There is currently no OEL for diesel fumes in the UK. This study reports parallel measurements of airborne levels of diesel fume pollutants in nine distribution depots where diesel powered fork-lift trucks (FLTs) were in use. Correlations between individual pollutants are assessed as well as their spatial distribution. Samples were collected on board FLTs and at background positions at nine distribution depots. Substances measured and the range of exposures by site were: respirable dust (n = 76) GM </= 80-179 micro g/m(3); elemental carbon (n = 79) GM = 7-55 micro g/m(3); organic carbon (n = 79) GM = 11-69 micro g/m(3); ultrafine particles (n = 17) range = 58-231 x 10(3) particles/cm(3); selected particulate phase polycyclic aromatic hydrocarbons (PAHs) (n = 14) range = 6-37 ng/m(3). In addition, a tracer method based on ultrafine particle measurements was used to estimate the spatial distribution of total carbon and PAHs at the sites monitored. The spatial distribution was found to be reasonably uniform. Major diesel fume aerosol components were, in general, well correlated (r = 0.62-0.97). CO(2) measurements were also made and found to be below the HSE guideline of 1000 p.p.m., with most levels below 600 p.p.m.