Association between swimming pool operator certification and reduced pool chemistry violations Nebraska, 2005-2006.

Introduction

Swimming is the most popular children's recreational activity in the United States and the second most popular exercise activity for all ages, with more than 360 million visits to recreational water venues each year (Bureau of the Census, 1995). This popularity is paralleled by growing numbers of reported outbreaks of illness associated with recreational water exposure (Dzuiban et al., 2006). In December 2006, a waterborne disease outbreak occurred as a result of chloramine toxicity in an indoor motel swimming pool in Nebraska (Centers for Disease Control and Prevention [CDC], 2007). Mismanagement of this pool by an uncertified operator with no verifiable training caused the toxicity, which affected 24 persons who experienced ocular and respiratory illness. In this preventable outbreak, five persons required medical attention, including a six-year-old boy who was hospitalized in a pediatric intensive care unit for severe chemical epiglottitis and laryngotracheobronchitis. In response, this pool was inspected by Nebraska Department of Health and Human Services (NDHHS) and closed because of chemical abnormalities that resulted in multiple violations.

Since 1978, the Centers for Disease Control and Prevention (CDC), U.S. Environmental Protection Agency (U.S. EPA), and the Council of State and Territorial Epidemiologists (CSTE) have maintained a collaborative surveillance program for collection and periodic reporting of data on the occurrence and causes of waterborne disease outbreaks associated with recreational water in the United States. In response to the outbreaks detected by this surveillance program, CDC Morbidity and Mortality Weekly Report Surveillance Summaries have offered recurrent recommendations citing the need to maintain adequate pool water chemistry, improve procedures to operate and maintain public pools, and enhance training of public pool operators and staff (Dzuiban et al., 2006; Lee, Levy, Craun, Beach, & Calderon, 2002; Levy, Bens, Craun, Calderon, & Herwaldt, 1998; Moore et al., 1993; Yoder et al., 2004). Throughout the United States, swimming pool operators are responsible for correct maintenance and operation of public pools; however, minimal public health oversight exists (CDC, 2003). As a result, water-borne disease outbreaks are often the direct result of mismanagement of public swimming pools. This indicates a need for standard mandatory education for all public pool operators (Bowen et al., 2007; CDC, 2003; Dzuiban et al., 2006). Despite the probability that mandatory training will prevent recreational water illness, data to substantiate this recommendation are limited.

In response to the December 2006 preventable outbreak of chloramine-associated illness resulting from the Nebraska motel swimming pool (CDC, 2007) and the lack of data to support national recommendations for standard mandatory education for all public pool operators or to demonstrate the benefits, the NDHHS Office of Epidemiology initiated a cross-sectional study of statewide pool inspection data. The objective was to evaluate the association between swimming pool operator certification and training requirements, and water chemistry violations, which are indicators of mismanagement of Nebraska pools.

Methods

For this cross-sectional study of Nebraska statewide pool inspection reports during January 2005-December 2006, the association between pool operator certification and chemistry violations of state regulations was evaluated. Nebraska requires a minimum of one annual inspection per pool (Nebraska Department of Health and Human Services, 2004). Analysis was limited to routine inspection reports containing values for both free chlorine and pH. Unacceptable values for either were used as indicators of mismanagement by pool operators because they constitute serious violations and are grounds for immediate pool closure. Start-up, follow-up, and complaint inspections were excluded. Public swimming pools in Nebraska are designated as either Class A or Class B. Class A includes all municipal public swimming pools. State regulations require these pools in all Nebraska counties to have trained certified operators on site at all times when open. Class B includes nonmunicipal pools operated by motels, hotels, apartment complexes, condominiums, child care facilities, property owner associations, and health clubs. In contrast to the statewide operator certification requirements for Class A pools, only Douglas County and the city of Lincoln in Lancaster County have local ordinances that require trained and certified operators for nonmunicipal, Class B pools. In all other Nebraska counties (n = 91), state regulations do not require operator certification for Class B pools.

By using only inspections from counties without Class B operator certification requirements, Class B free chlorine violations (free chlorine < 2 ppm or free chlorine > 10 ppm) were first compared with those of Class A pools. Then statewide Class B inspections were evaluated by comparing free chlorine violations in Douglas County and Lincoln nonmunicipal pools with those in all other counties that do not have operator certification requirements.

