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The purpose of this study was to explore components and
concentrations of motorcycle emissions in Taiwan. The driving
patterns of motorcycles in Taiwan were simulated in a
dynamometer. Samples of emissions were taken under idling,
acceleration, constant speed, and braking conditions. Total
hydrocarbon (THC), carbon monoxide, and nitrogen oxides were
analyzed with an automated instruments. Fifty-one volatile
organic compounds (VOCs) were analyzed with gas chromatography.
The effects of motor type (2 strokes or 4 strokes) and age on
motorcycle VOC emission profile were assessed. Emission factors
(EFs) were determined from emission concentrations; and ozone
production potentials of the various VOCs were also obtained
using maximum incremental reactivity (MIR) factors. The
results showed that the emission concentrations of in-use
motorcycles were much different from the newly produced
motorcycles. The EFs of two- and four- stroke new motorcycles
were 2.63, 3.28, 0.03 g/km and 6.68, 1.33, 0.52 g/km, for CO,
THC, and NOx, respectively. For in-used motorcycles, the EFs of
two- and four- strokes were 29.31, 18.18, 0.05 g/km, and 28.55,
2.48, and 0.33 g/km, for CO, THC, and NOx, respectively. Except
for the NOx concentrations and EFs of four-stroke motorcycles,
the concentrations and EFs of all other pollutants of in-used
motorcycles were all higher than the new ones. Among
different driving patterns, VOC concentrations were higher under
idling, constant speed at 50km/hr, and braking conditions than
under acceleration and constant speed at 30 km/hr conditions.
For four-stroke motorcycles, VOC concentrations of in-used
motorcycles were 17.1 times and 16.3 times of those of new
motorcycles for idling and braking conditions, respectively;
they were substantially different. The effects of total
mileage, catalyst, and gasoline on motorcycle VOC emission
profiles were also assessed. It showed that motorcycles using
leaded gasoline had higher VOC concentrations and EFs. Moreover,
comparing the concentrations and EFs of new and in-used
motorcycles, the results showed that total mileage and catalyst
usage.did play a role; however, other factors might also affect
the results. The mean ozone production potentials of two-
and four- stroke new motorcycles were about 2.86g/km and 0.73 g/
km, respectively, and those for two- and four- stroke in-used
motorcycles were approximately 3.49 g/km and 2.94 g/km,
respectively. It was obvious that the contribution of ozone
production from 2-stoke motorcycles was higher than four-stroke
ones. The mean ozone production potentials of new motorcycles
was 1.80 g/km, while that of in-used ones was about 3.22 g/km.
Thus, in-used motorcycles had higher potentials for ozone
production.
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