Concerning the aerosol pollution in metropolitan areas, vehicle dust is the primary culprit for it. In fact, the effect will not be very significant if we just rely on containing stationary sources of pollution. Therefore, street washing operation needs to be applied in order to decrease aerosol pollution. Intending to decrease road dust volume and to keep streets clean in the City so that the air quality of the City will not be getting worse day by day, Chiayi City EPB report to EPA for fund assistance in “Chiayi City Street Washing Project” (The Project hereafter), which may help to get to the objectives to clean up city streets and improve air quality by means of street washing operations. This report is one of the 2006 year end reports. The project duration spanned from January to December 31, 2006. There were 14 primary and secondary roads in the urban area of the city targeted to be washed. EPA authorized totally a length of 12,000km of streets that have to go through street washing in the year. The achievement statistics of street washing from January to December 31, 2006 indicates that there was a length of 12,566.3 km has been undertaken by the street washing project； the achievement ratio is 104.7% in total. The average street washing speed was about 13.5km/hr. The average monthly used water volume per kilometer was between 1.18-1.21 ton with an average of 1.19 ton per kilometer. There were seven sampling analysis for street washing water quality in this year till December 31. The results have shown that the control standard has been met for the retrieved water to be used in containing dust, (though the standard was abolished in October this year.) This Project is being held in accordance to TSP and PM tests. After compilation and analysis of these test results in years, positive correlation between street washing operation and the decrease rate in TSP and PM tests has been revealed. That means street washing operation indeed can reduce the aerosol quantity in the air. However, there are many factors that will influence the air quality. If other variables have not been prevented (especially climate factors and background density), there will be factual difficulties to realize how a street washing operation can reflect the reduce rate in a certain road section. But generally speaking, the street washing effect can maintain equal reduce rate as same as that of next day. It does indicate that this project is necessary after all. The result of the questionnaire appears that it is acceptable for Chiayi residents in terms of air quality and street dust with expectation that they will be approved somehow. As for street washing operation itself, people maintain more than 90% affirmative attitude. It tells that this project is necessarily to be executed continuously.

2006,Chiayi City,Street Fugitive Dust Improvement,Street Washing