Effects of hydrogenated vegetable oil (HVO) and HVO/biodiesel blends on the physicochemical and toxicological properties of emissions from an off-road heavy-duty diesel engine

•HVO showed NOx reductions, but increased with biodiesel blending.•The absence of sulfur and aromatics led to PM and particle number reductions.•PAH emissions were lower for the biofuels and further decreased with higher biodiesel blending.•All fuels induced oxidative stress, with the biofuels leading to reduced oxidative stress in PM.•DTT activity and cytotoxicity correlated with PM and particle-phase PAHs. In this study, the regulated emissions, gaseous toxics, and the physical, chemical, and toxicological properties of particulate matter (PM) emissions from a legacy off-road diesel engine operated on hydrogenated vegetable oil (HVO) and HVO blends with biodiesel were investigated. This is one of the very few studies currently available examining the emissions and potential health effects of HVO and its blends with biodiesel from diesel engines. Extended testing was conducted over the nonroad transient cycle (NRTC) and the 5-mode D2 ISO 8718 cycle. Nitrogen oxide (NOx) emissions showed statistically significant reductions for HVO compared to diesel, whereas the biodiesel blends statistically significant increases in NOx emissions. PM and solid particle number reductions with pure HVO and the biodiesel blends were also observed. Low-molecular weight polycyclic aromatic hydrocarbons (PAHs) were the dominant species in the exhaust for all fuels, with pure HVO and the biodiesel blends showing lower concentrations of these pollutants compared to diesel fuel. Our results showed that the oxidative stress and cytotoxicity in PM emissions decreased with the use of biofuels. Notable correlations were observed between PM emissions and oxidative stress and cytotoxicity, especially elemental carbon and particle-phase PAH emissions.