To evaluate pool inspections with regard to pH, the frequency of pH violations for nonmunicipal, Class B pools was first calculated statewide and then by county. Inspections between Douglas County and Lincoln Class B pools were then compared. Water quality reports from public water systems were available in these locations to describe chemical properties of the water supplied by these sources. Prevalence of pH violations is affected by the pH and alkalinity of source water entering pools. Accordingly, to control for potential differences in pH of source water, analyses of pH violations were limited to selected cities in Sarpy County and all of Douglas County. These locations share a metropolitan utilities district and have a common surface-water source for all or the majority of pools. Inspection reports from Sarpy County cities that do not share this water source were excluded. Unlike Douglas County, Class B operator certification is not required in Sarpy County, which is the location of the disease outbreak (CDC, 2007). To evaluate pH violations (pH < 7.2 or pH > 7.8) alone and concurrent pH and free chlorine violations, Class B pool inspections in Douglas County were first compared with those in the selected Sarpy County cities. Class B inspections were then compared with Class A inspections within selected Sarpy County locations only.

Because pools were not inspected with equal frequency, multivariable analysis was performed by using logistic regression to control for frequency of inspection. Adjusted odds ratios were calculated to determine if conclusions on the basis of crude prevalence ratios (PR) alone would change substantially.

Results

This study identified 2,010 routine inspections from 894 Nebraska pools (Table 1). Of these, 214 pools had one inspection and 680 had more than one inspection per pool (median: 2; range: 1-7). In counties without Class B operator certification requirements, Class B pool inspections were more likely (30.9%, 167 of 541) than Class A (13.0%, 60 of 460) to have free chlorine violations (PR = 2.4, 95% confidence interval [CI] = 1.8-3.1). When comparing Class B pool inspections only, free chlorine violations were more likely in counties without (30.9%, 167 of 541) Class B operator certification requirements than in counties with (15.8%, 138 of 876) requirements (PR = 2.0, 95% CI = 1.6-2.4).

TABLE 1
Number of Pools and Routine Inspections by Class Designation and
Operator Certification Requirements

Class B Operator  Number of Pools   Number of Routine
Certification        by Class      Inspections by Class
Requirements
                   A    B   All     A      B    All
       Yes         59  367  426    133    876  1,009
        No        221  247  468    460    541  1,001
      Total       280  614  894    593  1,417  2,010

Of 1,417 statewide Class B pool inspections, 210 (14.8%) reported a pH violation. Of these, 153 (72.9%) occurred in two counties (Douglas and Sarpy). The majority of cities in these counties share a metropolitan utilities district. During 2005-2006, the reported ranges for more than 99% of water supplied from this source were approximately 8.8-9.0 for pH and 83-140 ppm for alkalinity (Metropolitan Utilities District, 2005 & 2006). A water quality report for comparison was also available for the city of Lincoln. In contrast to high pH surface water used by pools in Douglas County, pools in Lincoln use groundwater with pH and alkalinity approximately 7.7 and 188 ppm, respectively (Lincoln Water System [LWS], 2006). Of 876 inspection reports from all Class B pools in these two locations that require trained certified operators, 115 had pH violations. Of these, inspections from pools in Douglas County (n = 580) accounted for 93.0% (107 of 115), and only 7.0% (8 of 115) occurred in Lincoln (n = 296). The majority of pH violations were low (<7.2), indicating overcorrection by operators.

Comparing only Douglas County and Sarpy County inspection reports from nonmunicipal, Class B pools with the shared surface water source, pH violations were more likely in Sarpy County (27.0%, 34 of 126) than in Douglas County (18.4%, 107 of 580) where operator certification is required (PR = 1.5, 95% CI = 1.05-2.04). Inspections in Sarpy County (12.7%, 16 of 126) were also more likely than those in Douglas County (6.2%, 36 of 580) to have concurrent pH and free chlorine violations (PR = 2.0, 95% CI = 1.2-3.6). Comparing inspections from Class B pools with those from Class A pools in only Sarpy County locations, Class B pools were more likely (27.0%, 34 of 126) than Class A (6.5%, 2 of 31) to have a pH violation (PR = 4.2, 95% CI = 1.1-16.5) and also were more likely (12.7%, 16 of 126) than Class A (3.2%, 1 of 31) to have concurrent pH and free chlorine violations (PR = 4.0, 95% CI = 0.5-28.6). Adjusted odds ratios calculated by multivariable analysis to control for frequency of inspection demonstrated minimal change from the corresponding crude prevalence ratios (Table 2).

