5 ms·

Respiratory virus pathogens on frequently touched surfaces at airports

50 points by uptown 8y ago

wahern 8y ago
Steel is one of the worst surfaces when it comes to harboring pathogens. AFAIU silver and copper are the best. Brass and bronze come in a distant 2nd (in absolute terms) but still significantly better than steel, where pathogens linger subject only to the external environment. See, e.g. https://en.wikipedia.org/wiki/Oligodynamic_effect https://en.wikipedia.org/wiki/Oligodynamic_effect and https://en.wikipedia.org/wiki/Antimicrobial_properties_of_copper https://en.wikipedia.org/wiki/Antimicrobial_properties_of_co... and http://www.academicjournals.org/article/article1380626432_Varkey.pdf http://www.academicjournals.org/article/article1380626432_Va... I wish hospitals, airports, and other shared spaces would use brass hardware or other alternatives rather than steel, particularly on door knobs and other highly trafficked surfaces. I always wondered if there'd be a market for selling such biocidal and viricidal hardware, either passive hardware using special alloys or surfaces (e.g. untreated wood performs well by locking pathogens in pores so they don't transfer readily); or active hardware that, e.g., ran a small current across the surface.
- two2two 8y ago
  They found the plastic trays to be the worst. > Of the surfaces tested, plastic security screening trays appeared to pose the highest potential risk, and handling these is almost inevitable for all embarking passengers.
  - myself248 8y ago
    I've wondered how athelete's foot fungus feels about the remove-your-shoes regulations. What a boon to reproduction!
    - wahern 8y ago
      I hope it works similar to bacteria, where "tile, wood, and laminate surfaces transfer much more bacteria than carpeted surfaces." (https://news.nationalgeographic.com/news/2014/03/140315-five-second-rule-bacteria-food-safety/ https://news.nationalgeographic.com/news/2014/03/140315-five...) Most of the security areas I've seen are carpeted, albeit low pile carpeting. But maybe it doesn't work the same; or maybe it's just so contaminated it doesn't matter. The best solution[1], though, is probably to sell your soul to the devil and enroll in TSA Precheck. [1] Presuming there's a real problem. Aren't the fungi that cause atheletes foot (tinea pedis) and onychomycosis (infection of the nail bed) pretty much everywhere already? I think it's more a matter of keeping your [low-temperature] extremities dry. Onychomycosis is almost inevitable past a certain age because of immune and circulatory deficiencies.
- 21 8y ago
  I'm pretty sure wood is terrible for this purpose. Note how in hospitals wood is nonexistent.
  - anateus 8y ago
    It may be absent, but tests on food prep surfaces show wood performs surprisingly well. Better than plastic.
    - lmkg 8y ago
      From what I remember, wood's main difference is that is absorbs water. On the one hand, this wicks water away from the surface making it dryer immediately (bad for pathogens), but on the other hand it retains moisture for longer (good for pathogens). These trade-offs are overall beneficial for the use case of a cutting board, but that may be a very narrow set of conditions. This is aside from the fact that hospitals are a more adversarial environment than kitchens--every sneeze might contain ebola, and every patient might be immunocomprimised. I would imagine airports fall somewhere in the middle.
  - wahern 8y ago
    Plastic and steel are common because they're easy to clean reliably. The problem is that the properties that make them easy to clean--smooth, inert--are the same properties that allow pathogens to linger. Microsurfaces on, e.g., hardwood have properties that sequester and kill pathogens. (https://news.ncsu.edu/2014/09/cutting-boards-food-safety/ https://news.ncsu.edu/2014/09/cutting-boards-food-safety/) However, that can also make them more difficult to clean, particularly in a commercial or industrial setting where the process needs to be low-cost, minimally labor intensive, scaleable, and reliable. Similarly, the surface properties may be difficult to maintain or restore. For example, perhaps oil build up on wood surfaces regularly touched by passers-by reduces or eliminates the antimicrobial qualities, or even make it worse than the alternatives. That's the rub--how to design (and market) cheap hardware that is easy to maintain while maximizing antiseptic properties during use. We've optimized for the former (cheap, easy, reliable sanitation) but neglected to appreciate that actual cleanliness sucks because typical materials in high-traffic areas go from pristine to cesspools almost immediately and, crucially, stay that way until the next round of cleaning briefly sanitizes the surface.
- sethbannon 8y ago
  Unfortunately this feels like situation where the free market will fail to incentivize the best solution. The airport itself does not feel the economic pain from its travelers getting sick from touching its steel surfaces. The passengers likely aren't even aware this choice might have caused their sickness. So airports will always choose steel over copper/silver/brass so long as steel is cheaper. This seems like a reasonable place for regulators to step in.
  - stretchwithme 8y ago
    I agree. And perhaps a subsidy. The potential avoidance of misery justifies making it easy to choose.
    - AmericanChopper 8y ago
      A regulation and a subsidy are called for because people don't wash their hands often enough?
      - myself248 8y ago
        Or aren't able to. Airports are a controlled environment where your free will is a lot less meaningful than usual. I'm quite fond of hand-washing, and I hate airports because they make it so difficult. You have to touch everything, and everything touches you, and sinks are few and far between, and only located in jam-packed restrooms. You also can't bring decent quantities of hand sanitizer through checkpoints. This ban on liquids and gels applies to alcohol gel, BZK foam, povidone solution, and towelettes premoistened with any of the above. I checked. Once aboard the plane, there's no effective handwashing. The bathrooms are so small you brush the walls with your shoulders while turning around, the trash-flap has to be shoved on to deposit your paper towel, and the door latch has to be touched to be operated. After you've arrived at your destination, luggage at the baggage claim has been handled by folks outside your control, who themselves probably don't wash their hands very often, and once you've grabbed it, even if you wipe it down with some towelettes you've squirreled away, there's no restroom nearby to wash the remaining mostly-dead germs off your hands. So please, tell me which airports you've been flying where handwashing is easy, and I'll try to schedule a connection through one to check it out.
