Sociodemographic circumstances, health, and life experience shape posttraumatic distress trajectories among individuals exposed to smoke during a large-scale coal mine fire

The 2014 Hazelwood coal mine fire in the Latrobe Valley, Australia, distributed toxic smoke into surrounding communities over 45 days. This study investigated risk and protective factors associated with four trajectories of posttraumatic distress (resilient, recovery, delayed-onset, chronic) among exposed adults. Participants (N = 709) completed surveys in 2016–2017 and 2019–2020 assessing mine fire–related particulate matter (PM_2.5) exposure; sociodemographic, physical, and mental health variables; and exposure to other traumatic and recent stressful events. Mine fire–related posttraumatic distress was measured using the IES-R; trajectories were determined according to established clinical significance thresholds. Relative risk ratios (RRRs) were generated from multivariate multinomial regressions. The resilient trajectory was most common (77.0%). The chronic trajectory (8.5%) was associated with loneliness, RRR = 2.59, 95% CI [1.30, 5.16], and physical health diagnoses, RRR = 2.31, 95% CI [1.32, 4.02]. The delayed-onset trajectory (9.1%) was associated with multiple recent stressful events, RRR = 2.51, 95% CI [1.37, 4.59]; mental health diagnoses, RRR = 2.30, 95% CI [1.25, 4.24]; loneliness, RRR = 2.05, 95% CI [1.09, 3.88]; and male gender, RRR = 2.01, 95% CI [1.18, 3.44]. Socioeconomic advantage protected against chronic, RRR = 0.68, 95% CI [0.53, 0.86], and delayed-onset trajectory membership, RRR = 0.68, 95% CI [0.50, 0.94]; social support protected against chronic trajectory membership, RRR = 0.67, 95% CI [0.49, 0.92]. PM_2.5 exposure did not determine trajectory. These findings enhance understanding of longer-term posttraumatic responses to large-scale smoke events and can inform mental health initiatives within at-risk communities.