Because not all persons bathe at surf beaches, drowning rates based on resident population are likely to be underreported. To facilitate more precise drowning risk exposure data, this study aimed to develop a reliable direct observation measure of frequency and duration for surf beach bather exposure to water, by gender and age group. Bathers were defined as persons entering the water to wade, swim or surf with equipment. Observed bathers were systematically selected entering the water in daylight hours at six patrolled or unpatrolled beaches over 10 days. Variables measured were: weather and water conditions, water entries, duration of water exposure, water exposure location and person factors. The dataset comprised 204 (69.6%) males and 89 (30.4%) females, with males more likely to be in an older age group (p < 0.05). Compared to females, males spent longer in the water, were more likely to use surfing equipment, and mainly used a surf zone located farther from the shore in deeper water (p < 0.05). Two factors were significant predictors of bathing duration (adjusted R2 = 0.45): main surf zone occupied (based on water depth and distance from shore); and surf equipment used. The study provides new information about water exposure for bathers at surf beaches and new methods for measuring exposure to drowning risk. The findings suggest that overrepresentation of adolescent and adult males in surf beach drowning statistics is in part a product of greater total exposure to the water plus more frequent exposure to deeper water and bathing farther from shore.
Drowning risk factors may be identified by comparing drowning incidence rates for comparable at-risk populations but precise methods are lacking. To address this knowledge gap, an ecological study extrapolated crude time-duration exposure to water for a specified at-risk sample of surf bathers to estimate the bather population for all wave-dominated beaches in Victoria, Australia, over a four-year summer season period. An incidence rate was calculated using surf bather drowning deaths frequencies matched for time and location. For the sample, 47,341 hours of surf bathing were estimated from 177,528 bathing episodes. Generalising these results to Victoria, the crude drowning deaths incidence rate in the summer season was 0.41 per 1,000,000 person-hours of surf bathing (95% CI 0.37–0.45). Further application of the method, particularly in open water settings, may be used to identify candidate drowning risk factors to advance drowning prevention strategies.