Using Transit Vehicles as Probes to Monitor Community Air Quality and Exposure

Abstract

This project evaluates the feasibility of using transit vehicles traveling on fixed routes for near-road exposure assessment. Continuous on-road measurements of four pollutants (PM2.5, PM10, NO2, and O3) were recorded in conjunction with GPS locations. The data can be used to quantify exposures experienced by pedestrians, passengers, bus users, and near-road residents.

Concurrent near-road measurements were used to verify and provide associations with the on-road data. The study tests two hypotheses: 1) Community exposures to transportation pollutants can be represented by short-term spatio-temporal measurements using on-road air monitors; and 2) near-road receptors are not affected by the traffic emissions from surface street emissions and can be represented by onroad air monitors. The objectives of this study were to 1) provide reliable exposure concentration estimates for a community using transit vehicles equipped with mobile air monitors, and 2) evaluate associations of short-term transportation related air pollutant (TRAP) concentrations with hourly exposure concentrations for near-road communities.

Mobile monitoring was conducted along two designated routes around the UTEP campus shown in Figure 1, with UTEP researchers driving at a speed of less than 30 miles per hour. In both routes, a detour is made on Schuster Avenue to take the mobile monitoring station (Figure 2) closer to the CAMS 12 site, which is located approximately 50 ft off Rim Road, so that a comparison could be made between the air pollutant data collected by the mobile monitoring station’s instruments and CAMS 12 FRM data. In addition, a fixed site with the same air quality monitoring instruments was installed on Sun Bowl Drive to provide another location for data comparison. Each trip lasted about 12-15 minutes including stop-and-go at all traffic intersections.

The air monitoring campaign made a total of 282 trips (170 outer loops and 112 inner loops) and collected PM2.5, PM10, NO2, O3, and GPS data every second. Data were analyzed in conjunction with the fixed station data.