Air Quality Information 

It is simply a fact that indoor pools are increasingly experiencing problems with “bad air”.  HVAC (Heating Ventilating & Air Conditioning) systems are designed to control air temperature.  Some of them are designed to control humidity, and air flow with fresh air mix when necessary.  They are not air scrubbers, therefore the air quality is directly affected by the water quality;  bad water = bad air ! ! !   In the past few years, “bad air” has been proven to be coming from chloramines in the water – not chlorine – but chloramines.  This is a chlorine compound that cannot easily burn off in the water.  Chloramines are released during evaporation and when the water is agitated.  They smell like ammonia and can cause serious respiratory problems both for swimmers, staff around the pool, and spectators in the stands. 


Many municipal water companies are artificially adding chloramines in excess of 1.5 ppm (parts per million) to the city drinking water supply.  In these instances, we highly recommend that pools look into installing an activated carbon filter for their make-up water (the water they fill their pool with).  This will drastically reduce the amount of chloramines being added to the pool on a daily basis when fresh water is added.  


Explanation: Many major municipalities and surrounding areas have switched their drinking water disinfection from chlorine to chloramine. Chloramine, a chlorine-ammonia compound, is more stable in the water system than chlorine, and only slowly breaks down into chlorine and ammonia. While both methods, common nationwide, may sound ominous, there's little to worry about, except in special cases. Chloraminated water in dialysis (medical)  fish tanks, and in certain business uses (swimming pools) will need to be specially filtered and treated.  Chloraminated water can also cause rubber parts in plumbing, pumps, filters, and water heaters to degrade more quickly. Chloramine-resistant replacement parts may be available. Chloramine disinfection, however, professes to be preferable to chlorine for almost all uses: drinking, cooking, bathing, gardening, and pets. Your water's taste may improve, the carcinogens called trihalomethanes formed by chlorine will be reduced, and more pathogens will be removed due to chloramines’ extra stability.  As of January 1,  the EPA has begun regulating chlorine, chloramines and byproduct levels in the drinking water of all communities, adding a nationwide level of oversight. Chlorine and chloramine levels are capped at 4 parts per million, but there is no cap set for ammonia. With some municipalities chloramine programs chloramine and chlorine levels are capped at 2 ppm and ammonia at 0.5 ppm.  Others are well above this level.   Chloramine and the small amount of ammonia produced in breakdown are neutralized in digestion, but chlorine can lead to eye and nose irritation, anemia, stomach discomfort, and damaged hair and skin. While the EPA's regulation, and chloramines’ stability, should minimize all these symptoms, there are solutions if you're still worried or if you're one of the special cases mentioned above. Standard water filtration may not really reduce and definitely not  eliminate chloramine and chlorine. While chlorine can be eliminated through boiling water or by letting it stand for a few days, neither method will eliminate chloramines.  To eliminate chloramines in swimming pools, you will need a high quality granular activated carbon filter for source water (make-up water) and a  dechloraminating system like “medium pressure” Ultra Violet.  


USA Swimming’s Facility Development Department has opinions on UV water treatment for chloramine destruction.  We can strongly encourage you to do your own research as to which UV system fits your needs. 


Water in a pool (if balanced perfectly) will pass through the UV system approximately every 6 hours.  That means that the water in the pool has plenty of time to develop monochloramines therefore creating the di's and tri's (chloramines) during the time in the pool with the bathers.  This will happen - it's very natural.  When this water passes through the UV, the mono's might be destroyed but it leaves behind the di's and tri's which get returned to the pool.  Current best information states that the di's and tri's are the worst culprits of odor, corrosion, and irritation.  The water in the pool will have many hours to form these compounds before ever seeing the UV system again.  This is probably the best evidence as to why the right type and size of system is imperative.  


The Facilities Department of USA Swimming strongly recommends that all indoor pools ( both new and existing) have medium pressure UV installed. 
We have also developed a 20 minute CD power point with audio called the Safe-WAY (Water Air & You).  E-mail for information.  


