cause of red eye

Jump to latest Follow Reply
E

edavis6678

0
May 20, 2014
17
Southern California
So i got into a friendly debate with my father-in-law last night, (the guy that seems to be an expert of everything), about a statement he made yesterday that suddenly science has discovered the cause of "red eye" in pools was people peeing in it.

Later I googled and apparently the National Swimming Pool Fondation (National Swimming Pool Foundation | News > Healthy Pools Red Eye
) had a press release about pool safety and it seemed that a number of news organizations twisted the story to imply that "Pee is the single cause of Red eye".

Pee, not chlorine, causes red eyes from swimming pools: CDC - Trending - CBC News

CDC: Blame It On The Pee If Your Eyes Are Red After Swimming CBS San Francisco

I then tried to explain how Chlorine reacts with bacteria which forms Chloramines which is that "smell" you get from a pool. This can come from "pee", but really any bacteria (dead bugs, leaves, etc..). Later we got into a debate of my chemistry credentials and then I decided to come here to help support the facts.

First, I thought it was PH imbalance that was the major factor with people having "stinging" or "red" eyes -- not the presence of bacteria. So, if red-eye is not caused by this, Is it actually Chloramines that cause red eye or the bacteria?
 
CC can cause red and burning eyes. CC can come from pee to dead algae to bugs. If there are CC's in the water, they can an will irritate the skin and eyes.
 
Combined Chloramines cause red eyes and also pH out of range can cause it.
As well as these, also osmotic pressure on the eyeball can cause them to turn red.

The Headline that pee causes red eyes is an attention grabber. Within the article itsef as aquoted " "It's not what you think. What you smell are actually chemicals that form when chlorine mixes with ...."

The chemicals that form ARE Combined Chloramines and they cause red eyes.

Unfortunately, there are too many people who read, but do not comprehend what it is they are reading.
 
Nothing new. Chloramines are probably the chief cause of red eyes.... and peeing in the pool is probably the number one cause of that. That is probably an oversimplification, but the notion does hold some truth.

From a global perspective, we keep our pools too basic and maybe that causes some red eye. Addition of slat is another thing that can prevent red eye. There isn't one single "answer" to the question.

Let the old guy win one.... you will be the beneficiary!
 
Last edited:
See this paper which describes the conditions and causes of eye irritation in swimming pools. The primary cause is when one keeps their eyes open under water that is lower in salt level because osmotic pressure builds up in the eyes causing them to hurt and get irritated. The salt level of human tears and eye fluids is around 8000 ppm but the study found that at 7000 ppm all eye irritation stopped even with 2 ppm FC (and no CYA) while with no chlorine there was no irritation at or above 5000 ppm. Note that saltwater chlorine generator pools in the U.S. typically have salt levels of around 3000 ppm.

Some subjects had eye irritation at 1 ppm FC, but again this is with no CYA in the water and also no salt. At all salt levels, monochloramine was more irritating than chlorine.

The paper also showed that pH was not a large factor for eye irritation at least in the range of 7 to 9 in pH, but that chloramines, specifically testing monochloramine, did cause irritation if at higher levels especially when the salt level was lower (i.e. the various factors combine somewhat additively).

Ammonia in sweat and urine combines with chlorine very quickly to form monochloramine. See this post for the nitrogenous content of sweat and urine. Note that there is even more urea than ammonia. Chlorine oxidizes urea more slowly and when it does so it also produces very volatile and irritating nitrogen trichloride. This is much more of an issue in commercial/public pools due to their high bather load and also because some of these pools do not use CYA so the active chlorine level is higher as well (that tends to produce even more nitrogen trichloride).

Your father is mostly right in the sense that most of the chloramines in swimming pools come from bather load, but it's not because people are peeing in the pool (though that obviously makes things worse if they do). If you had a large dump of organics into the pool such as from pollen, then some chloramines could be formed but they generally stay stuck to such pollen whereas sweat and urine contain more chemicals that are soluble in water. Eventually though, if you had organic material in water (including leaves) the cells would break down enough so that their contents would be released and then you'd have a situation closer to bather load with sweat and urine, but again in commercial/public pools the largest introduction of nitrogenous organics and ammonia into the water is from bathers.

The CDC report is not new science. This has been known for decades. The CDC every few years comes out and basically tells people not to pee in the pool. So it's more of a reminder cloaked in a "science report" than anything else.
 
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply