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Rationale Behind the MAHC

This page summarizes the data that led to CDC creating the MAHC.

Swimming and other water-related activities are excellent ways to get the physical activity and health benefits needed for a healthy life. Americans swim hundreds of millions of times in pools, oceans, lakes, rivers, and hot tubs/spas each year 1 and most people have a safe and healthy time enjoying the water. However, outbreaks of recreational water illnesses (RWIs) have increased significantly over the last several decades 2 and drowning and near-drowning 3-6 and pool-related chemical injuries 7-12 continue to occur. This makes it important that public pools and spas are designed, constructed, operated, and inspected to keep swimmers healthy and safe.

In the United States, there is no federal regulatory agency that regulates aquatic facilities so public pools and spas are regulated at the state or local government level. To assist state and local agencies, CDC has led a national collaborative effort with public health, industry, and academic partners from across the United States to develop a national guidance document, called the Model Aquatic Health Code (MAHC), to prevent drowning, injuries, and the spread of recreational water illnesses at public swimming pools and spas. The MAHC integrates the latest knowledge based on science and best practices with specific code language and explanatory materials covering the design, construction, operation, and maintenance of swimming pools, spas, hot tubs, and other public disinfected aquatic facilities.

MAHC Rationale

Rationale for Improving Health and Safety at Public Disinfected Aquatic Facilities

Over 300 million visits to aquatic venues occur each year making swimming the fourth most popular recreational activity in the United States and the most popular recreational activity for children and teens 1. However, over the past several decades, public aquatic venues have been associated with significant increases in disease outbreaks and the continued occurrence of drowning and injuries. These health and safety issues include:

  • Drowning. Drowning is one of the top causes of unintentional injury death for children older than 1 year 3-4. Non-fatal drowning can cause brain damage resulting in learning disabilities or even permanent loss of basic functioning 5,6.
  • Injuries and emergency department (ED) visits. Injuries linked to pool chemicals accounted for almost 3,000-5,000 emergency department visits per year (2003-2012) 8-12. Almost half of the patients were aged <18 years 8-12.
  • Waterborne illness outbreaks. The number of illness outbreaks associated with recreational water has increased significantly since CDC began collecting these data in 1978 from an average of 15 per year (1993-2002) to 34 per year (2003-2012) 2. Most of the increase is due to outbreaks caused by the chlorine-tolerant parasite Cryptosporidium 13-14. A single outbreak can sicken thousands 15.
  • Public pool and hot tub closings because of public health hazards. A recent study found that 11.8% (about 1 out of 8) inspections of public pools and 15.1% (about 1 out of 7) of inspections of public hot tubs/spas resulted in immediate closure because of serious health or safety hazards 16. Other pool inspection data analyses show similar results 17-18.
  • Evidence of pool water contamination. Sampling of public pool filters shows evidence of contamination (59% [95/161] of samples Pseudomonas aeruginosa positive) and from feces (58% [93/161] of samples E. coli positive) 19. In another U.S. study of pool filters, 8.1% (13/161) of samples were positive for Cryptosporidium, Giardia, or both 20.

Regulation of Aquatics in the United States

In the United States, there is no federal regulatory authority responsible for public disinfected aquatic facilities like pools, waterparks, and spas as there is for natural waters (lakes, rivers) through the US Environmental Protection Agency 21. As a result, the health and safety at public disinfected aquatic facilities is regulated by state and local jurisdictions: 68% of local health departments have public pool inspection programs 22. All public pool codes are developed, reviewed, and approved by state and/or local public health officials or legislatures. Consequently, there is no uniform national guidance informing the design, construction, operation, and maintenance of public swimming pools and other disinfected aquatic facilities. As a result, the code requirements for preventing and responding to recreational water illnesses (RWIs), drowning, and injuries can vary significantly among local and state agencies. State and local jurisdictions spend a great deal of time, personnel, and resources creating and updating their individual codes on a periodic basis.

MAHC Vision, Mission, and Anticipated Health Outcomes

The Model Aquatic Health Code’s (MAHC) vision is "Healthy and Safe Aquatic Experiences for Everyone." The MAHC’s mission is to provide guidance on how state and local officials can transform a typical health department pool program into a data-driven, knowledge-based, risk reduction effort to prevent disease and injuries and promote healthy recreational water experiences. The MAHC provides local and state agencies with uniform guidelines and wording covering design and construction, operation and maintenance, and policies and management of swimming pools and other public disinfected aquatic facilities. The availability of the MAHC provides state and local agencies with the best available guidance for protecting public health so they can use it to create or update their swimming pool codes while conserving valuable time and resources previously used to write or update code language. The guidance will be regularly updated using input from a national stakeholder partnership called the Council for the Model Aquatic Health Code (CMAHC) to keep the MAHC up to date and current with the latest advances in the aquatics industry while also responding to public health reports of disease and injury.

Short-term Outcomes: Use of the MAHC should help reduce the risk of diseases and injuries and promote healthy and safe swimming. We anticipate that the practices promoted in the MAHC will initially lead to the following system improvements:

  • Fewer pool and facility closures
  • More-meaningful inspection and tracking/surveillance data
  • An established research agenda to drive future iterations of the MAHC
  • Enhanced collaboration among stakeholders

Long-term Outcomes: By adopting the practices outlined in the MAHC, jurisdictions should also be able to improve the long-term health and safety of aquatic facilities. This should include a reduced risk of the following:

  • Outbreaks of waterborne illnesses
  • Drowning incidents
  • Injuries from pool chemicals and disinfection by-products
  • Swimming-related emergency department visits

CDC is developing systems to track the impact and potential health improvements related to this national public health effort.

