Guest Column - March 2007
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Aquatic Facility Maintenance

Delivering healthy indoor air quality

By James Hogan

Building and airflow problems

While the dehumidifier typically is blamed for any condensation problems, 80 to 90 percent of these problems are due to poor architectural and airflow designs or installation mistakes.

For example, the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) has established standards indicating that vapor retarders-plastic films or other materials that reduce the amount of pool area moisture migrating through the walls, ceiling or floors of the structure-should envelope the natatorium without any breaks. But many retrofits of dysfunctional natatoriums have revealed gaps, tears or improper seals in vapor retarders. It's not rare for this essential natatorium building material to be completely missing. Uncontrolled moisture migration can cause dampness within the structure and possible biological IAQ issues, such as mold and mildew.

Airflow problems are very common in natatoriums. Fogged or wet windows are leading indicators of airflow problems. Supply air diffusers should be within a foot of all windows with exterior exposure. The air should cover the entire surface of the glass. Overhead ductwork may not be sufficient when windows span a wall from the deck to a high ceiling. Smart architects use under-floor ductwork along with overhead ductwork aimed at the bottom and top of the window surfaces, respectively.

Improper ductwork installation, especially near the dehumidifier, can reduce both supply and return airflow.


Paul Richards suspected something was wrong with the indoor air quality (IAQ) when his swim team members kept developing asthmatic and other breathing conditions. Inhaler use was as common as swim goggles.

Richards, the swim coach and manager of the Dickinson College natatorium in Carlisle, Pa., finally convinced school officials that the lack of proper dehumidification was not only harmful to students, but was taking a toll on the space's infrastructure and an adjacent 80,000-square-foot fieldhouse.

Richards, who has a master's degree in sports sciences with a specialization in aquatics maintenance, management and design, reversed the downward IAQ trend with a new dehumidifier and ductwork.

Today, Richards reports that the facility has a healthy IAQ and it's a lot easier to recruit prospective swimmers.

Water chemistry

Perhaps the easiest precaution a facility manager can exercise is storing pool chemicals in a separately ventilated space away from mechanical equipment. Whether covered or uncovered, these chemicals can cause IAQ problems and prematurely corrode most metal. Therefore, chemicals should be stored in their own designated space and not in a mechanical room.

Many pages could be allotted to proper water chemistry, and most pool facility managers already understand chemical balances and the dangers, especially chloramines production, that exist when this important category is neglected.

Besides health risks to occupants, equipment can be severely damaged by prolonged exposure to chloramines. Typically, all dehumidifiers and other equipment manufactured for indoor pool applications have protective coatings and other safeguards protecting them against moisture and corrosives. However, no mechanical equipment can withstand prolonged exposure to excessive chloramines resulting from poor water chemistry.

The parts of the natatorium must work together. A recreation manager can prevent most IAQ problems by controlling the building construction, the mechanical systems and the pool-water chemistry.


James Hogan is product development engineer at Dectron Internationale, a manufacturer of indoor air quality equipment. In his eight years at Dectron, Hogan has advised hundreds of natatorium building owners with IAQ problems. He also is the director of the Dectron Installation & Service School in Niagara Falls, N.Y. For more information, visit