Effects of PM 2.5 from coal mine fire smoke on long-term incidence of major adverse cardiovascular events (MACE)

Abstract Background While coal mine fire smoke has been linked to short-term increases in cardiovascular events, there is little evidence on long-term risks. We investigated longer-term risk of major adverse cardiovascular events (MACE) following the 2014 Hazelwood coal mine fire in regional Victoria, Australia. Methods In this cohort study, combined administrative data on ambulance attendances, emergency department presentations, hospital admissions, and mortality from March 2014 to June 2022, with survey data from 2016/17. Time-location diaries for the mine-fire period were combined with modelled fire-related particulate matter ≤2.5µm in diameter (PM 2.5 ) to estimate individual exposures. We analysed the association between PM 2.5 exposure and time to MACE using a recurrent event survival analysis, adjusting for key confounders. Outcomes were examined over 8 years of follow-up and stratified by time. Results N = 2,725 cohort members agreed to linking their survey responses to administrative data. There was no detectable effect of fire-related PM 2.5 exposure on overall risk of MACE during 8-year follow-up. However, there was weak evidence suggesting increase in MACE risk in the first 3 years post-fire, with hazard ratios ranging from 1.05-1.18 per 10µg/m 3 of daily average PM 2.5 exposure. Nearly all analyses of cardiovascular death detected an increased risk across the entire follow-up period, with hazard ratios ranging from 1.19-1.25 per 10µg/m 3 . Conclusions We found smoke exposure predicted an increase in cardiovascular health service use in the three years after the mine fire. There was additional evidence that the mine fire increased risk of cardiovascular death over the entire 8-year follow-up. This suggests that cardiovascular screening should be a routine component of planning recovery after landscape fires.