everyday items - Any surface objects will have the risk of germs contaminated through indirect contact transmission. Disinfect items you touched every day like a doorknob, remote controls, keyboards, handles, and so on. There are no short of disinfectants in the market that are specifically designed to kill harmful bacteria, viruses, and germs. Sanitizers can quickly remove germs like soap while disinfectants kill germs permanently.
  7. Exercise regularly - At least 3 times a day for 20 minutes. It can improve the body immune system and upper respiratory tract from infections.
  8. A good night sleep - Between 6-8 hours without any interruption. A person with consistent quality sleep is 28% less likely to catch a cold.
  9. Eat protein-rich foods - With milk, eggs, fish, and greek yogurt. Yogurt is our favorite as it contains a strain of probiotics that will boost our body's defense against viruses.
  10. Take flu shots - Influenza vaccines can be taken annually to protect against infection like influenza viruses.
  11. Don't smoke or hang around with smokers - Smoking increases your chance of respiratory infections. You will be more vulnerable to seasonal cold, influenza, or H1N1 (swine flu).

Max Fernandez

A loving father and a dedicated reviewer for airfuji.com with more than 1000 air purifiers under his belt. Max Fernandez is also one of the million patients currently suffering from asthma. Feel free to nudge him if you have any questions.
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