The underlying mechanisms governing the dispersion of the air and noise pollution
differ significantly. However, regardless of meteorological and traffic conditions,
a direct comparison of the two pressures was ensured in our case study, since sampling
was always carried out simultaneously. Significant between-mode variations, especially
in air pollution exposure were observed over the 12-month sampling period
(Table 1). Regarding the annual average exposure levels, the motorcyclist was observed
to have the highest exposure, followed by in-vehicle pollution. Pedestrians
and bicyclists seem to consistently have the lowest exposure. Average exposure concentration
levels experienced on the motorcyclist were 2 to 3 times higher than
those on the car passenger. The motorcyclists reported that they felt exhaust gases,
but also motorcycle petrol fumes in their breathing zone in “rev-up” conditions. This
is most probably the reason for an annual average VOC exposure level of approximately
300 ppb compared to 100 ppb in-vehicle pollution (3 to 1 relation). Regarding CO
and estimated benzene exposure motorcycle/vehicle analogy is approximately 3 to 2.
The high mean VOC and CO exposure of car passengers compared to pedestrians and
bicyclists is definitely due to their road position, located closest to the source of the
majority of air emissions, i.e. within the traffic lanes close to car exhausts. Average exposure
levels for all pollutants under consideration expe