So I have this thing with germs. As in: when I’m in a public space, I can’t stop thinking about all the germs I’m picking up. Especially when a place just looks, well…germy. A place like the inside of a CTA train car.
Don’t get me wrong. I love the train. Public transportation is my jam, which is why I’m embarrassed to even admit that I get kinda grossed out by it. It was time to either validate or dismiss my concerns — with science.
So, I spoke with an expert to figure out whether riding the L is as unsanitary as I thought.
ERICA HARTMANN: My name is Erica Hartmann, and I am an Associate Professor of Civil and Environmental Engineering, and my lab does a lot of things, but we are primarily interested in environmental microbiology and how the microbes around us react to things that we do, like cleaning, and how that impacts public and environmental Health.
GEORGIA KERRIGAN: So I’m not gonna lie, I literally had to look up right before this, what are microbes? So can you break down some of the technical terms for me, like I wrote down, what are microbial communities?
HARTMANN: Okay, so I think when a lot of us think about microbes, we think about like maybe E coli growing on a petri plate, kind of thing. But in nature, most microbes don’t exist on their own. They exist in really complex community structures where there are lots of different types of microbes doing lots of different things. So a good example of that might be like the gut microbiome. So you have tons and tons of microbes in your gut that are doing lots of different things to help you digest your food, and you need different microbes to digest different parts of your diet. And then those microbes are really important, because they actually are digesting a lot of the things that you eat that you physically cannot digest on your own. So a microbial community is a group of different microbes, so that can be bacteria, archaea, fungi, even viruses, and we find microbial communities everywhere, including inside us.
KERRIGAN: When do they become bad for us? You know, what’s like a bad microbe? Or where do we find that?
HARTMANN: Yeah, so there are trillions and trillions of different types of microbes out there, and a really, really small handful of, like, bad microbes, but they’re, of course, the ones that get all the press. So if we think about, for example, even E coli, like, whenever there’s a food recall for contaminated produce or something, and they’ll say, oh, it’s E coli. Actually, there’s E coli everywhere, all the time, and most of it is totally fine, and only some of it will actually make you sick. And it depends on both some factors about the E coli itself, like whether or not it produces toxins, and some factors about you and like how healthy you are and how healthy your microbiome is. So most bacteria won’t make you sick at all. Many of them are essential, like I said to like, keep us healthy and happy. The ones that will make you sick, they won’t necessarily make everyone sick in the same way.
We also have microbes on our skin that actually help keep your skin healthy and happy, and they do a lot of different things on your skin. One thing that we think they’re doing is basically occupying territory to prevent infection. So if you have this robust microbial community that’s hanging out on your skin, and they’re they, you know, they’ve set up shop there, and they’re using all the resources, and they’re taking up all the space. If a pathogen were to come in and try to make you sick, basically, it would have to fight the other microbes that are already there first. So we think they’re really helpful.
You probably already know this. If you think about like, the skin on your forehead is probably a little bit oily and the skin on your elbow is probably a little bit dry, that actually creates a different environment for microbes, and then you find different microbes that will live in these different environments. And this is really important, because we take our microbes everywhere we go, you can’t leave them alone. And just the same way that you might shed, like dead skin cells or hair or things like that, when you walk around, you’re also shedding those microbes. And so a lot of the microbes that we find in heavily human-occupied spaces, like on transit or in planes, tend to reflect the fact that people are there, and people have brought their microbes there, and so you see a lot of skin-associated microbes on those surfaces.
KERRIGAN: So we’re just constantly shedding, swapping, picking up microbes from other people, other surfaces?
HARTMANN: Yes, exactly.
KERRIGAN: That’s weird to think about.
HARTMANN: It’s weird to think about, but it’s actually probably also really important, because in addition to helping us digest food and keep out pathogens, another thing that microbes do is help maintain our immune system. So if you don’t have exposure to microbes, the thought is that that actually creates an overreactive immune system, and then you wind up with, like, autoimmune conditions and allergies, and we don’t fully understand exactly which exposures you need, when, and how. If we did, someone would probably already have a whole treatment available, but, um, but it does seem like not getting enough microbial exposures can actually have negative health impacts.
