|MadSci Network: Medicine|
In answering your question on just how bad chlorine can be from swimming pools, I first need for you to be aware that there are many different forms of "chlorine" and some of these forms and compounds can be dangerous, not to mention all the other microscopic organisms in the water the chlorine kills. Most chlorine forms and compounds that are in pools are considered safe for humans. However, there are some chlorine forms that can be quite hazardous to the person handling them when using them. One of these forms is chlorine gas. Quite a number of large use pools (public and club swimming pools) use a system of sanitizing the pool water with chlorine gas. Chlorine gas is a great sanitizer but also has several disadvantages. It's a gas that must be delivered in bulky metal cylinders, and when not stored properly can produce their own unique hazards. The chlorine gas then has to be applied to the water through sophisticated metering systems operated by trained personnel. And it's highly corrosive, toxic, and very acidic - due to the H+ and CI - (muriatic acid), the byproduct of its reaction with water. Most regulated pools are required to install separate feeding equipment to add approximately 1.25 pounds of soda ash to neutralize the acidity of one pound of chlorine gas. Even with tablet forms of chlorine, which can be added to private pools, one must use caution and always read the directions. Always use care when opening a container of chlorine. Have as much ventilation as possible when opening containers. Breathing in chlorine gas can knock you right out, and could be fatal. The chlorine gas can create muriatic acid within your lungs and produce measurable damage; but more importantly, chlorine gas can displace the air in your lungs and you can suffocate. Always wear protective handling gear such as eye protection and rubber gloves. If chlorine touches your skin, you should wash it off to prevent irritation. If chlorine splashes in the eye, irrigate with water and contact a physician straight away. The label on the chlorine container will also tell you never, never, never mix chlorine with any other chemical. You could produce a combustible or even explosive compound. This includes mixing two different types of chlorine, or chlorine and bromine. Dirt, debris or any foreign substance (algaecides, alkalis and acids, etc.) can cause spontaneous combustion when mixed with chlorine. Allergic reactions to chlorine are rare; however some individuals have experience skin irritation. Extremely high levels of chlorine in the water could possibly release enough gas off of the surface in certain conditions to render breathing difficulties, but this situation is quite often rare and typically occurs with enclosed pools. It is a common misconception that red eyes and a strong chlorine smell to the water is the result of too much chlorine. Actually, the cause is not enough chlorine! Free chlorine molecules, that is. The combined chlorine compound, called a chloramine, is produced when a free chlorine molecule combines with a nitrogen or ammonia molecule. Common nitrogen compounds come from human waste, such as perspiration, urine and skin proteins. These compounds smell bad, irritate the eyes and skin (far more readily than chlorine gas evolving from the pool water), and get in the way of free chlorine trying to do its job. Shocking or super chlorinating the pool water is then necessary to oxidize, or break apart these compounds. So then, when the eyes burn, and the pool smells over chlorinated, the pool doctor's prescription is to raise the chlorine level ten times the normal amount to achieve "breakpoint chlorination" thresholds which will break apart the chloramine bonds. So in a way, chlorine can be harmful for your lungs; especially if you are handling the chlorine to treat pool water. It's just not necessarily or directly from swimming. Granted, there have been documented cases of individuals with allergic reactions to chlorine and some cases of damage, but only quite rarely. More individuals die from bee stings than allergic reactions to chlorine. The greatest factor in the creation of chloramines is the number of people swimming in a pool. The greater number of people swimming in a pool, the more contaminants are introduced to use up the free chlorine molecules and create the irritating, bad smelling chloramines. I'm sure temperature is a factor as more people are inclined to go swimming when the weather is hotter. Finally, as with all things, there will always be a risk. In swimming, there are always risks: the risk of drowning, hitting your head, etc. The question is to put into perspective the amount of risk with everything else. There is more harm from swimming in water that has not been sanitized properly, which contain all sorts of unhealthy micro-organisms (E. Coli bacteria for example), than the risks from injury in swimming in chlorinated pool water. Technically I'm not one of the best indivduals to answer this question, but being a swimmer myself, I am all too aware of having burning eyes and at times becoming overwhemled by the smell of chlorine. Hope this has helped answer a few of your questions.
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