- Fomite 8y ago
  There's a huge number of companies already in this space - the biggest problem is actually showing that they work, rather than just being somewhat nifty materials that work in a lab. For example, a recent RCT showed that antibacterial-impregnanted scrubs were relatively ineffective in hospitals: https://www.cambridge.org/core/journals/infection-control-and-hospital-epidemiology/article/antimicrobial-scrub-contamination-and-transmission-ascot-trial-a-threearm-blinded-randomized-controlled-trial-with-crossover-design-to-determine-the-efficacy-of-antimicrobialimpregnated-scrubs-in-preventing-healthcare-provider-contamination/CC3DAA1132619E835EC2BABA9F0C7686 https://www.cambridge.org/core/journals/infection-control-an...
- agumonkey 8y ago
  there are documentaries about that, and at least one hospital was shown using copper handles and knobs in some area.
Symmetry 8y ago
A good reason to wash your hands frequently.
- samstave 8y ago
  I wonder if there were UV hand "washers" all over the place if that would help. If they had the UV hand driers in the restrooms as well as UV baths around the entrances to the xray scanners, such that everyones plastic tub that entered the xray machine was also UV'd as it went through... (Although I dont know how long it would have to be under UV to impact....)
  - Fomite 8y ago
    So there are UV devices used to help disinfect rooms, and there's a lot of time needed for killing. And then there's the whole cancer downside...
  - namibj 8y ago
    You should be able to cut the UV time down to a second or two, before you get problems with the stuff starting to melt from the radiative heat, even if you use a strong fan to cool the surface. This is worst-case, and I do think you can get away without a fan, but there might be edge cases.
21 8y ago
One interesting thing I've read, is that frequent disinfection (like in hospitals) actually increases the prevalence of highly resistant strains. One reason is obvious - those better adapted survive and pass on resistence genes. But the second reason is more interesting - the disinfection will kill the lesser resistant bacterias, so the resistent ones have less competition to worry about, thus they can concentrate their evolution efforts towards resisting the disinfection. Each extra gene a bacteria carries has big costs on it's fitness, so removing the competition increases the available budget for resistance genes. I know the article is about viruses, I don't know if viruses compete between themselves in the environment.
- patejam 8y ago
  What about just cleaning? i.e. wiping down with non-antibacterial soap. I know viruses are not bacteria, so I'm a bit off topic, but still interested.
  - Fomite 8y ago
    Cleaning removes things pretty uniformly, but also doesn't result in a sterile (or even really quasi-sterile) surface. Disinfection is a pretty important next step after cleaning.
    - namibj 8y ago
      There are ways to clean that are so effective that even endospores will be removed, though strong oxidative disinfectants seem to generally be more effective. Something like strong UV-C irradiation or a wash with ethylene oxide should result in the destruction of all life remaining on a washed surface.
      - Fomite 8y ago
        UV-C irradiation generally falls under "disinfection" because if you haven't cleaned the surface of gross contaminants first, it doesn't work very well.
leptoniscool 8y ago
There should be more hand sanitizer dispenses in these places
- AWildC182 8y ago
  I've kinda suspected this for a while so I generally make a point of going to the nearest bathroom and washing my hands after getting through security, especially if I'm eating something before boarding.
  - myself248 8y ago
    Yup, and I've developed some pretty effective habits of unwrapping other food in the style of a banana, so my hands touch only the wrapper, and advance/expose the food so it's touched only with my mouth. Treat everything like a push-pop, basically.
    - deleted 8y ago
      [deleted]
ptero 8y ago
I might have missed it, but I do not know if they tested for significant quantities instead of just presence. A presence of all sorts of pathogens is pretty common everywhere (you can find all sorts of stuff under kids nails), it is the concentration above certain thresholds that significantly increases disease risk. I would be interested in how concentrations of different pathogens compare between, say an airport, supermarket and hospital ER reception. My 2c.
notacoward 8y ago
Those plastic bins at security were apparently the worst. I go through airports quite a bit, but never really thought about that particular vector. It's especially bad because the very first thing a lot of people do after security is find some food. Instead, it would be a good idea to find a restroom and wash your hands, then find food.
- Fomite 8y ago
  From an epidemiological standpoint, you should always find a washroom and wash your hands before eating, pretty much regardless of setting.
  - notacoward 8y ago
    True, and I'm sure you'll say you do that, but the fact is that most people are more selective. It's useful to know when it's particularly critical.
    - Fomite 8y ago
      I'm just saying - the phrase "fecal patina" gets used a lot in my field...
      - notacoward 8y ago
        I'm going to start using that phrase to describe some of the software I work with. Maybe it'll catch on. Having recently been through a real live measles-containment exercise (don't ask) I've gained a much greater appreciation of what epidemiologists and other public-health professionals do. People just don't realize how they're being protected every day. I hope some of your colleagues are talking to TSA and airport management about these findings.
        Fomite 8y ago
        Some of us are distracted by the quarantined Emirates flight, but yeah, this has been met with considerable interest.