We have been “circling the wagons” with the “pool atmosphere” concept for quite a few years now.  There are literally a dozen or more “expert” opinions on water and air quality and almost all of them have some good points.  At the present time over 50% of the Facilities Development Department’s  “please solve my problem” type calls have to do with poor air quality.  The information listed below is written in lay-persons terminology and may help you investigate and solve your specific problem.
First & foremost, air quality and water quality are dependent on each other.  Air quality will be affected by:

  • The amount of fresh air that is being introduced into the building every hour.  This is totally dependent on outdoor climate and type of building.  A 90% change of air every 20-25 minutes works well in warm areas. 
  • The condition of the air handling equipment filters.  The filters should be cleaned or changed every 3 months.  There are micro-filters that filter out more air-borne contaminates than the standard fiberglass or paper filters.
  • The type of air handling system you have.  Do you have a Desert-Air type system and is it regularly serviced and working properly?  
  • Routine maintenance must be done and tracked on all pieces of air handling equipment.  Vents and louvers must be checked and lubed at least 4 times a year to make sure they are working properly. Dust must be removed from surface of vents.  Motor belts and fuses also need to be checked.

If the air smells like chlorine – something is wrong.  That acrid smell we sometimes associate with chlorine is usually an ammonia type compound.  In the swimming pool industry the “cause of this odor” is called “chloramines”.  Chloramines (combined chlorine) occurs when free chlorine combines with ammonia and other nitrogen compounds.  This “combining process” can be accelerated by perspiration, urine, saliva, body oils, lotions and some shampoos/soaps, fertilizers, many industrial or household cleaners, and the municipal water company adding chloramines to the city water.  The odor is created when water is not properly balanced and the chloramines exceed a certain level.  The odor intensifies when swimmers agitate the water – as in kicking or general warm-up swimming.  The odor is worse at water level but can be extremely irritating at deck level or in the viewing area.  Many times not only an odor is noticeable but eye irritation and difficulty breathing is also experienced.  Sometimes the water may be hazy – but not always.  Many times, the water will appear perfectly clear and the water test for free chlorine and pH reads normal.  


This has become such a widespread problem in indoor pools that literally hundreds people are hospitalized each year.  People with Asthma can find themselves in Intensive Care if exposed to this type of pool condition for even a short period of time.  Most of the problems occur in indoor pools.  Outdoor pools have plenty of fresh air and sunshine (ultra violet light) so they are not as susceptible to the chloramines problem.


Chloramine formation can be caused or accelerated by:

  1. Swimmers not properly showering before entering pool.
  2. People using the pool rather than getting out and going to the restroom. Peeing in the pool has reached epidemic proportions across the country.
  3. People doing a high level of aerobic activity and sweating in the water. (everyone sweats in the water – the same as if they were doing exercise on land)
  4. Residues from ammonia based cleaning products that are used on decks or in shower rooms/lavatories.*
  5. Residues from fertilizers used on landscaping (nitrogen based) that get tracked into building on everyone’s shoes.*
  6. Poor air circulation and lack of fresh air introduction into the pool building.
  7. Over use of “shocking” the pool for maintenance purposes.  Shocking should not be done on a regular basis – there needs to be a really good reason (like killing bacteria that has been found through lab testing) to shock a pool.
  8. Improper use of certain brands of chemicals not suitable for conditions specific to a geographic area.
  9. Municipality artificially adding chloramines (chloramination) to the tap water – a very common practice now days. This has become a big problem the past few years.

*Note - Regardless of proven successful methods for pool operations and common sense approaches to risk management and safety, people who manage or operate pools will still have the right to make bad decisions. That being said, most of the more efficiently operated pools in this country have a “no street shoes on pool deck” rule.  When street shoes are worn on deck just some of the problems that can be created are:

  • Dirt is tracked on to deck and then wet feet walk through that dirt and track it into pool.  If the pool deck has tile the grout in between the tiles will become discolored.  If the deck is concrete, the concrete will trap the dirt and look dingy and dirty
  • Glass – the soles of most shoes have treads and many of them have chards of glass picked up from walking on the sidewalks and streets.  Those tiny chards can end up on the pool deck and eventually in a bare foot.  This causes problems.
  • Cleaning Chemicals – most public places use ammonia based cleaners.  The shoes walk through this all day and every day.  The ammonia from the soles of shoes will come off on the wet pool deck and end up on swimmers feet and in the water.  Even a miniscule amount of ammonia can wreak havoc with the pool water chemistry accelerating the formation of chloramines.
  • Nitrogen – almost every fertilizer uses nitrogen.  When people walk across grass/lawns the chemicals used on the landscaping sticks to their shoes.  The nitrogen compounds will come off on the wet pool deck and end up on swimmers feet and in the water.  Even a small amount of these chemicals can affect the pool water chemistry causing formation of chloramines

The solution is to have all staff wear shoes they only use on pool deck.  All clients and pool users wear water shoes or sandals dedicated for pool room use only.


