Respiratory and Ocular Symptoms Among Employees of an Indoor Waterpark Resort — Ohio, 2016

Epidemiologic Investigation

As part of a 3-day site visit in January 2016, CDC investigators administered a questionnaire to resort employees concerning demographics, work and medical history, and specific work-related symptoms occurring during the preceding 4 weeks. Symptoms were considered work-related if they started at work and improved when away from work. Participants were asked to exclude symptoms associated with a cold or respiratory infection. Employees aged ≥18 years provided oral informed consent. Written informed consent for participation was obtained from parents or legal guardians of employees aged <18 years.

Resort employees in the aquatics department and the waterpark concession stand were classified as waterpark employees (exposed); employees working in other areas of the resort were classified as nonwaterpark employees (unexposed). The frequency of work-related symptoms was assessed. A case was defined as three or more work-related symptoms (eye irritation, nose irritation, cough, wheezing, shortness of breath, chest tightness, or sore throat) of any duration occurring in a resort employee during the preceding 4 weeks. An adjusted prevalence ratio and 95% confidence interval was calculated using log-binomial regression to assess variables associated with meeting the case definition.

Among 112 employees working at the resort during the site visit, 91 (81%) participated. Median age was 19 years (range = 15–65 years), and 47 (52%) were male. Forty-eight (53%) employees reported any work-related symptom, among whom 12 (25%) had taken a median of 2 days off work (range = 1–5), and seven (15%) sought medical care for work-related symptoms in the preceding 4 weeks. The most frequently reported work-related symptoms among waterpark employees were eye irritation (62%), cough (56%), and nose irritation (51%) (Table).

Twenty-nine (32%) employees met the case definition, 24 (83%) of whom were waterpark employees and five (17%) were nonwaterpark employees. Being a waterpark employee and having current asthma were associated with meeting the case definition, but age <18 years, male sex, and being a current smoker were not. After adjusting for age as a continuous variable and current asthma, waterpark employees were more likely to meet the case definition than were nonwaterpark employees (adjusted prevalence ratio = 3.8; 95% confidence interval =1.4–16.2).

Environmental and Ventilation Investigation

In this facility, water features included a children’s play area, activity pool, rain fortress with a splash area and bucket periodically dumping 1,000 gallons of water, four waterslides, and a hot tub and spa. The resort also included a hotel, conference center, bar, gift shop, arcade, concession stand, and office area. The same company had been operating the resort since 2013. Area air samples for endotoxins, chlorine, and chloroform collected on 3 consecutive sampling days at six waterpark locations detected levels that were well below occupational exposure limits (1). Air temperature and relative humidity in the waterpark were logged each minute while the waterpark was open over 3 sampling days. Daily average air temperature was below and relative humidity was above the range recommended for aquatic environments (4).

Water chemistry tests were performed using a standard color-matching test kit at four waterpark locations. Concentrations of combined chlorine, of which chloramines are a subset, in the water were at or above the waterpark’s internal standard of 0.2 ppm on all 3 days of the evaluation, indicating the presence of chloramines. No Legionella or mycobacteria were cultured from water samples from the hot tub and spa.

Assessment of the heating, ventilation, and air-conditioning (HVAC) system identified multiple areas of concern. According to blueprints, the HVAC system design should be able to meet current standards and guidelines in CDC’s Model Aquatic Health Code (5). However, on visual inspection, the fans of five of the waterpark’s six HVAC units were not operational, substantially reducing airflow in the waterpark. The waterpark air distribution system did not provide an airflow pattern with sufficient air movement just above the water surface and deck (where volatilized disinfection byproducts, which are heavier than air, accumulate) to direct contaminated air toward air return intakes. The return air was partially recirculated and the rest was exhausted out of the waterpark through stacks on the roof.

Recommendations

Recommendations based on the hierarchy of controls approach were provided to the resort.* Engineering controls such as maintenance and repair of the waterpark’s HVAC systems and possible reconfiguration of the air distribution system to improve removal of air contaminants just above the water surface and deck were advised, as was encouraging patrons and aquatics department employees to shower before entering the water to reduce the amount of disinfection byproduct precursors (e.g., urine, sweat, skin cells, and personal-care products) that swimmers introduce into the water. CDC also recommends that swimmers take regular bathroom breaks. Other recommendations included encouraging prompt reporting of symptoms by employees to their supervisors and implementation of a system to track and follow up on reports by resort management to identify possible causes and take appropriate corrective actions.

Discussion

Although airborne concentrations of chlorine and chloroform in the aquatic resort were low, a constellation of work-related symptoms consistent with disinfection byproduct exposure was approximately four times more common among waterpark employees than among nonwaterpark employees. Similar respiratory and ocular symptoms have been described in outbreaks at indoor aquatic venues implicating disinfection byproducts (6–8). Water chemistry tests indicated the presence of combined chlorine, including chloramines. HVAC systems, which play an important role in removing air contaminants, were poorly maintained and not operating properly. This was reflected by air temperatures below and relative humidity above recommended ranges. Endotoxin levels were low, and neither Legionella nor mycobacteria was detected during sampling, suggesting that these known causes of respiratory and ocular symptoms associated with aquatic facilities were less likely to have contributed to symptoms at this indoor waterpark than disinfection byproducts. Together, investigation findings suggest that disinfection byproducts and environmental conditions likely contributed to the higher prevalence of symptoms among waterpark employees.

The findings in this report are subject to at least three limitations. First, the evaluation occurred in the winter, a period of potentially lower exposure because the waterpark was open for fewer hours. However, this would likely result in underestimation of an effect. Second, personal air samplers for disinfection byproducts or endotoxins could not be placed on waterpark employees because they could interfere with job duties or get wet and malfunction. This limited the ability to evaluate associations between exposures and symptoms at the individual employee level. Finally, disinfection byproducts are a large class of compounds, but air levels of only one representative member, chloroform, were assessed. Chloramines have been previously associated with irritation symptoms like those reported in this facility (9); however, no reliable analytic method to measure them in air or water currently exists (10).

Indoor waterparks constitute an expanding industry. The first indoor waterpark resort in the United States opened in 1994. By 2015 there were an estimated 192 facilities nationwide, attracting millions of visitors each year. This investigation highlights the need for vigilant monitoring and maintenance of ventilation and water systems to prevent illness in these large, complex indoor aquatic facilities and for public health officials, clinicians, and operators of indoor waterparks to understand the risk for respiratory and ocular symptoms in patrons and employees.