50 points by uptown 8y ago

Steel is one of the worst surfaces when it comes to harboring pathogens. AFAIU silver and copper are the best. Brass and bronze come in a distant 2nd (in absolute terms) but still significantly better than steel, where pathogens linger subject only to the external environment. See, e.g. https://en.wikipedia.org/wiki/Oligodynamic_effect https://en.wikipedia.org/wiki/Oligodynamic_effect and https://en.wikipedia.org/wiki/Antimicrobial_properties_of_copper https://en.wikipedia.org/wiki/Antimicrobial_properties_of_co... and http://www.academicjournals.org/article/article1380626432_Varkey.pdf http://www.academicjournals.org/article/article1380626432_Va... I wish hospitals, airports, and other shared spaces would use brass hardware or other alternatives rather than steel, particularly on door knobs and other highly trafficked surfaces. I always wondered if there'd be a market for selling such biocidal and viricidal hardware, either passive hardware using special alloys or surfaces (e.g. untreated wood performs well by locking pathogens in pores so they don't transfer readily); or active hardware that, e.g., ran a small current across the surface.

two2two 8y ago
They found the plastic trays to be the worst. > Of the surfaces tested, plastic security screening trays appeared to pose the highest potential risk, and handling these is almost inevitable for all embarking passengers.
- myself248 8y ago
  I've wondered how athelete's foot fungus feels about the remove-your-shoes regulations. What a boon to reproduction!
  - wahern 8y ago
    I hope it works similar to bacteria, where "tile, wood, and laminate surfaces transfer much more bacteria than carpeted surfaces." (https://news.nationalgeographic.com/news/2014/03/140315-five-second-rule-bacteria-food-safety/ https://news.nationalgeographic.com/news/2014/03/140315-five...) Most of the security areas I've seen are carpeted, albeit low pile carpeting. But maybe it doesn't work the same; or maybe it's just so contaminated it doesn't matter. The best solution[1], though, is probably to sell your soul to the devil and enroll in TSA Precheck. [1] Presuming there's a real problem. Aren't the fungi that cause atheletes foot (tinea pedis) and onychomycosis (infection of the nail bed) pretty much everywhere already? I think it's more a matter of keeping your [low-temperature] extremities dry. Onychomycosis is almost inevitable past a certain age because of immune and circulatory deficiencies.
21 8y ago
I'm pretty sure wood is terrible for this purpose. Note how in hospitals wood is nonexistent.
- anateus 8y ago
  It may be absent, but tests on food prep surfaces show wood performs surprisingly well. Better than plastic.
  - lmkg 8y ago
    From what I remember, wood's main difference is that is absorbs water. On the one hand, this wicks water away from the surface making it dryer immediately (bad for pathogens), but on the other hand it retains moisture for longer (good for pathogens). These trade-offs are overall beneficial for the use case of a cutting board, but that may be a very narrow set of conditions. This is aside from the fact that hospitals are a more adversarial environment than kitchens--every sneeze might contain ebola, and every patient might be immunocomprimised. I would imagine airports fall somewhere in the middle.
- wahern 8y ago
