Air pollution is a global environmental and health concern, contributing to onset and deterioration of respiratory and cardiovascular diseases. As climate change and dependence on diminishing fossil fuel supplies have taken center stage in political and scientific debates, renewable carbon-neutral fuels like biodiesel receive increasing attention. The most common biodiesel within the European Union, rapeseed oil methyl ester (RME) is perceived to be a "green fuel", as it is sustainable and of biological origin, and therefore is often predicted to be less harmful to human health. Whilst replacing petrodiesel with biodiesel may have advantageous ecological impacts, consequences to respiratory health remained largely unexplored.