A couple of weeks ago, a hotel pool in Florida was evacuated and 18 people had to be taken to the hospital for respiratory problems. The reason was that two common pool chemicals, muriatic acid and chlorine, were improperly mixed and combined into ammonium chloride gas.
State legislatures regulate pools in a variety of ways to prevent unnecessary injuries, including requiring certain chemicals to be added to the water. The chemicals are intended to balance the pH level, and to keep it clean and sanitary. Those regulations don’t do a lot of good, unfortunately, if pool employees aren’t properly trained on how to maintain those chemicals in a proper mix, or if negligent maintenance allows them to get out of balance.
Chlorine is typically required because it the reduces bacteria in the water. Muriatic acid is another name for hydrochloric acid, and it is used to control the pH, or acidity level, of the water to promote eye comfort while swimming. When the two are improperly combined, however, they can produce ammonium chloride, which can make people sick.
People exposed to ammonium chloride can experience a range of symptoms from minor irritation of the mucus membranes to difficulty breathing and even damage to the lungs.
According to a spokesperson for a commercial spa maintenance company interviewed by WPDE-TV, some pool maintenance professionals consider the risk of using muriatic acid too high and have switched to using other products. Even with proper training and certification, chemical accidents can still occur.
The facts aren’t yet in on whether negligent maintenance or poor training among the pool employees that caused the accident, but the problem could happen anywhere. In fact, many firefighters are certified in handling hazardous materials, and that training includes common chemicals used in pools.
These accidents aren’t limited to summertime -- the same chemicals are used in indoor pools, where ammonium chloride gas exposure could be even more dangerous.
Source: WPDE-TV, "Chemicals required to make pools safe can also be dangerous," Joel Allen, Sept. 24, 2013