* Note that this article was from June of 2019. Since then the MAHC has undergone a 5th revision.


Breathing easy: Study targets improving air quality at indoor aquatic facilities - June 16, 2019

 

 

Measuring water/air quality and pool operation

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For each phase of the study, researchers will collect information about the facilities’ water and air quality, and pool operation. Data collection will occur at each pool for a period of one to two weeks. The following are brief descriptions of how researchers will measure and collect this data.

Water quality

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This model will help researchers develop updated guidance on the proper design and operation of indoor pools for acceptable air quality, which will be used to update the Centers for Disease Control and Prevention’s (CDC’s) Model Aquatic Health Code (MAHC).

Researchers will collect water samples from each pool twice per day. The first samples will be collected early in the morning, before swimmers arrive, and the second will be collected later in the day, after a period of heavy bather loads. Researchers will analyze the water samples for:

 

• urea concentration (identified as an important precursor to trichloramine formation in the water);

• pH;

• residual chlorine;

• temperature; and

• volatile compounds (using a technique called membrane introduction mass spectrometry).

 

Air quality

Researchers will use a recently developed monitoring device called NEMo to collect real-time measurements of the indoor air quality at each facility, including relative humidity and concentrations of trichloramine, carbon dioxide, and volatile organic compounds (VOCs). While useful for this study, NEMo is costly to operate and might not be an option for some facilities to use in daily operations. Thus, researchers will also be collecting complementary measurements of each aspect of indoor air quality using less expensive instruments, including relative-humidity temperature meters, carbon dioxide sensors, and VOC sensors.

 

Pool operation

There are multiple characteristics of pool operation that influence the buildup of volatile compounds in the air within an indoor aquatic facility. Researchers will collect information about each of the following characteristics:

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• the air handling system, including return airflow rate, location of supply and return vents, dehumidification, heating, cooling, and air temperature;

• water management, including water recirculation rate, pool water volume, locations of drains and return lines, methods of water treatment, and the locations and operational characteristics of water/spray features;

• pool maintenance, including frequency of filter backwashing and water replacement, and use of cleaning and maintenance chemicals;

• bather load; and

• heating, ventilation and air conditioning (HVAC) system characterization, including basic observations and physical measurements.

Developing updated guidance

The research team will use the information collected during the study to develop a mathematical model that will describe the behavior of trichloramine in indoor pool facilities. A schematic illustration of the mathematical model, which will include information about air and water quality, water treatment processes, the types of pools including presence of any water features and bather load, and the air handling system can be seen in Figure 2.

This model will help researchers develop updated guidance on the proper design and operation of indoor pools for acceptable air quality, which will be used to update the CDC’s MAHC.
 

Indoor air quality guidelines and the MAHC

The MAHC is CDC’s voluntary guidance document that brings together the latest knowledge based on science and best practices to help develop and update pool codes. The guidance is all-inclusive and covers design, construction, operation, and management of public aquatic facilities. If followed, the guidelines in the MAHC can help reduce risk for disease outbreaks, chemical injuries, and drownings.

 

For each phase of the study, researchers will collect information about the facilities’ water and air quality, and pool operation.
 

As the only national all-inclusive model pool code, the MAHC is the ideal vehicle to use for promoting the indoor air quality standards for pools across the country. As of March 16, 2019, there have been five majority adoptions and seven partial adoptions of the MAHC by five states, three counties, and three U.S. government agencies. At least 22 states/counties are in the process of, or considering, adoption.

The current indoor aquatic facility air handling system design, and construction and installation requirements in the MAHC, including minimum outdoor air requirements, specify compliance with American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) standard 62.1, Ventilation for Acceptable Indoor Air Quality. However, reports of health issues linked to air quality at indoor pools are continuing to emerge, concerning members of the aquatic industry and public health alike. This led members of the CMAHC to form the indoor aquatic facility ventilation design and air quality ad hoc committee. The committee’s charge is to:
 

1. Identify and assess factors affecting air quality.

2. Review and evaluate current MAHC requirements to determine if identified factors are adequately addressed.

3. Develop revisions to the MAHC to better address ventilation/air quality design and operational criteria. The lack of needed supporting data regarding the various factors led to the request to conduct the indoor air quality study.
 

The committee will use the study results to propose changes to the MAHC indoor air quality guidelines and share them with ASHRAE for consideration in revising its standards. Members of the CMAHC will vote on these changes at a subsequent triennial CMAHC conference. If the changes pass the vote, the CMAHC will submit them to CDC for approval and inclusion in the next edition of the MAHC. Members of the aquatic industry can join the CMAHC and vote on proposed changes to the MAHC by visiting the CMAHC website at www.cmahc.org.