In the major tunnels, transit-average in-vehicle NO2 concentrations were lower than outside-vehicle concentrations for all vehicles with cabin air recirculation either on or off.
There is a lack of knowledge regarding in-vehicle concentrations of nitrogen dioxide (NO2) during transit through road tunnels in urban environments.
Finally, the highest in-vehicle concentrations (148.0 · 103 173.0 · 103 particles/cm3) were measured in central commercial areas of Athens during, on average, 55 min drives.
In fact, such full-stop queues are rare events, while in most cases congestion waves propagate through the traffic stream, so that on a bridge there are periodically times of closely-spaced vehicle concentrations and times of flowing traffic, where vehicles are more distant.
Vehicle concentrations tested were therefore 0.1% albumin and 0.0789, 0.789 and 7.89 μM ethanol.
In addition, while we have included the effects of emissions on ambient concentrations, we have not captured the effects on in-vehicle concentrations and personal exposures.
Other studies have found significant increases in indoor and in-vehicle concentrations of many pollutants, including fine particles, compared to measurements taken at nearby outdoor monitoring stations.
Based on previous results (Upham et al. 1996, 1998), 1-methylanthracene as well as PFOA were used as positive controls of inhibition of GJIC, whereas acetonitrile at vehicle concentrations was used as a negative control.
Ambient NOx measurements are likely to be a poor reflection of roadway or in-cabin vehicle concentrations owing to the rapid transformation of emissions with distance from the roadway.
We could not quantify this pathway, given challenges in linking epidemiological evidence from central site monitors with personal exposures during commuting, as well as because of complications related to differences between ambient and in-vehicle concentrations, but we anticipate that this pathway would be appreciable enough to merit consideration in future analyses.
