It is indisputable that transportation is one of the potential sources of urban air pollution. The pollutants
related to transportation that causes air pollution include Nitrogen Oxides, Ozone, Carbon Monoxide and
Sulfur Dioxide. Other important emissions generated by transportation and directly affect air quality in
Bangkok are PM10, TSP, and Lead. The Pollution Control Department has regular monitoring activities to
assess the extent of those pollutants. The records during the last ten years indicate gradual decrease in
concentration as discussed below.