Development and trial of a water exposure measure of estimated drowning risk for surf bathers

To better address drowning issues, risk assessment at the group and sample levels would be enhanced by precise measures of exposure to water. The aim of the study was to develop and pilot test a method of measuring exposure to water based on estimating immersions for surf bathers. Validated direct observation counts provided peak-bathing period point estimates and a daily bather immersion profile for an identified sampling frame comprising 20 beaches over 39 summer days. An estimated 10,089 water immersions occurred at the peak-bathing period in the sampling frame. Swimmers comprised 86.0 and surfers with equipment 14.0 of the observed bathing sample, respectively. For swimmers only on patrolled beaches, 77.1 bathed in the lifesaver supervised (flag) zones. The study has implications for the provision of organized bather supervision and provides a foundation for generation of hypotheses on the nature of drowning risk for selected surf bather groups.