TABLE 2
Crude Prevalence Ratios Compared to Corresponding Simple
and Adjusted Odds Ratios

Measure of                   Inspection Violation Comparisons
Association

                              Class B Only--Pools without vs.
                           Pools with Certification Requirements

                      Free Chlorine          pH (a)            Both
                                                          Violations (a)

Crude PR (b)               2.0                1.5               2.0

OR (c) (95% Cl)  2.39 (1.85-3.09)    1.63(1.05-2.55)  2.20 (1.18-4.10)
aOR (d) (95%Cl)  2.35 (1.79-3.09)    1.66 (e)         2.19 (1.12-4.27)
                                     (1.00 (f)-2.77)

Measure of          Inspection Violation Comparisons
Association

                    Class B Pools vs. Class A Pools

                    Free Chlorine       pH (a)   Both Violations (a)

Crude PR (b)        2.4             4.2             4.0 (e)

OR (c) (95% Cl)   2.98              5.36            4.37 (e)
                 (2.15-4.13)       (1.21-23.68)  (0.56-34.48)

aOR (d) (95%Cl)   2.90                 5.26         4.33 (e)
                 (2.08-4.08)       (1.08-25.64)  (0.52-35.71)

 (a) All pH comparisons restricted to inspections from selected
locations as described by methods.
(b) Crude prevalence ratios (PR) represent results presented in text
with 95% confidence intervals.
(c) Simple odds ratios (OR) calculated without controlling for
frequency of inspection.
(d) Adjusted odds ratios (aOR) calculated using logistic regression to
control for inspection frequency.
(e) Value not statistically significant.
(f) Rounded to 1.00; actual value, 0.998.

Discussion

This evaluation demonstrates potential benefits of mandatory training and certification for public swimming pool operators. As indicators of pool mismanagement, water chemistry violations of both pH and free chlorine are more common among nonmunicipal, Class B pools in Nebraska counties that are not required to have trained and certified operators. These results underscore the critical role that trained pool operators have and emphasize the potential that operator training has to improve swimming safety and enhance prevention of recreational water illness (Dziuban et al., 2006). Furthermore, this evaluation illustrates that routine analysis of pool inspection data is useful for public health decision making and evaluation of effects of future interventions (CDC, 2003).

These results also indicate that the source of water entering pools (e.g., surface water versus groundwater) and the associated pH and alkalinity affect an operator's ability to achieve and maintain an acceptable pH. High alkalinity increases the water's buffering capacity, and this makes the pH more stable and resistant to change (Addy, Green, & Herron, 2004). Consequently, the combination of high pH and high alkalinity in surface water presents a challenge when pool operators attempt to lower the water's pH and maintain it at an acceptable level. This is a critical consideration for locations where use of surface water predominates (e.g., Douglas and Sarpy Counties in Nebraska). In contrast, the majority of public water supplies in Nebraska provide ground-water with alkalinity and buffering capacity similar to surface water, but with pH at or near acceptable ranges for pools (LWS, 2006). In this situation, high alkalinity is not a problem and actually helps stabilize the pH because no adjustment or only slight adjustment is required to maintain pH within acceptable ranges. Despite lower prevalence of pH violations among pools that are supplied with groundwater, however, chlorine violations are not associated with the chemical properties of water entering pools. Rather, prevalence of chlorine violations depends more on mismanagement of pool water chemistry by operators.

