Pool chemical intolerance

Happy new year to all our swimming pool group followers, so that we don’t all get bored before spring opening time I hope to post some information that I hope will be useful to know and debate. This first post for 2014 is in response to Mike Kearney’s comments on another thread on SFN.

“I have been a lifelong recreational swimmer, despite having an intolerance of pool treatment chemicals. We are soon to get a new pool, which I hope will have Ozone or UV treatment. For me, swimming is the perfect way of taking exercise - lying down in a state of weightlessness! Is there a swimming pool thread? I will look for it”.

Well that’s a good opener for a discussion.

Before I got involved in the swimming pool industry I spent a lot of time researching different forms of water sanitising, after all we all know chlorine is bad for us/gives you cancer/asthma etc.

I spoke to many eminent people in the pool industry and quite a wide opinion on different types and of ways of keeping your pool safe and more importantly sanitary.

Swimming pool chemical intolerance is something a lot of people have endured. When I was at school many years ago, the weekly trip to the local pool for swimming lessons was always something we looked forward to and you knew you were getting close to the pool because your nose gave you an early indication. In fact about ¼ of a mile before you reached the pool building it was possible to smell the pool. Thankfully those days are gone because we now know a lot more of the nature of the chemicals used to disinfect our pools.

Chlorine gets a very bad rap in the press, it’s a very easy target to scare people with but chlorine does a huge job of keeping us safe for the majority of the time. Chlorine doesn’t actually have much of a smell to it, if you sniff a bottle of pool chlorine the smell is quite weak until it reacts with something, put a little on your skin and you can smell it all day long. That isn’t actually the chlorine you can smell it is the by-products of the disinfection process or (disinfection by-products DPB’s). These range from nitrogen trichloride, cyanogen chloride and chloroform, otherwise known as trihalomethanes (THM’s) The pungent smell of “swimming pool” is caused by the nitrogen trichloride but if you are swimming in an indoor pool they may well use ultra violet light (UV) to reduce the organic chloramines but in doing so the nitrogen is converted to nitrate and that is responsible for reducing the blood’s ability to absorb oxygen and possibly the shortness of breath experienced by some. The other DPB’s passed through a UV light can produce cyanide and chloroform, these don’t have the smell of the others but are more toxic. In France they have air quality limits for these chemicals which other countries in the EU do not, including the UK.

Fortunately most of our pools are outdoor and low bather numbers so are easier to maintain by why is what I have written relevant? This is because people do suffer from intolerance of pool treatment chemicals in public pools that they don’t suffer in private pools. Part of the reason is the level of active chemical in the pool. Outdoor pools need cyanuric acid (CYA) as a protection from the sun burning up the chlorine too quickly. This reduces the level of active chlorine (hypochlorous acid) that is available for disinfection whereas an indoor pool does not have any CYA present so the actual hypochlorous acid level could be 10-30 times higher than a domestic pool and if a large number of bathers, say a school party have just been in the nitrogen compounds could be very high so giving rise to the various intolerance mentioned. In clinical terms less than 1% of people are actually allergic to chlorine, it’s almost always the DBP’s to blame. We know this because the water supplied to homes is also treated with the same chemicals and also has chloramines present but generally at low levels compared to an indoor public pool and even asthma and eczema sufferers don’t generally have a problem washing at home. Pre prepared salads are washed in solutions 10 times stronger than the swimming pools we have and that doesn’t cause a problem.

These means that before considering the idea of getting rid of, or not having chlorine in you pool you need to really be aware of what goes on in the water.

I mentioned UV light, it has the ability to reduce chloramines and kill some bacteria and virus but only those that actually get into the chamber. We know that UV light destroys the chlorine in our pools because the suns UV does just that which is why we us CYA to protect it but manufacturers of UV systems tell us it reduces the amount of chlorine you use, it can’t because it destroys chlorine we know that so it must therefore increase the amount of chlorine you use. The biggest point to make is that with an outdoor pool you don’t need additional UV systems because the sun’s UV is millions of times more powerful than a small electric lamp. The sun gives us sun burn very quickly, those little lamps just couldn’t do that so a waste of money.

Ozone, it’s probably one of the most potent killers we have available, underused in most cases. It could do so much more in our daily lives but it must be used with care because it can attack our respiratory systems and kill us too. The other issue is it will only treat a small area of the pool as it is a gas it produces bubbles and these will leave the return fittings and head skyward and therefore no disinfection for most of the pool as it’s very reactive it only has a very short life so would need to be run for a long time to achieve anything. From articles I have studied the air must also be put through a dryer prior to the ozone generator if the ozone produced is going to be of much use. Ozone also attacks some types of plastics like ABS which just happens to be what most pool fittings are made from

Copper/silver mineral treatments, these can be erosion fed metals in a container type setup or and electrical ioniser design. What they do very well is keep algae at bay, copper is great at killing algae, silver also has antimicrobial properties but there are a few issues. They kill very slowly, not rapidly enough to prevent bacteria growing which is why in several countries like Australia they are only allowed to be sold if used with a rapid primary sanitiser like chlorine. In the USA the Environmental Protection Agency (EPA) only sanctions copper as a algaecide for use outside of swimming pools but labels printed by companies often try to flout the law. A colleague of mine reported such mis information and the EPA made the company change their label. They can be used inside a swimming pool but they have not achieved an EPA certificate to do so. The Australians have tightened up their industry, the Americans too have some legislation, the UK and EU haven’t so we are targeted by sales companies for these products. The biggest downside with using copper is the potential to cause staining. It can cause blond hair to turn green and can cause unsightly stains especially on plaster or tiled finish pools.

If we look at the Australian pool market the APVMA insist on a low level of chlorine being present as they carried out test of the efficiency of pool products to kill pathogenic bacteria that could harm humans. None of the gadgets/products tried could pass the test on it’s own so manufactures could only obtain a licence to sell if they used a small amount of chlorine as the primary sanitiser to be present in the pool at all times, simply because chlorine does what we need in most cases, it is lower in cost than most other forms of sanitiser. In most cases the dilution of chlorine required to keep us safe is around 1 part chlorine in 1 million parts of water so very dilute.