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Hot Tub Safety

Finally, the plane touches down. You spent most of the three hour flight listening to the passenger behind you cough on the back of your head. You claim the three hundred pounds of luggage you packed and lug it across the entire length of the airport. You board the complimentary hotel shuttle and try to unwind as the driver darts in and out of traffic. Once you arrive at the hotel, things begin to look up. The desk clerk hands you your key, points you toward the elevator, and as an afterthought calls, “Be sure to visit our exercise room and take a dip in the spa.” As you wrestle your bags to the elevator, you can just imagine the hot water and bubbles easing away the tension. Spas can be a veritable oasis of relaxation, but are they safe?

For a portion of the population, the answer is no. When submerged in hot water (near 104 degrees Fahrenheit), our bodies’ core temperature is elevated. Extended stays (beyond 15 minutes) can cause a condition known as hyperthermia. Hyperthermia can cause elevated blood pressure and/or drowsiness. Children, the elderly, women who are pregnant, persons with high blood pressure, persons taking prescription medication and persons under the influence of alcohol are especially susceptible and should not use a spa until they have consulted their physician.

Even healthy adults should think twice before entering a spa. When using a spa, the bather’s bodies release sweat, body oils, skin cells, and other substances into the water. In fact, a single bather in spa that is kept at 104-degrees Fahrenheit can lose as much as 3-pints of perspiration in one hour. In a properly maintained spa, the chlorine, or other sanitizer, in the water, oxidizes these contaminants.

When multiple users crowd into a spa, the sanitizer present may not be sufficient to oxidize the contaminants being introduced into the water. Because of the small volume of water in a spa, the amount of sanitizer present is much less than in a pool. A 400-gallon spa, maintained at 4 ppm chlorine, contains only ¼ of an ounce of chlorine while a typical commercial pool may contain 7 pounds of chlorine. Four bathers in this spa are equivalent to 2,000 swimmers in a 200,000-gallon pool. If contaminants are not oxidized, the residue causes cloudy, foamy water and feeds disease causing organisms such as Psuedomonas areuginosa and Legionella pneumophila.

To combat the challenges caused by the small water volume and high temperatures of spas, higher levels of sanitizer are required. The water is also circulated at a faster rate.

So before you take a dip, ask a few questions of the management, such as, “How often is the water drained and refilled?” and “How often are sanitizer levels checked?” Observe the area around the spa; do you see any unsafe conditions or hazards? Is the water clear? Does the spa seem too crowded?

When used with caution and properly cared for, spas can be physiologically and psychologically beneficial, relieving pain from arthritis and minor injuries, stimulating circulation and reducing tension.

Page last updated: May 13, 2021