Background. While pre-trauma personality and mental health measures are risk factors for post-traumatic stress disorder (PTSD), such information is usually obtained following the trauma and can be influenced by post-trauma distress. We used data collected from a community-based survey of young adults before and after a major natural disaster to examine the extent to which participants' traumatic experiences, demographic and pre-trauma risk factors were associated with their screening positive for PTSD when re-interviewed.

Method. A representative selection of 2085 young adults from the Australian Capital Territory and environs, interviewed in 1999 as part of a longitudinal community-based survey, were re-interviewed 3–18 months after a major bushfire had occurred in the region. When re-interviewed, they were asked about their experiences of trauma threat, uncontrollable and controllable traumatic experiences and their reaction to the fire. They were also screened for symptoms of fire-related PTSD experienced in the week prior to interview.

Results. Four-fifths of participants were exposed to the trauma with around 50% reporting having experienced uncontrollable traumatic events. Reporting PTSD symptoms was associated with being female, having less education, poorer mental health and higher levels of neuroticism prior to the trauma. Particular fire experiences, including being evacuated and feeling very distressed during the disaster, were more strongly associated with PTSD symptoms compared with pre-trauma measures.

Conclusions. While demographic and pre-trauma mental health increased the likelihood of reporting PTSD symptoms, exposure to trauma threat and reaction to the trauma made greater contributions in explaining such symptoms as a result of this disaster.