KERRIGAN: Does that kind of translate into, don’t over-sanitize things?
HARTMANN: So a lot of my research actually focuses on exactly that question, of like, what happens when you use cleaning products, and what really are the impacts of sanitizing practices? So I’m interested in this for a couple of reasons. One is that microbes are incredible and will find a way to survive just about anything. So much in the same way that bacteria can develop resistance to antibiotics, they can also develop strategies to survive, things like cleaning and sanitization. So every time you clean something, it’s not like you get rid of all of the microbes there. You get rid of a lot of them, but you’re actually then just changing the types of microbes that you’re exposed to. So that’s one thing.
The second thing is that the chemicals that you use to clean with, especially antimicrobials, are things that are harmful to life forms, and those chemicals don’t just vanish. You’re then exposed to those as well, and that’s not necessarily a good thing. And so when we’re thinking about cleaning, what we really want to think about is, what are the microbes that are there? Are they a problem? And is being exposed to the cleaning product better than being exposed to the microbes?
KERRIGAN: I think about germs a lot. And when I ride the train, I always come home, and the first thing I do: I take everything off, I shower, I put everything in the laundry. Just, the thought of germs on me, I’m like, ‘Oh, I just rode the train. I just touched hundreds of people today.’ You know, how worried should we actually be about that?
HARTMANN: I’ll give you a data answer and a feels answer. All right, so my data answer is not so much to do with surfaces, but to do with COVID. So someone did this, basically this modeling study of exposure to say, you know, if you think about the time that you spent in, for example, in a bus. So, in transit versus in, let’s assume you worked in an open plan office, that the amount of microbial exposure that you would be getting from the air and the bus is actually much less than what you would be getting from spending whatever, like your eight hours in this open plan office. So think about that, for example, a classroom, right? Maybe a lecture hall with a couple 100 people in it, that maybe you’re stuck in for an hour and a half, that kind of thing. Like, if you think about the magnitude of that exposure versus the magnitude of exposure in a not super-packed train car. And so I would think about it that way, that there’s nothing unique about transit that makes it inherently riskier than any of the other sort of public activities that we’re engaging in, like going to work, going to school, going the grocery store, that kind of stuff.
So the feels answer, this is the other thing is, like I said, there are two parts to the equation. Of like, there’s stuff about the microbe, where some microbes make toxins and some microbes will, you know, be worse for you than others. But there’s also this like component that is about you and how healthy you are. And we all know that, like, your immune system sort of waxes and wanes as you’re stressed or tired or not eating right, or things like that. And so the other thing about like planes or transit is, if it’s really, really stressful for you, you might actually then be more vulnerable in that moment than you would be somewhere else. So I would think about that sort of part of the equation. And actually, this is where it gets a little like, flipped is like, if you are really thinking about it and really, like, psyching yourself out, you might actually be making it worse for yourself than if you were to just, like, be like, ‘Oh, I’m on the train. No big.’ But that’s my feels answer. There’s no data behind it.
And if you think about just like the millions and millions of people who use transit all around the world every day, if there was something about transit that was actually making you sick, we would know. I know that CTA really amped up their cleaning protocols for a while, and I don’t know how they are now, compared to pre-pandemic. But again. It’s the kind of thing where, like, think about, do you really want someone going in with one of those chemical foggers and, like, spraying a bunch of reactive chemicals that might then actually, let’s say you have asthma, trigger your asthma, versus, yeah, maybe you encounter some microbes that were on somebody else’s skin.
I have asthma, so I think I’ll take the microbes that were on somebody else’s skin.
Of course, though, I still had to look up the CTA’s cleaning protocol for some more peace of mind. According to the CTA website, the rail cars are cleaned daily, plus, they get monthly deep cleans and power-washing. Whether that cleaning is doing more harm than good is a question I’ll leave for Hartmann. Personally, I still like a car that at least seems clean.
And if you’re also a bit of a CTA germaphobe, I’ll leave you with Hartmann’s parting advice for me: “Make peace with the microbes.” Because…
KERRIGAN: There’s microbes everywhere.
HARTMANN: There’s microbes everywhere.
For WNUR News, I’m Georgia Kerrigan.
