There are plenty of times when you might wonder how far germs spread through sneezing and coughing. Maybe you’re sitting in a meeting when the person across from you sneezes so hard they may have shifted a few tectonic plates, spraying you with a fine mist in the process. Or perhaps the person next to you on a flight spends the entire trip coughing so intensely you worry they’re going to hack up a lung.
In a weird way, it can feel even worse when you’re the culprit. You can’t always control when your body decides to let ‘er rip. If a sneeze or cough sneaks up on you when you’re sick and you can’t cover your mouth and nose, are you going to infect everyone around you?
Here, doctors explain what you should know about how far germs spread when people sneeze and cough, how to keep yourself as healthy as possible, and how to protect others when you’re the sick one.
Infectious diseases have a few modes of transmission.
One of these is large droplet transmission, Alexander L. Greninger M.D., assistant director of the University of Washington Medicine Clinical Virology Laboratory, tells SELF. This refers to the droplets sick people expel when they cough, sneeze, or talk. If someone else inhales those secretions, they can get sick, too. Illnesses like the flu, the common cold, and pertussis (whooping cough) are thought to mainly spread this way.
Then there are infections that fall into the airborne transmission category, like measles, tuberculosis, and chickenpox. Unlike large droplets, which need to quickly come into contact with someone’s mucous membranes in order to cause an infection, airborne transmission allows potential pathogens to remain suspended in the air for some time after someone coughs, sneezes, or talks. (Remember, not all germs are actual pathogens that can make you ill.) Then someone else can breathe in those particles and get sick.
Some illnesses can infect people via both forms of transmission. For instance, the flu mainly spreads through large droplets, but the CDC notes that it can be airborne as well.
Infectious diseases can spread in other ways, such as through direct contact (like if you kiss someone who’s sick). But since we’re talking about how far germs spread through the air, we’re going to focus on large droplet and airborne transmission.
So, how far can germs actually make it through the air?
The important thing to understand here is that scientists really only have estimates for how far coughing and sneezing can spread germs, not hard numbers. Some of this might even depend on how forcefully a person coughs or sneezes. (Scream sneezers, we’re looking at you. But we also know it’s not your fault.)
Large respiratory droplets containing pathogens like influenza can travel up to 6 feet when a sick person coughs or sneezes, according to the CDC. A 2014 study by MIT scientists published in the Journal of Fluid Mechanics suggests this number may be way higher for smaller airborne particles. Researchers used high-speed video upwards of 1,000 frames per second to record sprays of mist as well as human coughs and sneezes, finding that smaller droplet particles traveled as far as 2.5 meters horizontally through the air. That’s more than 8 feet.
The study also recorded smaller airborne droplets spraying 13 to 20 feet vertically in the air, which researchers noted was theoretically high enough to enter and travel through some ceiling ventilation systems in some buildings. The researchers posit that this impressive (and kind of nauseating) distance is because smaller pathogens can travel as part of a buoyant cloud that extends their reach.
The problem with airborne pathogens isn’t just how far they can spread, it’s also how long they can hang out in the air and on objects. A lot of this depends on the pathogen in question. Measles, for instance, can live for up to two hours in the air and on surfaces, according to the CDC. This illness is so contagious that 90 percent of people who are close to a person with measles but who aren’t immune (like through vaccinations) will catch the illness. That’s especially scary considering the recent measles resurgence happening in some parts of the United States.
You’re not guaranteed to get sick if someone sneezes or coughs on or near you.
It’s normal to feel completely grossed out by how far germs may be able to travel. That still doesn’t mean you’re doomed to get sick, even if someone sneezes in your face. (Anyone else just full-body shudder?)
Yes, someone who is ill sneezing or coughing on or near you can boost your chances of getting sick. This is true even if you hold your breath. “The particles will stay there for many minutes, and in some cases many hours, and you can't hold your breath that long,” Keith Roach M.D., associate professor in clinical medicine at New York Presbyterian Hospital. Or you could rush away from the scene, but the particles may still be on your clothes, which you might touch later. You get the picture.
The good news is that even if someone sick sneezes or coughs around you, factors like your past exposure to viruses and your vaccination record could end up protecting you from that illness, depending on the strain in question. (Make sure you’re up to date on your flu vaccine every single year. Is it 100 percent effective? No. Does it still slash the death toll and number of hospital visits linked with the flu each year? Yes.)
If you have good hygiene habits, that’s another point in your corner.
Excellent hygiene practices may help you avoid getting sick.
Wash your hands, people! Soap and water are most effective at preventing transmission of illnesses like the cold and flu, but Dr. Roach recommends keeping alcohol-based hand sanitizer at the ready for the times you can’t wash your hands. Your sanitizer should be at least 60 percent alcohol in order to be as effective as possible. Even with great hand hygiene, you should try to avoid touching areas like your mouth, nose, and eyes, since those are possible portals for pathogens. That stands whether or not your entire office has come down with the flu.
Finally, Dr. Greninger recommends prioritizing lifestyle measures that can help your immune system work as well as possible, like getting adequate sleep. Eating in a way that fuels you and trying to manage stress are good ideas, too. (When possible, since we know it’s not always.)
If you’re sick, cover your face when you sneeze and cough.
This can definitely be helpful in sparing others from your illness, Dr. Greninger says. Just don’t cover your face with your hands, because that makes it all too easy to spread those germs around. Instead, the CDC recommends coughing or sneezing into a tissue and then throwing it away, or sneezing into your upper shirt sleeve or elbow, completely covering your nose and mouth.
Unfortunately, even the best cough and sneeze etiquette can’t fully stop the spread of disease, Dr. Roach explains. A small 2013 study of 31 people published in BMC Public Health found that some droplets—especially smaller ones—still spread when the participants were practicing good cough etiquette, including coughing into their shirt sleeve or elbow.
As the scientists explained, this is because some particles manage to find the path of least resistance around whatever is blocking them. But pure physics dictates that putting an obstacle in the way of any pathogens is preferable to just spewing them into the air without any barriers. Even though covering your nose and mouth isn’t foolproof, it’s definitely better than nothing—which is precisely why the CDC recommends it.
In addition to following proper sneeze and cough etiquette, you should wash your hands thoroughly and frequently when you’re sick. (Especially if you slip up and cough or sneeze into your hands.) It’s also kind to try to keep your distance from people when you’re ill, including staying home from work if you can when you’re really sick, and to frequently disinfect surfaces you’re always touching.
In situations involving compromised immunity, face-blocking devices may help.
If you’re sick and spending time with people who have compromised immune systems, or if you have a compromised immune system yourself, you may want to step your illness prevention up a notch. Depending on your specific scenario, it could make sense for you or the people around you to wear a device like a face mask or N95 respirator.
Face masks can block many large droplets, while N95 respirators are designed to obstruct the passage of those very small airborne particles that can lead to illness, according to the Food and Drug Administration (FDA). But a 2011 systematic review published in Influenza and Other Respiratory Viruses, which looked at 17 different studies, suggests that these devices are much more likely to help prevent illness if worn consistently and correctly. If you’re curious about these illness-preventing measures, talk to your doctor for advice and guidance on proper usage. And even if you do opt to use these, you should still practice the above measures to make sure you—and those around you—can remain as infection-free as possible.