Effects of threat and efficacy messages on expected adherence to decontamination protocols in an immersive simulated chemical incident: A randomized controlled experiment

The UK’s Initial Operational Response (IOR) decontamination protocol requires that chemically contaminated casualties remove contaminated clothing (disrobe) and then apply water or absorbent materials to skin. The health-protective efficacy of the protocol is predicated on casualties quickly accepting both the need to act and the fact that this protocol is an effective action. The aim of this study was to test whether adherence is affected by the presentation of information by first responders about the severity and likelihood of contamination (Threat) and the health-protective efficacy of IOR procedures (efficacy). A double-blind randomized controlled experiment (N = 132) with a 3x2 independent measures design (registration number: ISRCTN17886859) was used to assess the effects of threat and efficacy on behavioural expectations during a simulated chemical incident, presented as an immersive video. Results indicated that addressing the threat of contamination made participants more likely to expect themselves to disrobe were the situation real. Emphasizing the efficacy of protective action made participants more likely to expect themselves to apply absorbent materials to skin and had an indirect positive effect on disrobing expectations, mediated by efficacy perceptions. We recommend that first responders explicitly address the threat of contamination and efficacy of decontamination when communicating with chemically contaminated casualties.