The findings of this cross-sectional study of statewide pool inspection reports are critical for policy decisions in Nebraska. In addition, these findings have broader implications. Since nationwide recreational water illness surveillance was initiated in 1978, CDC and other authors have repeatedly recommended enhanced training of public pool operators and staff to improve pool operation and maintenance procedures in response to growing numbers of waterborne disease outbreaks (CDC, 2003; Dzuiban et al., 2006; Lee, Levy, Craun, Beach, & Calderon, 2002; Levy, Bens, Craun, Calderon, & Herwaldt, 1998; Moore et al., 1993; Yoder et al., 2004). These outbreaks were often preventable and represented a range of illnesses caused by multiple etiologic agents. The following are specific examples of recommendations offered in response to waterborne disease outbreak surveillance findings. In 1993, Moore and co-authors reported that outbreaks of dermatitis were the most frequently reported waterborne disease outbreaks caused by recreational water exposure during 1991-1992. The majority of these outbreaks were directly related to inadequate pool operation and maintenance procedures. The authors conclude that such outbreaks are preventable if pool water is correctly maintained (Moore et al., 1993). In 1998, Levy and co-authors reported that all swimming pool outbreaks during 1995-1996 that were attributed to bacteria were associated with incorrectly chlorinated water and underscored the critical need to maintain adequate chlorination (Levy, Bens, Craun, Calderon, & Herwaldt, 1998). In 2002, Lee and co-authors reported low chlorine levels evident among the majority of investigations of outbreaks caused by Cryptosporidium species (Lee, Levy, Craun, Beach, & Calderon, 2002). Although low chlorine levels are unlikely to have caused such outbreaks, this demonstrated that pool operators had "a disturbing lack of awareness concerning the role of chlorine and pH control as the major protective barrier against infectious disease transmission in pools (Lee, Levy, Craun, Beach, & Calderon, 2002)."

For more than a decade, CDC Morbidity and Mortality Weekly Report Surveillance Summaries have demonstrated results of waterborne disease outbreak investigations and reiterated prevention recommendations (Lee, Levy, Craun, Beach, & Calderon, 2002; Levy, Bens, Craun, Calderon, & Herwaldt, 1998; Moore et al., 1993); however, the desired corresponding decrease in recreational water illness outbreaks was not realized. In fact, a steady increase in the number of reported recreational water illness outbreaks since the 1980s was observed (CDC, 2003; Lee, Levy, Craun, Beach, & Calderon, 2002).

In 2003, CDC evaluated more than 21,000 pool inspections from six sites throughout the United States during May 1-September 1, 2002. A total of 54.1% reported one or more violations. The highest percentage of violations (18.4%) occurred among children's wading pools, followed by medical/therapy (14.3%) and hotel/motel (14.0%) pools. Such pools are classified as Class B in Nebraska. Noncompliant water chemistry values comprised 38.7% of serious inspection violations and were the most common cause of immediate pool closures (CDC,, 2003). These findings emphasize the need for increased vigilance to ensure thorough training of pool operators and staff to prevent recreational water illness and to ensure correct pool maintenance (Yoder et al., 2004). Despite CDC offering recommendations similar to those set forth in earlier reports, however, continued mismanagement of public pools was again apparent during 2003-2004. During this period, treated water venues accounted for 69.4% of waterborne disease outbreaks (43 of 62), and the majority were associated with pools (n = 32). Of 31 outbreaks with known etiology, 19 (61.3%) were caused by chlorine-sensitive organisms (e.g., bacteria, Giardia spp., and viruses) and affected 894 persons. Of 12 additional outbreaks in which the agent was unidentified and 284 persons were affected, pool chemicals or disinfection by-products were suspected in eight, and chlorine-sensitive species were suspected in two. the authors conclude that improved pool operation, disinfection policies, and enforcement are needed to prevent recreational water-associated illness (Dziuban et al., 2006). Despite this ongoing nationwide occurrence of such outbreaks and demonstrated lack of proficiency by public swimming pool operators, the National Swimming Pool Foundation[R] estimated in 2006 that only 20 states had regulations requiring verifiable training for public pool operators (Lachocki, 2006).

Swimming pool operator training will not prevent all pool-associated outbreaks, particularly those caused by Cryptosporidium species, which can be associated with correctly maintained pools (Causer et al., 2006). Mismanagement of public pools, however, has been associated with numerous outbreaks caused by multiple etiologic agents, which can be controlled in correctly maintained pools, and the associated outbreaks can be prevented. As such, mandatory pool operator training might enhance pool-associated outbreak prevention and might also increase operator awareness of infectious disease transmission in pools, water parks, and other recreational water venues (Causer et al., 2006; Lee, Levy, Craun, Beach, & Calderon, 2002; Wheeler etal.,2007).

