Aquatics: Evaluating Eye & Respiratory Symptoms at an Indoor Waterpark
Each year, millions of people visit indoor waterparks, where a lot of splashing and spraying goes on. To protect swimmers from illnesses, disinfectants such as chlorine are used to kill bacteria. Sometimes not enough chlorine is used to stop bacteria from growing. On the other hand, chlorine can react with substances on swimmers' bodies and lead to eye and respiratory symptoms-even severe breathing problems-especially if the ventilation is poor.
When officials from one city health department began investigating complaints of respiratory and eye symptoms from patrons at an indoor waterpark resort, they also became concerned that waterpark employees might have similar symptoms. As a result, the health department asked the Health Hazard Evaluation Program at the National Institute for Occupational Safety and Health (NIOSH) to help evaluate symptoms among waterpark employees in August 2015. NIOSH is part of the Centers for Disease Control and Prevention (CDC). The Health Hazard Evaluation Program helps employees, union officials, and employers learn whether health hazards are present at their workplace and recommends ways to reduce hazards and prevent work-related illness at no cost to them. A multidisciplinary team from NIOSH evaluated this waterpark resort during two visits.
Background & Focus
Chlorine, the most commonly used disinfectant in aquatic facilities, reacts with nitrogen-containing substances from swimmers' bodies such as dirt, skin cells, sweat, feces, urine and body care products. As a result, chemicals called disinfection byproducts are formed. Levels of disinfection byproducts in the air of aquatic facilities depend on factors such as water chemistry, bather load and hygiene, amount of splashing and spraying, and ventilation. Disinfection byproducts can cause water and air quality issues, as well as respiratory and eye irritation. Infectious agents, such as Legionella and mycobacteria, and chemicals such as the endotoxins released by some bacteria can also cause respiratory and eye irritation.
As part of the investigation, the NIOSH team: surveyed employees about their work and health; tested the air for chlorine, chloroform (a chlorine disinfection byproduct) and endotoxin; tested the water for chlorine, mycobacteria and
Legionella; evaluated the waterpark's ventilation systems; and measured air temperature and relative humidity in the waterpark and other areas of the resort.
What Did the Team Find?
The NIOSH team invited all 112 employees who worked during the site visit to complete a questionnaire; 91 (81 percent) employees participated. This included 45 employees who worked in the waterpark and 46 who worked in other parts of the resort, such as the hotel's front desk, office, arcade and gift shop. Thirty-seven (82 percent) waterpark employees reported at least one work-related eye or respiratory symptom in the past four weeks. Work-related eye and respiratory symptoms were about five times more common among employees who worked in the waterpark than other parts of the resort. The symptoms reported, such as eye irritation, cough, nose irritation, wheeze, shortness of breath, chest tightness and sore throat, were consistent with exposure to disinfection byproducts formed when chlorine reacts with materials from swimmers' bodies.
Levels of combined chlorine (chlorine that has reacted with nitrogen-containing compounds) in the water were at or above the waterpark's internal guidelines, indicating the presence of chlorine disinfection byproducts. Air testing for chlorine, chloroform and endotoxin revealed levels well below occupational exposure limits. No Legionella or mycobacteria were found in the water samples the team collected.
Air temperatures were lower, and relative humidity levels were higher than recommended ranges for aquatic environments, indicating insufficient ventilation. Five of the waterpark's six HVAC units did not function properly, which substantially reduced airflow. In addition, the air distribution design did not allow for sufficient air flow across the pool surface. Ideally, there should be some air flow across the pool surface to push air contaminants just above the water surface and deck toward the exhaust.
The NIOSH team concluded that chlorine disinfection byproducts and the status of the ventilation system likely contributed to the higher prevalence of work-related eye and respiratory symptoms among employees in the waterpark compared with other resort areas. Water chemistry tests indicated the presence of chlorine disinfection byproducts, even though airborne concentrations in the waterpark were low. The ventilation system was poorly maintained and not operating properly, reflected by air temperature below and relative humidity above recommended ranges.
The NIOSH team provided detailed recommendations specific to the waterpark they evaluated in the health hazard evaluation report. The report is available online at www.cdc.gov/niosh/hhe/reports/pdfs/2015-0148-3272.pdf. The evaluation was also described in CDC's Morbidity and Mortality Review, which is available at dx.doi.org/10.15585/mmwr.mm6637a5.
The main recommendations, which similar facilities might find helpful, included:
- Repair and properly maintain HVAC units. Develop an HVAC preventive maintenance schedule.
- Consider adding more return air intakes and air flow at pool level.
- Encourage waterpark employees and patrons to shower before entering the water. This would reduce the amount of substances that react with chlorine to form disinfection byproducts. Regular bathroom breaks are also recommended.
- Encourage employees to report work-related upper respiratory symptoms or other health problems. These problems can be early indications that the ventilation systems are not functioning properly. Managers should implement a system to track and follow up on reports.
Do you think your health is being affected by your workplace? If you are an employer, employee or union official, you can request a health hazard evaluation. Requests can be made to the Health Hazard Evaluation Program in writing or online at www.cdc.gov/niosh/hhe/hheform.html.
Ellen Galloway is a writer-editor in NIOSH's Education and Information Division. Sophia Chiu is a medical officer and board certified occupational medicine physician in NIOSH's Health Hazard Evaluation Program. Nancy Burton is a senior industrial hygienist in NIOSH's Health Hazard Evaluation Program. Kevin H. Dunn is a mechanical engineer and Certified Industrial Hygienist in NIOSH's Division of Applied Research and Technology. All the authors are based in Cincinnati, Ohio. The findings and conclusions in this report are those of the author(s) and do not necessarily represent the views of the National Institute for Occupational Safety and Health (NIOSH). Mention of any company or product does not constitute endorsement by NIOSH.