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The ocean lifeguard drowning prevention paradigm: how and where do lifeguards intervene in the drowning process?
  1. William Koon1,
  2. Ali Rowhani-Rahbar2,3,
  3. Linda Quan3,4
  1. 1 Department of Global Health, University of Washington School of Public Health, Seattle, Washington, USA
  2. 2 Department of Epidemiology, University of Washington School of Public Health, Seattle, Washington, USA
  3. 3 Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington, USA
  4. 4 Emergency Department, Seattle Children’s Hospital, Seattle, Washington, USA
  1. Correspondence to William Koon, Department of Global Health, University of Washington School of Public Health, Seattle, WA 98105, USA; wakoon{at}


Drowning is a global health problem that can be addressed with multiple strategies including utilisation of lifeguards in recreational swim areas. However, few studies have described lifeguard prevention activities. We conducted a retrospective analysis using lifeguard activity data collected in real time with a Computer-Aided-Dispatch (CAD) system to characterise the nature of lifeguard primary and secondary drowning prevention at a popular ocean beach in California. Preventative actions constituted the majority (232 065/423 071; 54.8%) of lifeguard activities, while rescues represented 1.9%. Most preventative actions and rescues occurred during summer months, weekends and afternoons. Statistically significant geographical clusters of preventative actions were identified all over the beach, while rescue clusters were primarily restricted to two sites. Using the most reliable and valid collection system to date, these data show spatial and temporal patterns for ocean lifeguard provision of primary prevention as well as secondary drowning prevention (rescue).

  • Drowning
  • Lifeguard
  • Rescue
  • Prevention

Statistics from


Approximately— 372 000 people die from drowning every year worldwide.1 International consensus-based guidelines recommend the presence of lifeguards where swimming occurs as an important strategy to prevent drowning.2 Open water lifeguard effectiveness literature is limited.3–6 Anecdotal and experiential evidence, expert opinion and incident counts of varying accuracy and reliability have been the primary source for understanding lifeguard activity and effectiveness.

Few studies have described what lifeguards actually do to prevent drownings,7 8 partially due to data collection challenges.9 To better inform lifeguard efficacy, research is needed to characterise the nature of lifeguard duties and expand the scientific basis for operational organisation and practice.

We characterised the spectrum of ocean lifeguard prevention activities in Newport Beach, California using a Computer-Aided-Dispatch (CAD) system that collects data in real time, described primary drowning prevention as actions occurring in the pre-event phase, secondary drowning prevention as ocean rescues occurring in the event phase10 and examined variation of preventative actions and rescues by time and location in order to identify opportunities for increased efficacy of lifeguard primary prevention.


The data used in this study comprises lifeguard preventative actions and rescues recorded with a CAD system by Newport Beach (NB) Lifeguards from 1 January 2015 through 31 December 2016. CAD data were space-time linked to lifeguard work schedules to evaluate variation in staffing and activity. NB Lifeguards granted access to lifeguard CAD data and work schedules. Institutional Review Board approval was not required for this study as it used previously collected de-identified data.

Study location

Newport Beach is a suburban city in Southern California, USA, with 13 km of Pacific Ocean beach attracting approximately 10 million visitors per year.11 Organised as a branch of the NB Fire Department, lifeguards patrol 10 km of ocean beachfront divided into three locations called Divisions. The department employs approximately 245 professional lifeguards (15 full time and 230 seasonal), all trained as Emergency Medical Responders.

Data collection

Lifeguard dispatchers record all interventions with the public in real-time via SunGard Systems Computer-Aided-Dispatch Integrated Public Safety Software. Lifeguards are stationed in towers or vehicles and alert a dispatcher via closed circuit telephone or radio if they are required to leave the station to conduct an intervention. Lifeguards also call dispatch after completing an activity. The dispatcher records the time, location and nature of call (eg, preventative action, rescue, first aid, patron contact (any contact with a beach patron not related to safety, first aid or rule enforcement), surfer warning, major medical, etc) into the system, then organises the incident response allocating resources appropriately. Of the 89 classified lifeguard interventions in the CAD system, those of interest for this study were preventative actions and rescues.