  1. US Census Bureau. Statistical abstract of the United States: 2012. Arts, recreation, and travel: Participation in selected sports activities 2009. [XLS - 45 KB]
  2. Hlavsa MC, Roberts VA, Anderson AR, Hill VR, Kahler AM, Orr M, Garrison LE, Hicks LA, Newton A, Hilborn ED, Wade TJ, Beach MJ, Yoder JS. Surveillance for waterborne disease outbreaks and other health events associated with recreational water — United States, 2007–2008. MMWR Morb Mortal Wkly Rep Surveill Summ. 2011;60(SS-12):1–39.
  3. CDC. Ten leading causes of injury deaths by age group highlighting unintentional injury deaths, United States – 2010. [PDF - 1 page]
  4. Gilchrist J, Parker EM. Racial/ethnic disparities in fatal unintentional drowning among persons aged ≤29 Years — United States, 1999–2010. MMWR Morb Mortal Wkly Rep. 2014;63(19):421-6.
  5. CDC. Drowning — United States, 2005–2009. MMWR Morb Mortal Wkly Rep. 2012;61(19):344-7.
  6. Spack L, Gedeit R, Splaingard M, Havens PL. Failure of aggressive therapy to alter outcomes in pediatric near-drowning. Pediatr Emerg Care. 1997;13(2):98-102.
  7. Anderson AR, Welles WL, Drew J, Orr MF. The distribution and public health consequences of releases of chemicals intended for pool use in 17 states, 2001-2009. J Environ Hlth 2014;76(9):10-5.
  8. CDC. Pool chemical–associated health events in public and residential settings — United States, 1983–2007. MMWR Morb Mortal Wkly Rep. 2009;58(18):489-93.
  9. CDC. Acute illness and injury from swimming pool disinfectants and other chemicals — United States, 2002-2008. MMWR Morb Mortal Wkly Rep. 2011:60(39):1343-1347.
  10. Hlavsa MC, Robinson TJ, Collier SA, Beach MJ. Pool chemical–associated health events in public and residential settings — United States, 2003–2012, and Minnesota, 2013. MMWR Morb Mortal Wkly Rep. 2014;63(19):427-30.
  11. Hlavsa MC, Roberts VA, Anderson AR, Hill VR, Kahler AM, Orr M, Garrison LE, Hicks LA, Newton A, Hilborn ED, Wade TJ, Beach MJ, Yoder JS. Surveillance for waterborne disease outbreaks and other health events associated with recreational water — United States, 2007–2008. MMWR Morb Mortal Wkly Rep Surveill Summ. 2011;60(SS-12):1–39.
  12. Hlavsa MC, Roberts VA, Kahler AM, Hilborn ED, Mecher TR, Beach MJ, Wade TJ, Yoder JS. Outbreaks of illness associated with recreational water — United States, 2011–2012.  MMWR Morb Mortal Wkly Rep. 2015;64(24);668–72.
  13. Painter JE, Gargano JW, Yoder JS, Collier SA, Hlavsa MC. Evolving epidemiology of reported cryptosporidiosis cases in the United States, 1995–2012. Epidemiol Infect. 2016;144(8):1792-802.
  14. Yoder JS, Beach MJ. Cryptosporidium surveillance and risk factors in the United States. Exp Parasitol. 2010;124:31-9.
  15. CDC. Communitywide cryptosporidiosis outbreak — Utah, 2007. MMWR Morb Mortal Wkly Rep. 2008; 57(36);989–93.
  16. Hlavsa MC, Gerth TR, Collier SA, Dunbar EL, Rao G, Epperson G, Bramlett B, Ludwig DF, Gomez D, Stansbury MM, Miller F, Warren J, Nichol J, Bowman H, Huynh B, Loewe KM, Vincent B, Tarrier AL, Shay T, Wright R, Brown AC, Kunz JM, Fullerton KE, Cope JR, Beach MJ. Immediate closures and violations identified during routine inspections of public aquatic facilities — Network for Aquatic Facility Inspection Surveillance, Five States. MMWR Morb Mortal Wkly Rep Surveill Summ. 2016;65(SS-5):1–22.
  17. CDC. Violations identified from routine swimming pool inspections — Selected states and counties, United States, 2008. MMWR Morb Mortal Wkly Rep. 2010;59(19):582-7.
  18. CDC. Surveillance data from public spa inspections — United States, May-September 2002. MMWR Morb Mortal Wkly Rep. 2004;53(25):553-5.
  19. CDC. Microbes in pool filter backwash as evidence of the need for improved swimmer hygiene — metro-Atlanta, Georgia, 2012. MMWR Morb Mortal Wkly Rep. 2013;62(19):385-88.
  20. Shields JM, Gleim ER, Beach MJ. Prevalence of Cryptosporidium spp. and Giardia intestinalis in swimming pools, Atlanta, Georgia. Emerg Infect Dis. 2008;14(6):948-950.
  21. EPA. Beaches. 2014.
  22. National Association of County and City Health Officials (NACCHO). National profile of local health departments. [PDF - 76 pages] 2013. See Page 40.
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