How does UV help improve indoor air quality?
Using UV sanitizers as a secondary or supplemental disinfection system allows pools to operate safely with lower halogen levels. UV water treatment only acts within the light chamber and does not radiate any further through the plumbing or into the body of water. That said, halogens still have to be used to maintain a minimum residual level in the water between passages through the light chamber. However, by lessening the residual levels, fewer chemical byproducts are generated.
As a result, the air quality inside natatoriums with properly treated pools using germicidal UV light is improved because the formation of monochloramines is prevented. This also reduces the smell of chloramines inside aquatic facilities.
There are two main UV light technologies that affect air quality. Low-pressure, high-output UV-lamp technology operates at mono-chromatic light of 254 (nm), which effectively stops the formation of monochloramines. Medium-pressure lamps, on the other hand, use poly-chromatic light that also generates 254 nm of germicidal light combined with other wavelengths to remove di- and tri-chloramines simultaneously. Medium-pressure UV units are better suited for indoor pools and/or bodies of water with high bather loads.
What is the recommendation?
USA Swimming’s Facilities’ Development Department strongly recommends all indoor pools (both new and existing) install medium-pressure UV systems.
While medium-pressure UV technology is more effective at eradicating chloramines, they are better suited for pools with high flow rates on a continuous filtration cycle. Low-pressure UV systems are typically recommended for splash pads with aquatic features that have filtration cycles which may not operate continuously. Further, whether a splash pad is indoors or outdoors, it generally has a smaller volume of water that is turned over more frequently. Once monochloramines are dealt with effectively, the formation of di- and tri-chloramines is disrupted.
The Fallsview indoor waterpark in Niagara Falls, Ont., is one example of a facility that struggled with indoor air quality.
“We installed a UV light system on our wave pool approximately five years ago,” says the waterpark’s operations manager, Brent Gusnowski. “Previous to the installation; however, we struggled with maintaining a low combined chlorine level in the wave pool.”
The wave pool contains 514,816 L (136,000 gal) of water and is operated year-round. At the time, the water feature was the largest contributor to combined chloramines being aerosolized. After a failed attempt to reduce combined chloramines using a chemical additive, the facility manager decided to install a medium-pressure UV-light system.
“Within days of installing the unit, we experienced a tangible, measurable impact on indoor air quality,” said Gusnowski.
Fallsview confirmed the results by testing its combined chloramine levels, which showed they had been reduced significantly compared to the pre-UV installation levels. Under normal operating conditions, the combined chlorine levels for the wave pool—when using the UV system—are now approximately 0.2 parts per million (ppm).
“Since the UV system was installed, we’ve had an overall reduction of customer comments about poor air quality in our facility,” said Gusnowski. “This goes to show, if the water quality isn’t in line, it is impossible for the air quality to be any good. Removing contaminants before they become aerosolized can provide a positive impact on air quality. Many companies push solutions that focus on removing the ‘bad air’ once it’s created; however, it’s more effective to prevent the ‘bad air’ from developing in the first place.”
There is actually a sixth option to reduce chloramine development in the pool environment that was not mentioned. It is not remedial or secondary in nature as are the others, but rather simply the most efficient primary chlorination method being applied within the commercial pool industry. This option is known as High Capacity Venturi Injection. It enables a pool system to stay ahead of the chlorine demand effectively completing the process of oxidation while reducing chlorine use by as much as 40%. UV is a secondary sanitation system effective in reducing existing chloramines which should be considered after the application of a properly sized venturi feed system capable of high capacity feed (#HCF). RB
Actually there is a far superior system available for the prevention and removal of the problematic nitrogen trichloride which causes the corrosion and trihalomethanes which bothers the swimmers. Over one million people swim in pools treated with Hydroxan everyday. Recreational water Treatment must take place in the pool or spa where the bathers are to prevent cross infection and be testable acording to microbiologist Dr Robert Stern. Hydroxan is the low cost answer with 30 years of success.