The findings of this evaluation are subject to certain limitations. These analyses were based on certification requirements for inspected pools. As such, a surrogate measure was used, and the actual presence or absence of trained operators for each pool was not assessed. Inspections were completed by multiple inspectors from eight agencies; however, all inspectors did use Swimming pool inspection forms that collected a standard set of data elements. Additionally, analyses did not account for pools with nonpublic water sources, pools with a common operator, operator experience or level of training, type of chlorination system or pool type (i.e., indoor versus outdoor), age, or size.

Conclusion

The results of this cross-sectional study demonstrate a positive association between swimming pool operator training requirements and acceptable pool water chemistries, which are indicators of correct pool operation and management. This finding substantiates recommendations for nationwide verifiable training for public pool operators and illustrates potential benefits (Bowen et al., 2007; CDC, 2003; Dzuiban et al., 2006). As a result, public health risks associated with public pools might be reduced if operator training and certification are required (as opposed to simply recommended). In response to the results of this evaluation, combined with growing numbers of reported pool-associated outbreaks that are often linked to incorrect pool maintenance and disinfection (Bowen et al., 2007; CDC, 2003; CDC, 2007; Dzuiban, et al., 2006; Lee, Levy, Craun, Beach, & Calderon, 2002; Levy, Bens, Craun, Beach, & Calderon, 2002; Levy, Bens, Craun, Calderon, & Herwaldt, 1998; Moore et al., 1993; Yoder et al., 2004), the swimming pool industry should strongly encourage training for all public pool operators, particularly in locations where training is not required by law. Likewise, operators and staff of public swimming pools, particularly nonmunicipal pools, should pursue training, even if training is not required, and maintain proficiency to ensure adequate management of the pools for which they are responsible. Finally, on the basis of this evaluation's findings and the occurrence of ongoing, nationwide waterborne disease outbreaks associated with inadequate public swimming pool operation (Bowen et al., 2007; CDC, 2003; CDC, 2007; Dzuiban, et al., 2006; Lee, Levy, Craun, Beach, & Calderon, 2002; Levy, Bens, Craun, Calderon, & Herwaldt, 1998; Moore et al., 1993; Yoder et al., 2004), Nebraska and other states and jurisdictions that lack equivalent requirements should consider requiring trained and certified operators for all public swimming pools.

Acknowledgements: The authors thank Mary Sue Semerena, M.B.A., Troy Huffman, R.E.H.S., Jack Daniel, M.E.H., R.E.H.S., and Susan Farnsworth from Nebraska Department of Health and Human Services; Tom Baker, R.E.H.S., M.P.H., and Doug Clark, R.E.H.S., from Douglas County Health Department; and Leon Marquart, R.E.H.S., from Lincoln-Lancaster County Health Department for their assistance with this evaluation. We also thank Anindya De, Ph.D., from the Centers for Disease Control and Prevention for statistical support and all the pool inspectors in Nebraska who performed the inspections and collected the data.

Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.

Corresponding Author: Bryan F. Buss, Epidemiology Field Officer (CEFO), Nebraska Department of Health and Human Services, Division of Public Health, 301 Centennial Mall South, Lincoln, NE 68509. E-mail: [e-mail].

REFERENCES

Addy, K., Green, L., & Herron, E. (2004). pH and alkalinity. University of Rhode Island Cooperative Extension. Retrieved October 1, 2007, from http://www.uri.edu/ce/wq/ww/Publications/pH&alkalinity.pdf

Bowen, A.B., Kile, J.C., Otto, C., Kazerouni, N., Austin, C., Blount, B.C., Wong, H.N., Beach, M.J., & Fry, A.M. (2007). Outbreaks of short-incubation ocular and respiratory illness following exposure to indoor swimming pools. Environmental Health Perspectives, 115(2), 267-271.

Bureau of the Census. (1995). Statistical abstract of the United States: 1995 (115th ed.). Washington, DC U.S. Department of Commerce.

