Ozone solves mysterious health problem.

Something was causing lifeguards at the Westminster City Park Recreation Center to contract a mysterious illness. The problem caused the community pool to close, not just once but twice. The pool's very future depended on solving this mystery.

Fortunately for Westminster, it didn't take Sherlock Holmes or Miss Marple to finger the culprit. After two of the stricken lifeguards saw pulmonary specialists, the illness was identified as Hypersensitivity Pneumonitis (H.P.), a respiratory illness that is very unusual and difficult to diagnose. Symptoms of H.P. may include coughing, shortness of breath, fever, chills, and muscle aches. Diagnosis is made through chest x-rays, bronchostapy tests, blood tests, exercise physiology exams, and lung biopsies. Once correctly diagnosed, the illness was treated successfully.

The City of Westminster then turned its attention to determining what caused its lifeguards to contract H.P. After much research, Westminster and a team of experts focused on the air in the natatorium and completely renovated the air handling system, increasing air turnover threefold. The pool was reopened on May 26, 1990.

Seeking a Solution to Unsolved Mystery

Pool attendance immediately returned to previous levels. Unfortunately, H.P. also returned, causing several new lifeguards to become ill.

Again, the pool was closed.

At this point, the task force formed to solve the mystery looked to the water as a possible culprit. The group suspected that contaminants from the pool's water, when aerosolized through the water features, were being inhaled, causing H.P. Supporting this were endotoxin readings for the City Park pool, which were higher than other area pools tested. This indicated that the chlorine used to disinfect and oxidize the pool water was ineffective in this particular pool. Using an ozone-based water disinfectant system was suggested as a possible solution.

Investigating Ozone

The Westminster task force chose to research ozone and uncovered some interesting facts. For instance, ozone companies in the United States could not provide any scientific evidence to support claims of their products' ability to provide superior water quality. And all of the companies advocated using ozone as a supplement to chlorine, not a substitute.

An article on German standard ozone disinfectant systems by Dr. Rip Rice and a meeting with a local German ozone representative motivated the Westminster team to research ozone further.

Dr. Rice detailed the Germans' development of ozone as the primary disinfectant for indoor leisure pools and provided scientific data on the effective kill-ratio for all sorts of viruses, bacteria, cysts, and other organics. Although there was no specific information about endotoxins, the supporting data on bacteria and other contaminants led the task force to believe that ozone also would handle the endotoxin problem.

Dr. Rice and swimming pool expert, Kent Williams were retained by Westminster to review the situation and advise a course of action. They were confident the German ozone process could solve the problem.

As a last step, a carefully selected task force traveled to Germany to inspect ozone equipment manufacturing facilities and talk to pool operators and employees and German Health Department officials.

In Germany the group learned:

* Almost all of Germany's indoor pools use German DIN Standard ozone technology, and all pools must comply with this standard by 1998.

* The Germans have been studying pool physiology, i.e., bacteria diseases, health effects, etc. since 1966. Experiments and studies are conducted in test pools.

* German government standard technology is a complicated process using flocculation, multi-media filtration, ozone, granulated activated carbon (GAC) filtration, and minimal chlorine application.

* Most European countries are adopting these standards to disinfect indoor spa and swimming pool water.

* There are no recorded cases of H.P. in Germany.

* These treatments are considered by most European aquatics professionals as the most complete and thorough disinfecting processes used in swimming pools today. The purity of water is unsurpassed.

Ozone's Modus Operandi 

The first step in the process (see Figure 1) involves discharging approximately eight gallons of water per person to waste, along with replacing the discharged water with equal volumes of makeup water into a surge tank. From the surge tank, a flocculant is added to "bind" some of the organics together. This process removes some of the contaminants from the water prior to ozonation.

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The water then is filtered through huge multi-layered sand filters. The filter flow rate is very slow (five gallons per square foot) and does an effective job of removing debris.

The next step is ozone production and application. Coronna discharge ozone generators are placed in modules producing 40 to 85 grams of ozone per module. These modules can be interconnected so that large amounts of ozone, up to 1,200 grams per hour, can be produced. Air dryers dry and cool the air to 65 degrees Celsius before passing into the ozone generator.

Ozone is produced when an oxygen molecule is split by something such as a high voltage electrical charge (see Figure 2). This produces two oxygen atoms that then can attach themselves to oxygen molecules. These split atoms are highly active; and when they loosely attach themselves to an oxygen molecule, they become ozone. When the ozone atoms come in contact with other organics, they immediately detach themselves and attack whatever foreign matter crosses their path. The result is a complete and thorough oxidation of bacteria, cysts, viruses, and other contaminants; it also eliminates endotoxins. This is the most effective method of disinfection known.

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The ozone then is injected in the form of tiny bubbles into the water through venturi-type injectors. Millions of tiny ozone bubbles churn and mix with the water. During the reaction time, ozone oxidizes millions of micro-organisms present in the water. The reaction time required for effective kills of most organics is approximately two to three minutes.

From here, some of the excess ozone is passed through a degasser, destroyed, and returns to oxygen. The ozonated water then is run through a GAC filter where any remaining ozone, chlorine, and residual micro-organics are removed completely.

The last step in the process is the addition of a .2ppm to .4ppm chlorine residual and return of the treated water to the pool. Minimal chlorine is added to handle the contaminants brought into the pool by bathers. This method of treating water results in the purest pool water available.

A unique ozone system was designed specifically for the pool at City Park Recreation Center. The pool's redesign was done by Chuck Newman of Water Technology Associates, Beaver Dam, Wisconsin. The new system's construction and implementation took two years and included building an addition to house ozone related equipment, installing a new gutter system to increase the rate of water turnover, and separating the play pool from the other pools to treat and disinfect both areas adequately. The final design and sequence of the process was altered so that the ozone and contaminated water were mixed directly from the surge tank to the contact tank. Flocculation, filtration, and chlorine injection then followed.

Since the City Park Pool began using ozone, water turnover rates exceed industry standards. While Colorado state regulations call for a complete turnover in a pool's water once every six hours, the turnover rate in the deep pool and the recreation pool is once every three hours and once every hour in the play pool.

Other benefits of ozone have surfaced since the system's installation. Since ozone is such a powerful disinfectant, it does not produce undesirable by-products that may cause a trihalomethane odor or eye and nose irritation. The ozone generated has no effect on the environment and never is present in the pool itself. Disinfection of the water takes place in the contact tank in the pool's mechanical room. The GAC filter completely removes the ozone before it returns to the pool.

Westminster City Park Pool reopened in September 1992. The new lifeguards hired were monitored by the Colorado Department of Health for 10 months. Through questionnaires, interviews, and medical examinations, the Department concluded that further active surveillance of pool employees is unnecessary.

Endotoxin tests have revealed the pool's water to contain 1.2 nanograms per milliliter, 100 times lower than the pool's reading the first time the pool closed and 10 times lower than control pools (using standard chlorine) tested before the Denver metropolitan area.

This case was solved not be a wily sleuth or back street private investigator but by cooperation between private and public agencies and national and international experts. This cooperation led to a solution that rid Westminster's City Park Pool of H.P. These efforts--and the ultimate solution--has set an example than can help other communities solve similar mysteries and eventually prevent such problems from occurring in the first place. Then the case truly will be closed.