  Plastic and steel are common because they're easy to clean reliably. The problem is that the properties that make them easy to clean--smooth, inert--are the same properties that allow pathogens to linger. Microsurfaces on, e.g., hardwood have properties that sequester and kill pathogens. (https://news.ncsu.edu/2014/09/cutting-boards-food-safety/ https://news.ncsu.edu/2014/09/cutting-boards-food-safety/) However, that can also make them more difficult to clean, particularly in a commercial or industrial setting where the process needs to be low-cost, minimally labor intensive, scaleable, and reliable. Similarly, the surface properties may be difficult to maintain or restore. For example, perhaps oil build up on wood surfaces regularly touched by passers-by reduces or eliminates the antimicrobial qualities, or even make it worse than the alternatives. That's the rub--how to design (and market) cheap hardware that is easy to maintain while maximizing antiseptic properties during use. We've optimized for the former (cheap, easy, reliable sanitation) but neglected to appreciate that actual cleanliness sucks because typical materials in high-traffic areas go from pristine to cesspools almost immediately and, crucially, stay that way until the next round of cleaning briefly sanitizes the surface.
sethbannon 8y ago
Unfortunately this feels like situation where the free market will fail to incentivize the best solution. The airport itself does not feel the economic pain from its travelers getting sick from touching its steel surfaces. The passengers likely aren't even aware this choice might have caused their sickness. So airports will always choose steel over copper/silver/brass so long as steel is cheaper. This seems like a reasonable place for regulators to step in.
- stretchwithme 8y ago
  I agree. And perhaps a subsidy. The potential avoidance of misery justifies making it easy to choose.
  - AmericanChopper 8y ago
    A regulation and a subsidy are called for because people don't wash their hands often enough?
    - myself248 8y ago
      Or aren't able to. Airports are a controlled environment where your free will is a lot less meaningful than usual. I'm quite fond of hand-washing, and I hate airports because they make it so difficult. You have to touch everything, and everything touches you, and sinks are few and far between, and only located in jam-packed restrooms. You also can't bring decent quantities of hand sanitizer through checkpoints. This ban on liquids and gels applies to alcohol gel, BZK foam, povidone solution, and towelettes premoistened with any of the above. I checked. Once aboard the plane, there's no effective handwashing. The bathrooms are so small you brush the walls with your shoulders while turning around, the trash-flap has to be shoved on to deposit your paper towel, and the door latch has to be touched to be operated. After you've arrived at your destination, luggage at the baggage claim has been handled by folks outside your control, who themselves probably don't wash their hands very often, and once you've grabbed it, even if you wipe it down with some towelettes you've squirreled away, there's no restroom nearby to wash the remaining mostly-dead germs off your hands. So please, tell me which airports you've been flying where handwashing is easy, and I'll try to schedule a connection through one to check it out.
Fomite 8y ago
There's a huge number of companies already in this space - the biggest problem is actually showing that they work, rather than just being somewhat nifty materials that work in a lab. For example, a recent RCT showed that antibacterial-impregnanted scrubs were relatively ineffective in hospitals: https://www.cambridge.org/core/journals/infection-control-and-hospital-epidemiology/article/antimicrobial-scrub-contamination-and-transmission-ascot-trial-a-threearm-blinded-randomized-controlled-trial-with-crossover-design-to-determine-the-efficacy-of-antimicrobialimpregnated-scrubs-in-preventing-healthcare-provider-contamination/CC3DAA1132619E835EC2BABA9F0C7686 https://www.cambridge.org/core/journals/infection-control-an...
agumonkey 8y ago
there are documentaries about that, and at least one hospital was shown using copper handles and knobs in some area.

