Background: Exposure to diesel exhaust causes inflammatory responses. Previous controlled exposure studies at a concentration of 300 μg/m(3) of diesel exhaust particles mainly lasted for 1 h. We prolonged the exposure period and investigated how quickly diesel exhaust can induce respiratory and systemic effects.
Methods: Eighteen healthy volunteers were exposed twice to diluted diesel exhaust (PM1 ~300 μg/m(3)) and twice to filtered air (PM1 ~2 μg/m(3)) for 3 h, seated, in a chamber with a double-blind set-up. Immediately before and after exposure, we performed a medical examination, spirometry, rhinometry, nasal lavage and blood sampling. Nasal lavage and blood samples were collected again 20 h post-exposure. Symptom scores and peak expiratory flow (PEF) were assessed before exposure, and at 15, 75, and 135 min of exposure.
Results: Self-rated throat irritation was higher during diesel exhaust than filtered air exposure. Clinical signs of irritation in the upper airways were also significantly more common after diesel exhaust exposure (odds ratio = 3.2, p<0.01). PEF increased during filtered air, but decreased during diesel exhaust exposure, with a statistically significant difference at 75 min (+4 L/min vs. -10 L/min, p = 0.005). Monocyte and total leukocyte counts in peripheral blood were higher after exposure to diesel exhaust than filtered air 20 h post-exposure, and a trend (p = 0.07) towards increased serum IL-6 concentrations was also observed 20 h post-exposure.
Conclusions: Diesel exhaust induced acute adverse effects such as symptoms and signs of irritation, decreased PEF, inflammatory markers in healthy volunteers. The effects were first seen at 75 min of exposure.