A preventative action is a verbal warning by a lifeguard to a beach patron regarding an aquatic hazard or danger, sometimes provided with loud speakers from a vehicle or boat to large groups and recorded as the estimated number of patrons reached with the warning message. Preventative actions represent ‘reactionary’ prevention on the drowning timeline.10

A rescue is a physical assistance provided by a lifeguard to a patron from the water to a place of safety (eg, boat, shallow water, land) and recorded as the number of people rescued. Rescues in the beach environment represent secondary prevention, occurring in the event phase of the drowning timeline, after the patron is in stress or distress. At the time of this study, lifeguards did not differentiate rescues based on severity; both critical lifesaving rescues and less serious physical assists (eg, to someone scared or struggling in the water) were classified as ‘rescues’.

From lifeguard work schedules, we included active patrol hours when lifeguards were watching the water or were capable to respond to an emergency in their assigned Division. Excluded were hours for training, meetings, administrative duties and night-time standby.

Data analysis

We used the dplyr package in Rstudio to clean, link and calculate summary statistics.12 13 Graphics and maps were created using R packages ggplot2 and ggmap14 15 and Tableau Desktop. Frequencies of lifeguard interventions and staffing by time and season were calculated to characterise temporal variation in lifeguard activity. Rates of interventions per 100 work hours were calculated to quantify activity standardised for the number of lifeguards working and the ratio of preventative actions per rescue to explore the relationship between primary and secondary drowning prevention.

SaTscan software, V.9.4.4, was used to detect geographic clusters of lifeguard rescues in the study area employing Kulldorf methods of a discrete Poisson purely spatial model.16 The analysis compares rescues in a spatial cluster to the distribution of expected rescues if locations of all rescues were independent.17 Relative risks were calculated as the estimated risk within a cluster divided by the expected risk in the rest of the study location, using Monte Carlo replication to explore the distribution and determine statistical significance, set at 0.001, of each spatial cluster.18 Frequency density maps with statistically significant geographic clusters of interventions in the study location were created to demonstrate variation in spatial distribution of preventative actions and rescues.


There were 423 071 unique lifeguard interventions recorded in the CAD system between 1 January 2015 and 31 December 2016 in NB. The majority of lifeguard interventions were Preventative Actions (54.85%, n=232 065), followed by Public Contacts (32.26%, n=136 472), Surfer Warnings (6.53%, n=27 632) and Rescues (1.9%, n=8046) (Figure 1). Of the 193 177 total lifeguard work hours during the study period (Figure 2), 174 802 work hours (90.49%) were for active patrol or quick response to an emergency.

Figure 1

2015 and 2016 Lifeguard Interventions by Month (% from monthly totals).

Figure 2

Lifeguard Staffing by Division and Month (% from Monthly Totals).

Temporal variation in primary and secondary prevention

The majority of both lifeguard preventative actions (73%, n=1 69 415) and rescues (70.7%, n=5691) occurred during the summer months of June, July and August and between the hours of 13:00 and 16:00 (57.8%, n=134 075, of preventative actions and 64.6%, n=5198 of rescues). Both were greater on the weekends with 41.3% (n=95 799) of preventative actions and 46.9% (n=3771) of rescues occurring on Saturdays and Sundays (Figure 3).

Figure 3

Lifeguard preventative actions and rescues by hour and day of week.

Although lifeguard staffing was greatest during July and August, high rescue frequency continued into September and October, when staffing levels were reduced. For the entire study period, the rate of preventative actions per 100 work hours was 132.8 and rescues per 100 work hours was 4.6. The highest rate of preventative actions occurred in July (210.4) followed by June (190.7), September (137.4) and March (128.8). The month of July also had the highest rate of rescues per 100 work hours (6.48), closely followed by September (6.3).

