The World Health Organsiation (WHO) has reclassified diesel fumes as a Categerory 1 carcinogen, similar to tobacco. The primary risk is that of lung cancer, but there may be a link to bladder cancer. This has resulted in a spate of enquiries about measuring diesel fumes.
Diesel exhaust fumes are a complex mixture of particulate and gaseous pollutants. The highly respirable particles consist mainly of a carbonaceous core and adsorbed organic compounds. The most important adsorbed organics are n-alkanes and polycyclic aromatic hydrocarbons (PAHs). Oxides of nitrogen in the exhaust gas may react with PAHs to form highly carcinogenic nitro-PAHs.
Because diesel fumes are complex, it is not straightforward to measure fumes. The current best practice is to measure elemental carbon. This can be done using cassettes and a sampling pump with subsequent laboratory analysis.
However, there is nothing with which to compare any results. There is no WEL or any other figure. So we can get a set of results and not know if they are good or bad.