So – what do we do if this occurs ?    



If Chloramines are detected the most prevalent solution is to “shock” the water.  This means super-chlorination (break-point chlorination) or raising the level of chlorine in the pool to 10 parts per million.  Normally a dry chlorine powder or a liquid chlorine is used to achieve super-chlorination. Recent studies show that many times this is not as effective as Hyper-chlorination which is raising the level of chlorine to 20 parts per million.  Even more recent studies suggest any level of shocking may not be a good idea and may not help the chloramine problem.   


These methods may temporarily “burn out” chloramines but will also necessitate the pool being closed for a few days.  More than the normal amount of fresh air will also have to be introduced during this process.  Shocking the pool can create a whole new set of problems and is at best a very short term solution – if any at all.


Some success has been realized with a non-chlorine shock additive. Adding an Oxidizer (Potassium Peroxy, Monosulphate = brand names Oxykleer or Oxybrite) to the water to convert the available chlorine to free chlorine can release the available chlorine to free chlorine.  If this process is done in the evening, swimmers can usually be in the pool the next morning.  Fresh air introduction is still important.  This is NOT a permanent solution.  It seems to be less and less effective each time it is tried in the same pool. 



Usually more than one thing needs to be changed to alleviate the problem. The most common methods are:

  1. Change the air circulation system to include more fresh air introduction and better turnover or more efficient closed system circulation and dehumidification.
  2. Evaluate the type and brands of chemicals being used to treat the pool water for both chlorine and pH control
  3. Evaluate the pool filtration system to see if a filter that filters down to a more effective micron rating (like DE at 4 microns) would help.
  4. Check the labels on all cleaning products to make sure they do not contain ammonia or are not nitrogen enriched.
  5. Have you staff attempt to get the users of the pool to take showers before entering – this is usually required by state health codes.
  6. Consider installing the right type of Ultra Violet (UV) water treatment system that cuts down on the amount of chlorine you have to use and also “breaks down” mono and di and tri chloramines.
  7. Install an activated carbon filter for your fill or make up water to remove chloramines from the city water.  

When does the pool water need to be changed?


That depends on:

  1. The size of the pool
  2. The water temperature the pool is kept at
  3. The bather load
  4. The type and brand of chemicals used
  5. The type of filter and the turnover rate

In general – the smaller the pool the more frequently the water has to be changed.  Hot Tubs in the 300-600 gallon range need to be drained and refilled at least monthly.  Many State Dept. of Public Health’s require that exact schedule.  


Many specialty pools – such as lessons pools or therapy pools in the 1,500 to 5,000 gallon range need to be drained every 3-4 months.  The warmer the water and the higher the bather load the more frequent the water needs to be changed.


Larger pools – such as lap pools and competitive pools can actually go years before needing to be drained.  Because of the large surface area of these pools exposed to evaporation, new water is constantly being added.  In effect the water is always in a state of renewal.  We have seen pools with perfect water that have not been drained for 4 years or more.  


Some things that can shorten the life of the water and necessitate early draining

  1. Improper chemicals with non-soluble buffers or binders and poorly designed “inert ingredients”
  2. Poor quality filtration
  3. Continually “shocking” pool to break up chloramines
  4. Users not taking showers before entering pool 

Problems cannot be ignored.  Serious health and safety issues are involved.  Everyone who works in an aquatic facility needs to be made aware of the importance of a clean and healthy environment.

The following scenario is happening all over the country in indoor pools.  It usually happens at “big meets” where overcrowded conditions exist in the pool during pre-meet warm-ups and the warm-up pool is overly used all day.  The stands are full of spectators and the deck is full of swimmers – coaches – and officials.  The operational capacity is exceeded both for the building and the pool.  It is seldom - if ever - an air handling issue but rather a water quality issue.  It is primarily caused by the people it affects the most - the swimmers.  


