Perhaps you were as grossed out as we were by that recent Weill Cornell Medical College study that showed New York City's subway system to be teeming with bacteria. Over an 18-month period, geneticist Christopher Mason and his team collected DNA from handrails, kiosks, seats, and turnstiles across the MTA to reveal a lush, invisible ecosystem containing more than 15,000 different kinds of microbial life. Ick, right?
Thankfully, the study also showed that the vast majority of bacteria found in the subway were harmless or even beneficial to humans. These “good” bacteria might come from food, remove toxins from the environment, or outcompete disease-causing pathogens lurking on surfaces. “That means more [bacterial] diversity, by the odds, would be a good thing,” Mason says.
Still, here at CityLab we have to admit to falling prey to dubious germaphobic behaviors, especially during cold and flu season. None of us has started wearing a surgical mask to work or anything (yet!), but at least some of us do things like flush public toilets with our feet, use tissues to open certain doors, and slather on what has to be far too much antibacterial gel. And the worst part is, none of us can really say whether doing any of this stuff actually works.
So we asked Mason and Dr. Martin Blaser, an epidemiologist at New York University, to tell us how much disease we're really preventing with some of our most common germ-avoidance maneuvers. (Spoiler: not much.) Keep these caveats in mind next time you reach for the Purell.
It's true that when you grip a subway pole or a door knob with a gloved hand, the germs transfer to your glove instead of your skin. This might, in fact, temporarily insulate you from live bacteria that prefer to grow on human skin or metal and fare comparatively worse on fabric. “There is some protective element of gloves insofar as it potentially takes a living organism and puts it onto an inert surface [where it] maybe wouldn’t survive,” says Mason.
However, some species fare just as well on gloves as they do on skin. And if you touch the outside of your gloves with your fingers or mouth, you’re right back where you started. Either way, any bacteria on your gloves will die in a day or so, or as soon as you wash them.
Holding your breath after someone coughs or sneezes
“If the cough has occurred already, it’s probably too late,” says Blaser. “The particles travel very fast.” Once germs are in the air, holding your breath will furnish little to no benefit. It might reduce your exposure to the pathogens floating directly in front of your face, but you don’t have to inhale a virus to get sick from it. Particles could still land inside your nose or on your eyes and lips.
“I can confirm that one way to almost guarantee that you won’t get any influenza in your lungs is to not breathe,” Mason says. “But if you don’t ever breathe, you will be dead eventually. … The cons definitely outweigh the pros.”
Wearing a surgical mask
A mask will reduce your intake of germs through the nose and mouth, but not by much. Surgical masks are not airtight, so they won’t seal out 100 percent of germs. However, if they’re worn by people who are already ill, they can promote public health by warning others to keep their distance.
Grabbing with paper towels or tissues
Using a tissue to open a door will reduce your physical contact with germs on surfaces, just like wearing gloves, but if you just wad the paper up and put it in your pocket, it’s no use (not to mention wasteful) because you’ll end up touching whatever the paper touched. For this method to be effective, you’d have to know and practice sterile techniques—for instance, taking your gloves off the right way so that you don’t re-contaminate them. There’s also the possibility that the paper is more absorbent than your own skin.
Touching surfaces with your wrist or the back of your hand instead of your palm
Touching a handrail is “like shaking hands with 10,000 people,” says Mason—but not all skin surfaces are created equal where bacterial transmission is concerned. Scientists have shown that the fist bump is more hygienic (that is, it transfers fewer bacteria) than the handshake, presumably because it exposes a smaller skin surface area.
That doesn't mean you need to start pounding it with subway handrails, however. Any difference in infectious disease risk is negligible at best—and certainly not worth the risk of wiping out in the car.
Hovering over the toilet seat
Let’s set aside for the moment the fact that you should never ever do this, as a cardinal rule of bathroom etiquette—and consider, for the sake of argument, that you’ve decided to suspend your buttocks above the seat. This will in fact allow you to avoid physical contact with the germs on the toilet seat. But no matter what you do, the contents of the toilet bowl will become aerosolized when you flush. “There’s a small mister of everything that was in that toilet ... in the air very close to you,” Mason says. “Some of it’s gonna land on you anyway.”
Putting the lid down when you flush can help a bit here. But, Blaser says, the chances of catching any kind of illness from a toilet seat are “infinitesimally small.” You have a much better shot of getting sick from ingesting fecal bacteria than from sitting on it.
Kicking toilet handles to flush
Again, this just keeps germs on the bottom of your shoes and off your hands. You’ll still have to deal with that “mister” of toilet slurry when you flush, and as soon as you get home and take off your shoes, those germs will end up on your floor.
It's totally fine to flush with a hand as long as you wash your hands afterward—which you should be doing anyway.
Using liquid hand sanitizers
Alcohol-based hand sanitizers are just about as effective against germs as soap and water. They're also easier on your skin than hand-washing, and unlike antibacterial soaps, they don’t breed antibiotic-resistant superbacteria.
In general, you shouldn't worry about using Purell immediately after exposure to pathogens. As long as you don't touch your eyes, mouth, or any other mucosal surface, you should have plenty of time to wash away the germs—anywhere from five minutes to five hours for bacteria.
On the other hand, excessive removal of bacteria, either with soap or hand sanitizer, may hinder your body’s natural ability to fight off infection. “Remember, your skin has its own bacteria, and they don’t really want to share the niche with the invading bacteria,” says Blaser. Scrub away too much of these bacterial defenses, and you’ll actually be more vulnerable to disease.
Mason says that instead of trying to kill all bacteria—which, even if it were possible, would not be desirable—we should focus on “enrich[ing] our skin, and also our buildings and our cities, for good bacteria.” That could mean everything from installing probiotic surfaces to designing ventilation systems with microbial filtration in mind. Research into the biology of the built environment is evolving and could have wide-reaching impacts on future building design.
What actually works
The bottom line is that you shouldn't live in fear of high-traffic surfaces. According to Blaser, this type of contact simply isn't the way people get sick. “We don’t get much disease from surfaces,” he says.
There is no evidence that subway handholds and toilet seats are significant transmitters of disease. There is no evidence that people who commute by public transportation are more likely to get sick than people who drive. And there is no evidence that health care workers are sicker than anyone else—even though they're constantly exposed to life-threatening pathogens.
That's because it takes more than the presence of bacteria or viruses to cause disease. “Many people think that the presence of an organism is tantamount to risk of disease, but it’s not,” says Blaser. “Presence has to be there, but the risk of disease can be infinitesimally remote—so remote, in fact, that it approaches zero.”
The risk is greater during cold and flu season, however; that's when it pays to practice extra vigilance. Purell is especially effective when there are a lot of people coughing and sneezing and a high concentration of germs in the air. But in times when most people are healthy, Blaser says, it's not clear that it offers much benefit.
There are some simple things you can do to help prevent illness: Wash your hands before you handle food and after you use the bathroom. Avoid people who are sick. Don’t smoke, which lowers your immunity. Don’t bite your nails or touch your face, the main entry point for germs. And, most importantly, maintain healthy habits: eat right, exercise, and get plenty of sleep. Those are the best ways to support your immune system. Using your palm to grip a subway pole doesn't have anything to do with it.