There were 1158 instances in the study period when dispatchers recorded simultaneous preventative actions and rescues for the same lifeguard, indicating different interventions at the same time or in quick succession, most commonly for different patrons. In these instances, lifeguards provided an average of 8.32 preventative actions per rescue,

Spatial variation in primary and secondary prevention

Preventative actions occurred in 15 statistically significant geographic clusters evenly distributed spatially throughout three operational Divisions, but rescues occurred more frequently in only six specific locations. (Figure 4 Frequency density and statistically significant clusters with corresponding relative risks.) The most rescues (n=1922; 23%) clustered around Towers 17, 18 and 19; lifeguards in this location were 3.16 times as likely to conduct a rescue compared with those working in other locations on the beach (p<0.001).

Figure 4

Frequency density map of lifeguard preventative actions and rescues shown with statistically significant scan statistic spatial clusters and corresponding relative risk measures. Red circles indicate spatial clusters, label of each red circle indicates numeric relative risk for that cluster and can be interpreted as the increased likelihood that a lifeguard will conduct a rescue inside the circle compared with lifeguards on any other section of beach.


This study of ocean lifeguard interventions collected in real-time enhances our understanding of the work that ocean lifeguards do and provides evidence for data driven policies and training. Providing new insight to the nature of lifeguard primary and secondary drowning prevention, it shows that primary prevention dominates ocean lifeguard activity and that lifeguard preventative contacts and ocean rescues do not occur randomly in time and space.

The CAD system provided quantitative evidence for lifeguard knowledge that rescue frequencies were location specific. Explanations could include differing beach access and thus patron exposure throughout the study area. However, the impressive rescue clustering in the Division 1 area and near Newport Point suggests that crowds were not the sole determinant of rescue frequencies, a conclusion also reached in an Australian lifeguard rescue study.8

This study has important implications. The persistently high frequency of lifeguard interventions, especially rescues before and after summer suggests increased lifeguard staffing is warranted for these months. Allocating additional staff to areas where rescues are statistically more likely to occur may allow for higher levels of preventive actions, potentially increasing lifeguard effectiveness by decreasing need for rescue and/or reducing emergency response times.


This study’s limitations include lack of data for patron characteristics (age, race, residence, swimming ability, alcohol use or activities), prevention advice given, severity of rescue and beach patron counts. Additionally, dispatchers could have misclassified lifeguard interventions or failed to record interventions, especially when lifeguards reported simultaneous rescues and preventative actions, although errors were probably minimal.


Detailed, valid and reliable data on ocean lifeguard activity provides opportunities for quality improvement, allocation of finite resources and lifeguard training. Improving surveillance methods for lifeguard activity, with an aim to increase the validity and reliability of data collected, should be a priority for lifesaving agencies.

What is already known on this subject?

  • International consensus guidelines recommend swimming in front of a lifeguard as an important drowning prevention strategy.

  • Recording lifeguard activity data has been difficult in the beach environment due to balancing dual water safety and data collection roles assumed by lifeguards.

  • Lifeguards’ role in drowning prevention is secondary prevention, the rescue of swimmers in trouble.

What this study adds?

  • The majority of lifeguard activity is the provision of primary prevention.

  • Lifeguards’ primary preventative actions and rescues follow specific temporal trends.

  • Lifeguard rescues may occur with greater frequencies at specific locations.


The authors thank Newport Beach Fire Department-Marine Safety Division Assistant Chief Rob Williams and Battalion Chief Michael Halphide for their assistance with data acquisition. We also thank Melissa Moulton from the University of Washington Applied Physics Laboratory for consulting on ocean dynamics pertinent to ocean lifeguard rescues.



  • Contributors WK and LQ led study conceptualisation with input from AR. WK was involved with data acquisition from Newport Beach Lifeguards and provided GIS analysis. WK, AR and LQ were involved in data analysis. WK and LQ drafted the paper. AR reviewed it and suggested changes. All authors approved the final document.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement Unpublished data from the study reside with WK, who would share them with permission from the Newport Beach Fire Department-Marine Safety Division.

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