The typical chain of events goes something like this:

  • Pool is fine and ready to go day one.  Massive amounts of swimmers enter the water for warm-ups.  Somewhere as few as 1 out of 3 or as many as 1 out of 2 swimmers will pee in the pool during the first couple hours of the warm-ups.  This same ratio applies to the warm-up pool all day long.
  • Because of this and the swimmers not taking showers before entering the pool, rapid chloramine formation begins.  Air quality begins to be affected by the afternoon session of the first day.
  • If the pool operators “shock” the pool that evening – this only compounds the chloramine build up.
  • The pool seems ok at the beginning of warm-ups the second day but when the large number of swimmers get in and agate the water – the air quality deteriorates rapidly.
  • By the middle of second day the pool and pool room becomes saturated with chloramines in the air and everyone has trouble breathing.  This has a greater negative impact on those with asthma type symptoms in their daily lives.
  • By the 3rd day there is little that can be done because the water is way over the combined chlorine limits and chloramines are everywhere.  Swimmers – coaches – officials – spectators – everyone is affected. 

Medium Pressure UV units installed on the pool water circulation system will greatly help with this problem.  Every 6 hours the chloramines are destroyed.  That is how long it takes for 95% of the water to get from the pool through the filter system and back to the pool.  Of course the swimmers and coaches have to make a concerted effort to stop advocating the concept that it is OK to pee in the pool. 
There is a detailed article that has been posted on our web site for the past 18 months about UV and air/water quality  


“UV or not to be” that is the question

Water treatment is almost always the problem when the air is “bad”. Improperly balanced chlorinated pools can cause Asthma, according to research from several sources. These findings may explain why swimmers are more prone to exercise educed Asthma than athletes in other sports.  "Results show that nitrogen trichloride (produced by high levels of available Chlorine) is a cause of occupational asthma in swimming pool workers like lifeguards and swim instructors," says Dr. K. Thickett of the Occupational Lung Diseases Unit at the Birmingham Heartlands Hospital.  In Dr. Thickett's study, each of the subjects either stopped taking inhaled corticosteroids altogether, or their asthma symptoms resolved significantly once they were placed in other environments away from the swimming pools. Dr. Thickett's study was backed up by research from other European and Australian sources. 


The problem isn't the chlorine, but what chlorine turns into when combined with organics. The organics are contributed by bathers in the pool in the form of sweat, dander, urine and other organics. The chlorine reacts with the organics and produces nitrogen trichloride, aldehydes, halogenated hydrocarbons, chloroform, trihalomethanes and chloramines. Plus now the municipalities are chloraminating the source water so we have even more bad stuff in the water. 


Dr. John Marshall, of the Pure Water Association, an American consumer group campaigning for safer drinking water, states: "It shows we should be paying more attention to the chemicals we put in our water and we should be looking for other alternatives to high levels of chlorination.”   There are options that are safe, and non-toxic, such as treating water with ultra violet light.
With Ultra Violet systems there is a higher initial capital cost to the swimming pool compared to just chlorine feeders. however, over the life of the pool Ultraviolet technologies reduce the on-going operating and maintenance costs. These costs can be significant. Chlorine is famous for destroying pool infrastructures, rusting out ventilation systems and destroying pool liners and coatings etc. UV poses no such problems. The UV/chlorine pool will be much cleaner, which means dirt, grease, oils, organics and other materials will wind up in the filter system much faster than with highly chlorinated systems.
Part of the problem in adopting UV is that many engineers, architects, pool builders and designers are not all that familiar with the technology. Since our engineering, architectural and other technical training have all been geared to Chlorine, it takes re-education to now apply UV. Many people in these industries are reluctant to "shift gears" and take the time to educate themselves about the proper application of UV.
Once pool owners add UV, they realize that they no longer have to put up with red eye, rashes, unbreathable air and the health consequences of over chlorinated pools.
As the technology becomes more prevalent, expect to see more expertise at the local pool builder or pool maintenance companies. However, many of these companies rely on repeat sales of chemicals. These companies are likely to be highly resistant to UV systems as after-sales revenues will drop. However, for pool maintenance companies that are being paid to keep pools clean, UV is great.  They should spend less time maintaining pools and the pools will be cleaner and the water more appealing. In the future, expect UV prices to drop slightly as more consumers become educated, demand for systems will definitely increase.
UV does not replace chlorine but allows you to run a lesser residual chlorine reading and allows the chlorine to be used 100% for disinfesting rather than go into combination with other elements.  Your State department of Public Health will have a copy of your states regulations and limitations for using UV in commercial pool applications.  Each state may have different codes and getting them to lower their required minimum chlorine levels can be very challenging.
What is ultraviolet or UV ?


