Toilets spew invisible aerosol plumes with every flush | Hacker News Reader

Toilets spew invisible aerosol plumes with every flush

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34 pointsnabla918 comments

The human body is near 37C / 99F and ambient room temperature is typically kept near 22 C / 70 F. Humans are constantly shedding skin dust, which due to their higher temperature are always floating around rooms. Additionally, people are constantly spreading tiny aerosolized particles from their lungs, even without coughing, simply by talking and breathing. For example:

https://www.science.org/doi/10.1126/science.abd9149

"Airborne transmission of respiratory viruses" (2021) Science

> "Advances in aerosol measurement techniques, such as aerodynamic and scanning mobility particle sizing, have shown that the majority of exhaled aerosols are smaller than 5 μm, and a large fraction are <1 μm for most respiratory activities, including those produced during breathing, talking, and coughing."

Such droplets can likely pass through cloth masks with little difficulty, and 6 feet of distance is probably irrelevant. The only thing that prevents transmission and infection between nearby people is containment efforts such as BSL-3/4 laboratory precautions and even there, accidental transmission has been documented.

Without highly strict quarantine and isolation protocols, we're really all just swimming in the same petri dish when it comes to respiratory transmission.

> people are constantly spreading tiny aerosolized particles from their lungs

Which (for me) brings up this never-asked question. You hear about the cattle methane ... but how much CO2 do 8 billion people breathe out in a year?

You are simply breathing out CO2 that is already in the air, what you might want to point at instead is people farting.

reminds me of this article (posted a few times): https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...

you missed a great deal of opportunity telling people they are wrong

No.

People breathe out CO2 that is product of their own metabolism.

Oxygen + carbohydrates in, CO2 out.

Eventually I found an article that addresses this question:

https://www.nrdc.org/stories/do-we-exhale-carbon

It calculates that "a population of 7 billion people, breathing away for 365.25 days per year, and you get an annual CO2 output of 2.94 billion tons." It then points out that " human respiration is part of a “closed loop cycle” in which our carbon dioxide output is matched by the carbon dioxide taken in by the wheat, corn, celery, and Ugli fruit that we eat." Except, of course, for weight we add to our bodies.

Of course that doesn't stop each of us from combusting 5 tons of CO2 each year.

Two older and interesting studies:

Urine streams aerosolize bacteria present in the toilet; sitting understandably causes more exposure than standing. A custom foam covering the interior surfaces is effective at negating the splash effect (though it presumably needs reapplication after a flush). https://aricjournal.biomedcentral.com/articles/10.1186/s1375...

A recent literature review https://ami-journals.onlinelibrary.wiley.com/doi/10.1111/jam...

This mentions a paper by Yahya 1992 https://www.jstor.org/stable/44535384 which examines use of surfactants (soaps) in flush water, and finds them to be effective. Seems to be more useful than disinfectants like chlorine.

My plumber has been saying this for decades.

I always assumed this is why the lid on the toilets exists.

I have seen many arguing about leaving the toilet seat up and down but I always felt the only real answer is to put the whole lid down.

Even if you’re not flushing the water still evaporates and brings some tiny particles with it.

FTA: A typical commercial toilet generates a strong upward jet of air with velocities exceeding 6.6 feet per second (2 meters per second), rapidly carrying these particles up to 5 feet (1.5 meters) above the bowl within eight seconds of the start of the flush."

There are any number of sodium hypochorite disinfectants on the market with a narrow nozzle for squirting a stream of it into the bowl.

From what I gather practices vary, some squirt the bleach into the bowl after flushing and some beforehand.

Question: whilst neither practice would stop the aerosols from forming what would the likely effect of the hypochlorite be on bacterial/viral load in said aerosols if squirted in before flushing?

Hypochlorite is a highly efficient disinfectant so presumably its effectiveness in this situation would depend on its concentration and the degree of its mixing.

Has any study of this kind been undertaken? (With the large number of bathroom bleach products on the market surely someone has done such a study.)

2017: https://ihpi.umich.edu/news/your-cell-phone-10-times-dirtier...

> One of the worst places to use your phone is in the bathroom, Martin and Whittier both agree. When toilets flush, they spread germs everywhere, which is how phones end up with fecal bacteria like E. coli. “Taking a cell phone into the bathroom and then leaving with it is kind of like going in, not washing your hands and then coming back out," Martin says. "It’s the same level of concern."

If your nose works you can detect this in public restrooms. When I travel I prefer to use aircraft lavs with strong negative pressure on every flush.

What you’re smelling in a public restroom might well be other products though — the urea and VOCs in the urine, and the byproducts of bacteria feeding on the urine — so it isn’t really an indication of what is in the bowl. And on a longer flight, those bathrooms might have been used by 100 people before you, likely far more than a ground side bathroom with regular cleaning crew visits.

> When I travel I prefer to use aircraft lavs with strong negative pressure on every flush.

A round trip plane ride for each toilet break seems expensive and time consuming!

Ok, so we are all covered with poo water. Now what?

Besides washing your hands you could also wash your face.

Any different than the plumes people spew multiple times a day, apart from the water content? I'd expect the pathogen content to be the same (where do they come from? Hmmm)

Where I live we wear pants.

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