(I)The cleaning operation began on March 2, 2020 and, based on the statistics until December 15, 2020, the street washing operation reached 17,113.3 kilometers. The cumulative achievement rate was 100%.
(II)Estimation of the street cleaning benefits in pollution reduction:
The total length of the sweeping street in this period was 17,113.3 kilometers. According to the EPA's reduction formula (reduction amount = length of sweeping street × reduction factor), total suspended particle (TSP) can be reduced to 236.16 metric tons, 44.49 metric tons of PM10 and 10.39 metric tons of PM2.5. In addition, according to the 2020 Air Pollution Control Plan of Chiayi City, the control category of the project is classified as “fugitive emission source”, which adopts a control strategy of “Strengthening Street Dust Cleaning Operation” with the reduction planning method of “Execution Street Cleaning Operation” (including the cleaning team work of the bureau). It is scheduled to perform a total cleaning length of 68,000 km, which is expected to reduce TSP 938.4 metric tons, PM10 176.8 metric tons and PM2.5 41.2 metric tons. The implementation of this project long with the EPA cleaning team (until December 15 statistically) with the results of a total of 68,276.1 km of washing length, is expected to reduce TSP 942.21 metric tons, PM10 177.51 metric tons and PM2.5 41.44 metric tons, having reached 100% of estimated objective.
(III)Census of road fouling condition:
In order to strengthen the mastery and improvement of the road dirt level in Chiayi City to serve as a reference for regular planning of the street washing route, the project had conducted a comprehensive road census on Chiayi City's roads and streets washing operation every month. Road census work began in February, and a totaled 374 time/road had been surveyed by the end of December. The total number of kilometers in the census reached 871.75 kilometers. The results of the census accounted for more than 89% of Class A roads in December and 11% of Class B roads. The 34 cases (roads) were reported to have improved.
(IV)Inspection to the field operation of street washing:
The road inspection was carried out three times a week. The statistics of this year were up to December. Investigation to the street washing operation had been conducted for 126 times, the total inspection length has reached 1,345.9 km.
(V)Performance evaluation for the street flushing:
The performance of reduction in the street flushing and establish the road emission coefficients of the city, 20 spots were selected on 16 roads and streets in the street cleaning project for street dust load testing and sample analysis before and after the flushing. Before the street flushing, the average street dust load was 1.71g/m2 and silt load 0.81g/m2; the average road class was classified as Class B according to the street dust load control target of EPA. After the street flushing, on the other hand, the average street dust load dropped to 0.35 g/m2 and silt load 0.16g/m2; therefore the average road class was improved to Class A, and average street dust reduction 79% as calculated, indicating that the street dust loads across the city decreased effectively thanks to the regular flushing of dusty streets.
(VI)Recommendations for policy control or administrative implementation：
(1)Emergency response measures against air quality deterioration，adding a second street washing vehicle, when AQI ≥ 151, reduce the vehicle speed to below 15km /hr。
(2)When the "orange light" warning is issued for the high temperature in high summer, the street washing vehicle will be activated from 11 to 14 o'clock to reduce the temperature, reduce heat injury incidents and reduce street dust.
