Preventing chlorine gas exposure

by habiba_abudu | April 18, 2019 9:52 pm

By Doug Sackett

[1]

Chlorine use at aquatic recreational facilities is a mainstay of public health protection. In the past few years, however, while infrequent, there have been troubling incidents of accidental exposure of facility staff and patrons to chlorine gas. These events evidently occur internationally. A recent sampling includes:

• April 2018, Newfoundland: At least 10 children were transported to a hospital from a Deer Lake hotel following “a malfunction of the system that pumps chlorine gas into the hotel’s swimming pool. Too much of the gas was pumped in too quickly,” according a quote from a first responder.[2]
• August 2018, Paris: A Disneyland hotel pool was the site of an accidental chlorine gas exposure in which 22 people were treated for nausea or respiratory problems.[3]
• October 2018, California: An equipment malfunction at a swim school in Thousand Oaks caused 19 people to suffer “chlorine poisoning.” The incident sent seven ambulances and four fire engines to the school following reports of swimmers with breathing difficulty.[4]

In the waning months of 2017, a diverse group of pool experts was convened by the American Chemistry Council (ACC) to develop a video to help explain why these incidents occur and how to take appropriate steps to avoid them. The author was one of the stakeholders, representing the Council for the Model Aquatic Health Code (CMAHC), which, through the Model Aquatic Health Code (MAHC), also addresses the need for electrical interlock protection. The ACC wanted to help prevent accidental chlorine gas exposures. Previously, the chlorine industry had produced a similar, short, free video on the safe use and handling of pool chemicals that is available at www.poolchemicalsafety.com. The industry, as the author learned, strives to be good stewards of its products, as it should be.

In addition to the author and an issues manager from the ACC, the stakeholder video development group consisted of representatives of pool associations, government health officials, nonprofit organizations, and pool chemical and equipment manufacturers. Nearly every teleconference was also attended by a talented videographer who seamlessly absorbed the issue and its solution, and translated all of the concepts to video with clarity and precision.

The result of this collaboration was a new, free, approximately nine-minute video titled, “Preventing Unintended Chemical Injection.” [5]The video debuted at the October 2018 meeting of the World Aquatic Health Conference (WAHC) in Charleston, SC. The immediate response of the pool stakeholder audience was overwhelmingly positive; the general sentiment seemed to be, “where has this video been all this time?”

When all is functioning behind the scenes at the pool correctly, chlorine-based disinfectant (for pathogen destruction) and acid (for pH control) are injected into a pipeline of water being pumped into the pool following a run through the filter (Figure 1). But accidental chlorine gas emissions into aquatic facilities can occur when an electrical interlock between the pool water circulation pump and the chemical feed system is lacking, improperly installed, or simply fails.

If the pool water circulation pump stops (due to some unforeseen problem or perhaps intentionally for maintenance) and the chemical feed equipment continues to add chlorine-based disinfectant and acid into the lines, the two chemicals may react to form chlorine gas (Figure 2), which displaces pool water in the line, the amount being proportional to the length of time the circulation pump is out of service, and chemical feeders are operating. Then, when the pool circulation pump is re-started, chlorine gas is pushed through the lines and out into the pool area where swimmers or staff may be overcome by an unexpected surge of gas (Figure 3).

Electrical interlock

The video makes the point that an unintended injection of chlorine gas into a pool can be avoided by properly designing the system to include electrical interlock protection. Simply stated, electrical interlock protection ensures that if the pool pump is disabled, the chemical feed equipment will also be disabled, avoiding the development of chlorine gas in the lines.

There are various levels of interlock protection, ranging from ensuring the circulation pump and chemical feed equipment are on the same electrical circuit to installing an interlock safety switch. The video also addresses the human factors that may contribute to chlorine gas releases and the importance of good practices among pool staff, including:

• Training staff to recognize high-risk scenarios that could lead to accidental chlorine gas exposure.
• Removing all bathers and staff from the pool and deck whenever: maintenance is performed on the circulation or chemical feed systems; a ‘no flow’ condition is detected; an unexpected or manual deactivation of the circulation pump occurs; or when the interlock system is activated.
• Prohibiting re-entry into the pool until the cause of an interruption in water circulation is understood and corrected and the system is functioning correctly for at least five minutes with an appropriate free chlorine level and pH.

The author had the pleasure of presenting the new video to another audience of pool experts at the November 2018 Association of Pool & Spa Professionals (APSP) International Pool and Spa Expo in Las Vegas, Nev. Here, the audience’s response to the video was gratifying, and many people were seen jotting down the web address for the video. The stakeholder group that developed the video still meets regularly by teleconference to discuss ways to promote the video.

Through the efforts of the ACC in leading the development, promotion, and distribution of this informative and educational video, and the MAHC, which reinforces the related design and operational criteria with model code requirements, the association hopes to see a significant reduction in accidental chemical injection. It will know it was a success when unintended chlorine gas exposures at aquatic facilities are a thing of the past

[6]Doug Sackett is the executive director of the Council for the Model Aquatic Health Code (CMAHC). He has held this position since October 2014. He worked in the pool and bathing beach programs in addition to numerous other environmental health regulatory programs throughout his 38 years with the New York State Department of Health before retiring in 2013. Beginning in 1987, he was involved in the management of the statewide pool and bathing beach regulatory program, including the co-ordination of investigations of illnesses associated with recreational water and drowning at regulated pools and beaches throughout the state and for the analysis of the data from these epidemiological investigations. Sackett was the director and steering committee member for the Centers for Disease Control and Prevention’s (CDC’s) project to develop the national Model Aquatic Health Code (MAHC) from its inception in 2007 until the first edition was launched in August 2014. He was instrumental in setting up the CMAHC as the vice-president and treasurer of the interim CMAHC board of directors. He can be reached via e-mail at dsackett37@gmail.com.

Source URL: https://www.poolspamarketing.com/trade/features/preventing-chlorine-gas-exposure/

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