Science Questions

Would filtering farts prevent hospital acquired infections?

Sun, 29th Jan 2012

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John Miranda asked:



Excellent interview on farts.


If all the assholes in a hospital had effective fart-gas filters (that is ALL the patients and all the staff - I know, good luck on the staff side,) what would the reduction in Hospital Acquired Infections be? I understand all the airborne bacteria spread in all kinds of ways through the HVAC system, butt, as you know, HAI is a serious problem. Therefore, I believe I am asking a serious question, although it appears little real scientific research has been done on this subject.


John M. Miranda


Chris - This is a question that we answered a few years ago and Ben Valsler went to see Simon Park in Surry who actually did the experiment for us and weve got the bit of audio from 4 years ago in 2008 where they actually did the experiment to see how efficiently farts can spread potential pathogens.

Ben -  We know that coughs and sneezes can spread diseases and that's how many respiratory infections actually get transferred, but you were thinking there might be another way that bacteria could be transmitted.

Simon -  Yes.  I have two sons, Joe and Josh and they've developed a sort of obsession with this homemade biological prank of farting and I thought, why do we find this so offensive and why is it dangerous, and can I demonstrate this to my children to stop them doing it? 

So I thought of some experiments where I could actually prove whether or not farts could transmit bacteria.  So, what I've done is taken some agar plates that are very good at culturing faecal bacteria and done some very crude experiments where weve exposed the plates to people farting in terms of a naked fart with no pants and no jeans on, and also, people farting with underpants and jeans on.

Ben -  So you've set this up by passing wind shall we say, on what's called a MacConkeys agar plate.  One of them clearly has some colonies on and the other one looks completely clean.  So Simon, which one is which?

Simon -  The plate that's totally clean is one that was exposed with pants and jeans on, so its obviously the pants and jeans are being very effective at filtering out any faecal bacteria, but the plate that was exposed to the naked emission has a splattering of red colonies on it and they are very indicative of E. coli thats a very common faecal bacteria.  That's a good indicator of faecal contamination.  There's such huge numbers of bacteria in a stool that its inevitable that we will transmit bacteria after flatulence.

Chris -  So the bottom line is if you excuse that pun if you cover the area, as someone hopefully in hospital staff and patients would be expected to be, then the infectious transmission risk is probably extremely low.  If you go around flatulating on people in hospital without the rear uncovered, there is a likelihood you may expel some organisms that could make people unwell. 


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I missed the reference.
However, while some bacteria may become airborne through flatulence, the majority of the human pathogens are transmitted either through coughing/sneezing, or through handling stuff, and eventually bringing the material from the hands to the mouth.

A good air filtration system might help with the farts, as you put it, as well as airborne diseases from coughing.

Contact spreading of diseases can be reduced by washing hands regularly, especially when going between patient rooms. CliffordK, Sun, 29th Jan 2012

Stone the crows, what hospital have you been visiting?

I rather doubt it do anything much to prevent the spread of bacteria, but it might make the atmosphere a tad fresher. Don_1, Mon, 30th Jan 2012 RD, Mon, 30th Jan 2012

We did this experiment on the Naked Scientists show in May 2008 with the help of microbiologist Simon Park, from Surrey.

Pictures of the farted-on culture plates are included with the above...

Chris chris, Mon, 30th Jan 2012

Thanks for the link.

So...  the hospital gowns that are rather revealing..  may not in fact be very protective 

It is interesting that clothes were quite protective.  You didn't mention the experimental protocol.  Was the petri dish just nearby in the room....  or positioned where it might in fact get direct splatter?

One thing to keep in mind.  Bugs that infect the gut often aren't too pathogenic in the lungs.  So, the biggest risk (if there is any) would be passing gas in a cafeteria, where the bugs might be able to settle on food. CliffordK, Mon, 30th Jan 2012

It's not entirely true that gut bugs are generally apathogenic in the respiratory tract. Ventilated patients often succumb to E. coli infections, and Steps and Pseudomonads, as well as fungi (like candida), can also cause a problem.

Chris chris, Tue, 31st Jan 2012

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