Background

Air pollution is a crucial issue for residents' health in urban areas. Many sources may cause air pollution such as sandstorm , industrial emission, or motor vehicles. Taipei city is the capital of Taiwan with more than 2.5 million population. The main source of air pollution comes from 1.8 million registered motor vehicles and additional vehicles from nearby townships. The monitoring and warming system becomes the most urgent service by the city government. The Taiwan Environmental Protection Agency (EPA) has implemented 60 air quality monitoring stations in the whole island (http://taqm.epa.gov.tw/taqm/tw/default.aspx). However, there are only 6 stations locate in Taipei city. In consequence, residents in Taipei do not have sufficient information to escape from air pollution in commuting.

Method

An alternative monitoring system was developed in this study. This study employs the emerging GIS (geographic information system) LBS (location-based service) technology to incorporate real-time traffic data provided by the Department of Transportation, Taipei City Government. The carbon monoxide emission for each street segment is calculated from the data (http://teds.epa.gov.tw/new_main1-2.htm). Then, the emission is translated to pollution concentration based on the concept of street canyon (Qin and Kot, 1993; Barrefors, 1996). The spatial estimation of the pollution concentration from motor vehicle is verified by comparing with the 6 EPA monitoring stations. Finally, an Android-based mobile application (APP) is developed to provide real-time alert when walking or driving in an air-polluted area.

Result

The estimated pollution concentration data is compared with monitoring data on hourly basis in terms of weekday and weekend. Fig 1 and Fig 2 show the results of Station VELJA00 for weekday and weekend respectively as an example. Results show a slightly systematic difference between estimated and monitoring data. The maximun difference for weekday and weekend is 0.55 ppm and 0.56 ppm respectively. This difference can be attributed to the ignorance of micro climate.

A location-based real time air quality alert system is developed. An air quality map will show on screen with different colors indicating different pollution levels. In addition, The APP will give a sound warning when approaching a 100-meter buffer zone of a polluted street segment (Fig. 3).

Fig. 1 comparison for weekday data      Fig.2 comparison for weekend data

Fig. 3 a LBS real time air quality APP

Reference

Barrefors, G. (1996) Air pollutants in road tunnels. Science of The Total Environment, 189–190: 431-435.

Qin, Y. and Kot, S. C. (1993) Dispersion of vehicular emission in street canyons, Guangzhou City, South China (P.R.C.). Atmospheric Environment. Part B. Urban Atmosphere, 27(3): 283-291.