Exposure to particulate air pollution has been shown to increase cardiovascular mortality and morbidity, and in previous controlled exposure studies has been shown to have acute cardiovascular and respiratory effects. The last decade has seen an unprecedented drive towards finding a bioeconomical and renewable source of fuel in order to reduce our dependence on fossil fuels. Although both biodiesel and bioethanol have emerged as contenders for future fuels, biodiesel remains as the strongest contender within European markets. In 2007 researchers at the EPA released a commentary, which concluded that the assumed correlation between the chemical composition of biodiesel exhaust and a reduction in health effects was only hypothetical. They suggested that there was a clear need for the study of health effects in humans regarding biofuel exhaust. In this project the investigators aim to investigate the cardiovascular, respiratory and inflammatory responses to biofuel exhaust exposure in healthy volunteers.