Early life exposure to coal mine fire and tobacco smoke affect subclinical vascular function

Objective To evaluate whether vascular health in young children was associated with exposure to a 6-week episode of coal mine fire smoke or environmental tobacco smoke (ETS) in a retrospective cohort study. Methods Three years after a coal mine fire in Victoria, Australia, we investigated the vascular health of children either in utero (n=75) or aged <2 years (postnatal exposure, n=96) at the time of the fire. The outcomes were the carotid intima-media thickness (IMT) and pulse wave velocity (PWV). The mean and peak daily particulate matter <2.5 mu m in diameter (PM2.5) exposures were estimated based on their daily locations throughout the fire period. Multivariable linear regression models were used to test for associations between the fire-related PM2.5 and outcomes adjusted for relevant covariates including ETS. Results In the postnatal-exposure group, each 10 mu g/m(3) increase in mean PM2.5 level was independently positively associated with PWV (beta=0.116, p=0.028). When these two groups were combined, there was an association between mean PM2.5 and increased PWV in those children who had ETS exposure (beta=0.148, p=0.033) or whose mothers smoked (beta=0.151, p=0.011), but not in those not exposed to ETS or maternal smoking. Conclusions Three years after a coal mine fire, infants aged up to 2 years at the time of exposure have increases in vascular stiffness. Although no adverse effects were observed in the in uterus exposure group, further follow-up study is needed to elucidate the long-term effects of coal mine fire smoke exposure.