Symmetry 8y ago

A good reason to wash your hands frequently.

samstave 8y ago
I wonder if there were UV hand "washers" all over the place if that would help. If they had the UV hand driers in the restrooms as well as UV baths around the entrances to the xray scanners, such that everyones plastic tub that entered the xray machine was also UV'd as it went through... (Although I dont know how long it would have to be under UV to impact....)
- Fomite 8y ago
  So there are UV devices used to help disinfect rooms, and there's a lot of time needed for killing. And then there's the whole cancer downside...
- namibj 8y ago
  You should be able to cut the UV time down to a second or two, before you get problems with the stuff starting to melt from the radiative heat, even if you use a strong fan to cool the surface. This is worst-case, and I do think you can get away without a fan, but there might be edge cases.

21 8y ago

One interesting thing I've read, is that frequent disinfection (like in hospitals) actually increases the prevalence of highly resistant strains. One reason is obvious - those better adapted survive and pass on resistence genes. But the second reason is more interesting - the disinfection will kill the lesser resistant bacterias, so the resistent ones have less competition to worry about, thus they can concentrate their evolution efforts towards resisting the disinfection. Each extra gene a bacteria carries has big costs on it's fitness, so removing the competition increases the available budget for resistance genes. I know the article is about viruses, I don't know if viruses compete between themselves in the environment.

patejam 8y ago
What about just cleaning? i.e. wiping down with non-antibacterial soap. I know viruses are not bacteria, so I'm a bit off topic, but still interested.
- Fomite 8y ago
  Cleaning removes things pretty uniformly, but also doesn't result in a sterile (or even really quasi-sterile) surface. Disinfection is a pretty important next step after cleaning.
  - namibj 8y ago
    There are ways to clean that are so effective that even endospores will be removed, though strong oxidative disinfectants seem to generally be more effective. Something like strong UV-C irradiation or a wash with ethylene oxide should result in the destruction of all life remaining on a washed surface.
    - Fomite 8y ago
      UV-C irradiation generally falls under "disinfection" because if you haven't cleaned the surface of gross contaminants first, it doesn't work very well.

leptoniscool 8y ago

There should be more hand sanitizer dispenses in these places

AWildC182 8y ago
I've kinda suspected this for a while so I generally make a point of going to the nearest bathroom and washing my hands after getting through security, especially if I'm eating something before boarding.
- myself248 8y ago
  Yup, and I've developed some pretty effective habits of unwrapping other food in the style of a banana, so my hands touch only the wrapper, and advance/expose the food so it's touched only with my mouth. Treat everything like a push-pop, basically.
  - deleted 8y ago
    [deleted]

ptero 8y ago

I might have missed it, but I do not know if they tested for significant quantities instead of just presence. A presence of all sorts of pathogens is pretty common everywhere (you can find all sorts of stuff under kids nails), it is the concentration above certain thresholds that significantly increases disease risk. I would be interested in how concentrations of different pathogens compare between, say an airport, supermarket and hospital ER reception. My 2c.

notacoward 8y ago

Those plastic bins at security were apparently the worst. I go through airports quite a bit, but never really thought about that particular vector. It's especially bad because the very first thing a lot of people do after security is find some food. Instead, it would be a good idea to find a restroom and wash your hands, then find food.

Fomite 8y ago
From an epidemiological standpoint, you should always find a washroom and wash your hands before eating, pretty much regardless of setting.
- notacoward 8y ago
  True, and I'm sure you'll say you do that, but the fact is that most people are more selective. It's useful to know when it's particularly critical.
  - Fomite 8y ago
    I'm just saying - the phrase "fecal patina" gets used a lot in my field...
    - notacoward 8y ago
      I'm going to start using that phrase to describe some of the software I work with. Maybe it'll catch on. Having recently been through a real live measles-containment exercise (don't ask) I've gained a much greater appreciation of what epidemiologists and other public-health professionals do. People just don't realize how they're being protected every day. I hope some of your colleagues are talking to TSA and airport management about these findings.
      - Fomite 8y ago
        Some of us are distracted by the quarantined Emirates flight, but yeah, this has been met with considerable interest.