Diesel exhaust has caused acute irritant induced asthma following a single large exposure from a diesel railway engine. It has also acted as an adjuvant for sensitisation to aeroallergens. In vitro exposure to diesel exhaust results in release of IL-4 and histamine from basophils. Exposure to diesel exhaust particles at 200µg/m3, can cause sputum neutrophilia without changes in FEV1 in healthy volunteers. Exposure to 300µg/m3 in asthmatics however has resulted in a minor increase in methacholine reactivity.
Some of the highest exposures to diesel exhaust occur in bus garages in cold climates, where the buses are warmed up with running engines for some time before leaving. There have been growing concerns about adverse health effects of exposure to diesel exhaust. These include various effects on the respiratory system, cardiovascular and coagulation profile as well as possible carcinogenicity.
Three workers with occupational asthma with latency have been described working in bus garages where diesel exhaust was the most likely cause.