Ultraviolet light is part of the light spectrum, which is classified into three wavelength ranges:

  • UV-C, from 100 nanometers (nm) to 280 nm
  • UV-B, from 280 nm to 315 nm
  • UV-A, from 315 nm to 400 nm.

UV-C light is germicidal - i.e., it deactivates the DNA of bacteria, viruses and other pathogens and thus destroys their ability to multiply and cause disease. Certain wave lengths also break down chloramines that develop in indoor swimming pool water.


Specifically, UV-C light causes damage to the nucleic acid of microorganisms by forming covalent bonds between certain adjacent bases in the DNA.  The formation of such bonds prevent the DNA from being unzipped for replication, and the organism is unable to reproduce. In fact, when the organism tries to replicate, it dies.
Ultraviolet technology is a non-chemical approach to assist disinfection. In this method of disinfection, nothing is added to the pool water except chlorine and pH control chemicals.  This makes this process simple, inexpensive and requires very low maintenance. Ultraviolet purifiers utilize germicidal lamps that are designed and calculated to produce a certain dosage of ultraviolet (usually at least 16,000 microwatt seconds per square centimeter but many units actually have a much higher dosage.) The principle of design is based on a product of time and intensity - they must have a certain amount of both for a successful design.

  • under sink installs & water vending machines
  • aircraft, boats & recreational vehicles
  • water wells & water cisterns
  • swimming pool & hot tubs
  • farms, ranches & trailer parks
  • schools & hotels
  • aquarium, hatcheries and nurseries

How do ultraviolet purifiers work - Short wave pressure mercury vapor tubes that produce ultraviolet wavelengths are installed in a water tight chamber.  The UV system is installed after the pool filter and the return water to the pool is circulated 100% through the tube.  Approximately 95% of the ultraviolet energy emitted is at the mercury resonance line of 254 nanometers. This wavelength is in the region of maximum germicidal effectiveness and is highly lethal to virus, bacteria and mold spores. Therefore, the water or air that passes through the chamber is exposed to the germicidal UV light and the genetic material of the micro-organism is deactivated, which prevents them from reproducing.  Other wave lengths can actually break down chloramines so make sure you check the difference between low pressure and medium pressure UV. 
Additional information - Topic: Saline pools or Salt Generation Chlorine (same thing)
This is not new technology – it has been in Australia and South Africa for 20 years.   Our departmental position at this point is that Saline pools are NOT more economical or any better than regular Chlorine or Bromine pools.  In fact – if regular indoor pools add a  UV unit – they will be superior to anything saline pools can offer.  Here are some of the problems with salt generated chlorine systems ….. .

  1. The initial cost of the generator is expensive – up to or more than $100,000 for a 50 meter pool.
  2. Equipment that has metal parts will experience more corrosion – e.g.  heater manifolds & elements – pump impellers and housings – valve stems – etc
  3. The chlorine produced from salt is extremely unstable and burns off quickly – especially when exposed to sunlight.
  4. Keeping the water chemistry balanced is a huge chore.  The pool now has to be stabilized and pH tends to bounce and salt content is critical.
  5. Phosphates are a problem – so is hard water.
  6. Dilution is a problem – splash out and evaporation impact these pools much more than a regular pool.
  7. Artificially introduced chloramines (mono-chloramination) by municipal water companies into the city water supply defeats the purpose of salt generation.  More and more cities are going to chloramination for their drinking water.
  8. Pools using salt generation need more chlorine than normal pools – high use is the standard.
  9. The systems once installed are high maintenance – and tough to keep operating at a predictable level.
  10. The cost to replace diodes and parts can be as much as 25% of the system and the manufacturer was very vague on the life of these parts – (from 3 months to 6 months to a year ? heard all three)

If there were no better solution these type of systems would be something to consider but there is UV which helps solve the chloramine build up problem and kills many types of bacteria.  Along with regular chlorine UV is by far the best solution.  We have not seen any studies on buoyancy when comparing saline to regular pools.  The manufactures state this is not an issue.  We will wait until FINA or another reputable conducts a study then we will comment.   For more information on salt generation of chlorine please e-mail  

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