When officials began shutting down swimming pools in Quebec this past summer due to high levels of bacteria, parasites, and viruses in the water, pool operators across the country must have nervously checked and double-checked their own water quality. Elevated levels of E. coli, C. difficile, Legionella, hepatitis A, and Giardia were found in the Quebec pools. Microbial contamination can cause various symptoms including diarrhea, vomiting, rashes, and respiratory problems. Fecal matter, urine, and sunscreen also showed up in the tests.

Fortunately, no swimmers in Quebec became ill. So now that Lower Mainlanders are heading indoors to swim, should we be concerned about catching something nasty in the pool?

According to Brian Johnston, environmental health supervisor for Vancouver Coastal Health, we have nothing to worry about. “Vancouver pools are in excellent shape,” he said during a phone interview. “Pool operators in the city are generally on top of water quality.”

Twice a year, he said, health inspectors test all 515 pools in Vancouver, including park board–run pools and pools at UBC, hotels, spas, and apartment buildings. The inspectors check pool chemistry—including chlorine levels, temperature, pH (acidity or alkalinity) levels, and water clarity—as well as availability of skimmers (to remove solids), safety equipment, signage, and the facility’s written records.

“If the chlorine level is zero or we can’t see the main pool drain, we would shut down the pool immediately,” Johnston said. The pool would then be super-chlorinated and brought back to provincial public- health standards before reopening.

After the Quebec bacteria scare, Quebec environment minister Claude Béchard imposed new rules. In addition to checking chlorine and pH every three hours, all public pools must now test for bacteria levels twice a month.

“Our policy is to err on the side of caution and to have the facility take the necessary action to remedy the situation immediately, particularly if we find that a pool has no”¦chlorine. Therefore we would seldom conduct a bacterial test,” Johnston said.

While attempting to kill bacteria, some pools in Quebec were later found to be overchlorinated, which creates more problems. “Adding too much chlorine can cause skin and respiratory problems,” Johnston explained. “Symptoms of this imbalance can be coughing, eye irritation, dry heaving, and rashes. Generally, the first indication of this would be experienced by the pool staff.”

In fact, some studies show that perhaps we should be more worried about the effects of chlorine on our systems than anything else in the pool.

Chris Neale, until weeks ago the manager of the UBC Aquatic Centre, agrees. “The problem arises when the chlorine combines with other ”˜organics’ like urine, dander, sweat, perfumes, and suntan oils,” he said in a phone interview. That is when a dangerous chemical cocktail of potentially cancer?-causing “chloramines” is produced. The gases form just above the pool surface. (All the more reason not to pee in the pool.)

In a study by Dr. K. Thickett of the occupational lung diseases unit at England’s Birmingham Heartlands Hospital, results showed that nitrogen trichloride (one of the worst of the chloramines) is a cause of occupational asthma in lifeguards and swim instructors. The study found that when pool staff changed jobs, their asthma symptoms went away.

Neale said he is proud of the sparkling-clean water at the UBC pools, even with 3,000 to 4,000 people coming through daily. He explained that the aquatic centre uses a highly effective diatomaceous-earth filtering system to remove organics in the pool water.

“It’s a very fine filter and it’s very effective at removing organics, so our chlorine demand is lower,” Neale said. “Indoor pools do sometimes have ventilation issues, but it’s usually due to dirty filters, poor air-turnover rates, or pool chemistry not being kept in line.”

The system seems to be working well. “We’ve had very few respiratory illnesses in the last 10 years,” said UBC Dolphins’ assistant swim coach Derrick Schoof in a phone interview. The Dolphins train at the UBC pools and the Vancouver Aquatic Centre. “The air quality in both those pools is very good.”

In Europe, ozonation has been the preferred method of sanitizing pools for 50 years. Ozone technology reduces the amount of organics in the water; chlorine must still be used, but in greatly reduced quantities. Chemicals are added to surge tanks and then put through a filtration system before the “drinking-water standard” water is funnelled into the pool.

Some of the largest pools in North America, including Disney’s water parks, use ozonation. In Vancouver, the YWCA and Century Plaza Spa pools are ozonated.

The first ozone-treated park board pool opened last March at Killarney Community Centre; the new Percy Norman pool at Riley Park Community Centre, scheduled for completion by mid–2009, will be next.