Comparing particulate morphology generated from human- made cellulosic fuels to natural vegetative fuels

Background. In wildland–urban interface (WUI) fires, particulates from the combustion of both natural vegetative fuels and engineered cellulosic fuels may have deleterious effects on the environ- ment.

Aims. The research was conducted to investigate the morphology of the particulate samples generated from the combustion of oriented strand board (OSB). Findings were compared to the particulate samples collected from the combustion of noble-fir branches.

Methods. The exposure conditions were varied to induce either smouldering combustion or flaming combustion of the specimens. Particulate samples were collected using thermophoretic sampling. Scanning electron microscopy (SEM) and subsequent image analysis were used to characterise particle sizes.

Key results. The morphology of the generated particulates was influenced by the state of combustion for OSB as well as noble-fir branches.

Conclusions. The combustion state resulted in differences in the particulate morphology for both OSB and noble-fir branches. More than 85% of the analysed particle diameters were less than 1000 nm in size collected from OSB specimens during smouldering combustion.

Implications. The findings are the first step to better quantifying the morphology of particulates generated during WUI fire outbreaks. The experimental protocols and analysis methods presented may shed light on a problem that impacts human health in the WUI.