Short-term Exposure to Nanoparticle-rich Diesel Engine Exhaust Causes Changes in Brain Activity but not in Cognitive Performance in Human Volunteers.

In previous studies we showed that short-term exposure to high (300 μg/m3) concentrations of diesel engine exhaust (DE) caused an increase in the high-frequency part of the brain spectrum (measured by electroencephalography, EEG). The purpose of this study was to investigate the same markers at lower, more commonly occurring concentrations of DE (100 μg/m3) and to investigate the effects of diesel exposure on cognitive performance. We exposed 12 healthy volunteers to dilute DE (particle concentration: 100 µg/m3) and filtered purified air for one hour using a double blind randomized crossover design. Brain activity of the frontal cortex was monitored before, during and 0, 1, 4 and 24 hours following exposure using quantitative electroencephalography (QEEG). Fast Fourier Transforms were used to calculate the amplitudes of pre-defined frequency bands in the spectrum of the QEEG. Cognitive performance was assessed at baseline and at 0 and 24 hrs by two tests focusing on acute memory and information processing. The data demonstrate a slow response to DE in the frontal cortex characterized by an increase in fast wave activity (beta 1, beta 2) which became significant between 1 and 4 hrs after exposure. Acute effects on cognitive function were not observed. Neither the memory task nor the attention task was affected during and after exposure to DE. Conclusion. This study confirms our earlier findings on effect of diesel exhaust on brain function with regard to the type of interaction (fast-wave activity in EEG) and shows that the effect continues up to 4 hours after exposure. A possible relationship between these EEG findings and cognitive functions could not be established.