SUCCESS OF FUEL QUALITY IMPROVING POLICY IN REDUCING BENZENE AIR CONCENTRATIONS IN BANGKOK

Abstract

The Thai’s policy in improving of fuel quality to the changing of emissions and
concentrations of air pollutants in Bangkok is evaluated in this study. Benzene content in gasoline had been
decreased from 3.5% (EURO II standard) to less than 1.0% (EURO IV standard) since the year 2012. The
IVE (International Vehicle Emission) model was applied to develop emission factor of benzene taking into
consideration actual fleets and characteristics of vehicles in Bangkok. These vehicles consisted of passenger
car, motorcycle, van and pick up, taxi, bus and truck. Then, emission inventory of benzene emitted from
mobile sources was calculated. It was found that about 83% of total emissions of benzene were contributed
from motorcycle (43%) and passenger car (40%). Emission amounts were reduced from 1.32 x 103
ton/year
to 0.57 x 103
ton/year as resulted from changing of fuel quality from EURO II to EURO IV standard.
AERMOD dispersion model was used to simulate ambient ground level concentration of benzene prior and
after implementing this policy. Results revealed significantly reduction of benzene concentrations in
Bangkok’s environment. Spatial distribution of benzene pollution map illustrated that areas having annual
concentration higher than 1.7 g/m3
(the Thai’s air quality standard for benzene) were still only found in
traffic-congested zone of the central business district in the metropolitan area.