Hacker News Reader

Comment by xiii1408 | Hacker News Reader

This has been well-known by swimmers for a long time: chlorine itself is pretty much fine for you. It's the chemical reaction of chlorine with waste products, including human waste, that produces toxic byproducts and the concomitant "pool smell."

If you swim in a well-maintained pool (e.g. one of my university's competition swimming pools), there's no "pool smell."

View on HN

> chlorine itself is pretty much fine for you

It's difficult to imagine a context that would make this sentence reasonable. Chlorine is a light halogen. It's fine if it's bound to something stable, like in salt. It certainly isn't fine by itself. It's literally one step up from fluorine, the most horrifying substance known to man.

The safety diamond for chlorine rates it a 4 for health: "Very short exposure could cause death or major residual injury".

Not to mention the fact that elemental Chlorine gas is incredibly poisonous and was used in WW1 (the first gaseous chemical weapon according to Wikipedia).

One step from being fluorine? That's a nuclear reaction. Elements can't change during chemical reactions.

Not one reaction step, one row up in the periodic table, as a sign for "what is it chemically similar to"

The scent of bleach and the scent of "pool smell" are almost exactly the same to me.

That is because both are the same thing: sodium hypochlorite

strangemonad elsewhere here posted a link to a video evaluating the question of how much pee there is in pools, using the excretion of an artificial sweetener - which is only in urine and not, like urea, also in sweat - as the indicator.

The presenter is also dubious about the origin of the smell, and thinks that it comes from the chlorine, not the trichloramine product of chlorine interacting with urea. So he tests it out by mixing pool chlorine into two buckets, putting urine in one of them, covering for a few days, and smelling.

That experiment is run starting at https://youtu.be/S32y9aYEzzo?t=284 . The chlorinated water, even at 4x concentration, "smells just like water." While the one where urine was added "smells like a pool."

is it possible that this is simply sweat instead of actual pee?

serious question - I thought sweat is mostly comprised of the same excretion. just surprised 'peeing in the pool' is so normal.

The video covers that question.

The description of the details start at https://youtu.be/S32y9aYEzzo?t=88 . The "show more" for the video has a link to the researcher's paper at Dropbox. You can also read the paper at https://pubs.acs.org/doi/full/10.1021/acs.estlett.7b00043 .

The relevant text from in the ACS link "ACE, used in prepackaged foods,(18, 29, 30) is not metabolized by humans; it is completely absorbed and excreted exclusively in the urine,(29, 31)"

[29] Voltz, M.; Christ, O.; Eckert, H. G.; Herok, J.; Kellner, H.-M.; Rupp, W. Kinetics and biotransformation of acesulfame K. In Acesulfame-K; Mayer, D. G.; Kemper, F. H., Eds.; Marcel Dekker: New York, 1991; pp 7– 26.

[31] Renwick, A. G. The metabolism of intense sweeteners Xenobiotica 1986, 16, 1057– 71 DOI: 10.3109/00498258609038983

Any idea what makes tap water smell like a pool? It evaporates out pretty quickly (a day or so in a normal pitcher), whatever the cause, and I've always assumed it was chlorine since it smells like a tiny waft of bleach.

Quoting myself in the comment you replied to, "the trichloramine product of chlorine interacting with urea".

That's probably less of an issue for water straight from the tap than a pool / a bucket of water that was peed into. Unless there's more urea in tap water than I expect.

Are you sure your University isn't using bromine instead of chlorine? Bromine is more expensive but then you don't get the "pool smell". It's what they use at Disney parks.

You do get that boron smell though. Kinda dirty smelling.

I think you're thinking of bromine, not boron.

Yes. Thanks.

A well-maintained & chemically balanced pool should not smell under typical circumstances.

I owned a 40,000 gallon in-ground pool and followed a method called the "Trouble-Free Pool method". The only chemical requirements are normal bleach (chlorine) and a pH adjuster. No "shock", no algaecide, no pool store shenanigans. My pool was pristine & sparkling blue, and never smelled or hurt guests' eyes or turned blonde hair green. My family (including two small children) could swim all day long and never have irritated eyes.

It's really about being very careful about the chemistry (step 1 is to get a high-quality testing kit). Public pools are... less than fastidious about chemical balance and standards are much looser.

> chlorine itself is pretty much fine for you.

That's...not why it was used in warfare.

Reply on news.ycombinator.com