Long-term exposure to bushfire-related fine particulate matter and coronary plaque burden in asymptomatic adults

This study assessed the association between long-term exposure to bushfire-related fine particulate matter (PM2.5) and coronary plaque volume and components in asymptomatic adults.

A total of 365 community-based participants aged 40-70 years with a family history of coronary artery disease were included in this study and underwent serial coronary computed tomography angiography at baseline and three years later. Daily total and bushfire-related PM2.5 were estimated using validated models at 5 km spatial resolution and assigned by residential postcode, from which annual mean total PM2.5, bushfire smoke days and annual mean bushfire-related PM2.5 were derived. Mixed-effects linear regression was used to assess associations. The 10-year average annual total PM2.5 concentration was 5.88 µg/m3 in the period preceding baseline and 5.93 µg/m3 in the period preceding 3-year follow-up. Corresponding 10-year median cumulative bushfire-related PM2.5 concentrations were 6.06 µg/m3 (IQR, 5.18-6.80) and 6.43 µg/m3 (IQR, 5.67-7.26) for the periods before baseline and follow-up, respectively. A 1 µg/m3 increase in cumulative bushfire-related PM2.5 concentration was associated with increases in total plaque volume of 10.14 mm3 (95% CI: 1.45, 18.82) at baseline and 4.92 mm3 (95% CI: 1.33, 8.52) at 3-year follow-up. Exploratory analyses suggested weaker associations between PM2.5 exposure and plaque burden among statin users, although formal interaction testing was not statistically significant.

Long-term exposure to bushfire-related PM2.5 was associated with increased coronary plaque burden among asymptomatic adults with a family history of coronary artery disease, highlighting the need to reduce bushfire-related smoke exposure to mitigate adverse cardiovascular effects.