Causer, L.M., Handzel, T., Welch, P., Carr, M., Culp, D., Lucht, R., Mudahar, K., Robinson, D., Neavear, E., Fenton, S., Rose, C., Craig, L., Arrowood, M., Wahlquist, S., Xiao, L., Lee, Y.M., Mirel, L., Levy, D., Beach, M.J., Poquette, G., & Dworkin, M.S. (2006). An outbreak of Cryptosporidium hominis infection at an Illinois recreational water park. Epidemiology and Infection, 134, 147-156.

Centers for Disease Control and Prevention. (2003). Surveillance data from swimming pool inspections--selected states and counties, United States, May-September 2002. Morbidity and Mortality Weekly Report, 52 (22), 513-516.

Centers for Disease Control and Prevention. (2007). Ocular and respiratory illness associated with an indoor swimming pool--Nebraska, 2006. Morbidity and Mortality Weekly Report, 56(36), 929-932.

Dziuban, E.J., Liang, J.L., Craun, G.F., Hill, V., Yu, P.A., Painter, J., Moore, M.R., Calderon, R.L., Roy, S.L., & Beach, M.J. (2006). Surveillance for waterborne disease and outbreaks associated with recreational water--United States, 2003-2004. Morbidity and Mortality Weekly Report Surveillance Summaries, 55(No. SS-12), 1-30.

Lachocki, T.M. (2006). Pool and spa operator training--A smart choice. The Official Newsletter of the National Swimming Pool Foundation[R], 41(4), pp. 5, 12-14. Retrieved October 11, 2007, from http://www.nspf.org/Documents/Newsletters/Vol41_04_2006.pdf.

Lee, S.H., Levy, D.A., Craun, G.F., Beach, M.J., & Calderon, R.L. (2002). Surveillance for waterborne disease outbreaks--United States, 1999-2000. Morbidity and Mortality Weekly Report Surveillance Summaries, 51 (No. SS-8), 1-47.

Levy, D.A., Bens, M.S., Craun, G.F., Calderon, R.L., & Herwaldt, B.L. (1998). Surveillance for waterborne-disease out-breaks--United States, 1995-1996. Morbidity and Mortality Weekly Report Surveillance Summaries, 47(No. SS-5), 1-34.

Lincoln Water System, Lincoln, Nebraska. (2006). Annual drinking water quality report for 2006. Retrieved October 1, 2007, from http://www.lincoln.ne.gov/city/pworks/water/wtrqual/index.htm.

Metropolitan Utilities District, Omaha, Nebraska. (2005). Your 2005 water quality report. Retrieved October 1, 2007, from http://www.mudomaha.com/water/05.ccr.pdf

Metropolitan Utilities District, Omaha, Nebraska. (2006). Your 2006 water quality report. Retrieved October 1, 2007, from http://www.mudomaha.com/water/06.ccr.pdf.

Moore, A.C., Herwaldt, B.L., Craun, G.F., Calderon, R.L., Highsmith, A.K., & Juranek, D.D. (1993). Surveillance for waterborne disease outbreaks--United States, 1991-1992. Morbidity and Mortality Weekly Report Surveillance Summaries, 42(No. SS-5), 1-22.

Nebraska Department of Health and Human Services. (2004). Nebraska Administrative Code, title 178, chapter 2. Operation and management of public swimming pools. Retrieved October 11, 2007, from http://www.hhs.state.ne.us/reg/T178.htm

Wheeler, C., Vugia, D.J., Thomas, G., Beach, M.J., Carnes, S., Maier, T., Gorman, J., Xiao, L., Arrowood, M.J., Gilliss, D., & Werner, S.B. (2007). Outbreak of cryptosporidiosis at a California water park: Employee and patron roles and the long road towards prevention. Epidemiology and Infection, 135, 302-310.

Yoder, J.S., Blackburn, B.G., Craun, G.F., Hill, V., Levy, D.A., Chen, N., Lee, S.H., Calderon, R.L., & Beach, M.J. (2004). Surveillance for recreational water-associated outbreaks--United States, 2001-2002. Morbidity and Mortality Weekly Report Surveillance Summaries, 53(No. SS-8), 1-21.

Bryan F. Buss, D.V.M., M.P.H.

Thomas J. Safranek, M.D.

Julie M. Magri, M.D., M.P.H.

Thomas J. Torok, M.D, M.P.H.

Michael J, Beach, Ph.D.

Brett P. Foley, M.S.