Emergency medical services personnel operating under code-3 (i.e. lights and sirens) has been debated for its utility because the risk of collisions that result in injuries and fatalities increase under emergency-use driving (Figure 2). The positions of the National Association of EMS Physicians (NAEMSP) and the National Association of State EMS Directors (NASEMSP) is that EMV should operate under lights and sirens only during life-threatening situations in which savings in transport time might have clinical significance. Sanddal et al.  review of the literature on lights and sirens suggest that the time saved when an ambulance operates under code-3, as opposed to no lights and sirens, although may have arrived to its destination significantly faster, the time saved may not have had any clinical significance for majority of the cases (review of [10-13]). Gormley et al.  study on emergency service vehicles (ESV) collisions in Dublin, Ireland, showed similar results when operating under blue lights (similar to code-3). In Kahn et al.  11-year retrospective study, 60% of crashes and 58% of crash fatalities occurred during emergency use and compared to non-emergency use fatal crashes, emergency use fatal crashes occurred at intersections more often (p<0.001).
Figure 2: Warning lights and sirens use and collisions resulting in injury. Pie slices represent the percentage of collisions during warning lights and sirens (WLS) use versus other driving modes. Figure adapted from Custalow & Gravitz, 2004; Figure 4.