The San Joaquin Valley is identified as an area with a high level of particulate matter (PM) in the air, reaching above the federal and state clean air standards (EPA 2019). Many of the cities in the valley are classified as the most polluted cities in the United States for both particulate matter and ozone pollution (American Lung Association, 2021). To resolve this issue, alternative forms of transportation have been considered in transportation planning. In this study, active transportation mode air quality was monitored on selected Woodward Park and Old Clovis trails and urban bike lanes. Real-time aerosol monitors, and low-cost sensors were carried in a backpack on bicycles during the sampling. Researchers collected GPS data via a portable GPS technology called Tracksticks. Driving transportation mode air quality data was acquired from the roadways within the Fresno/Clovis area, spanning six sampling routes, and during intercity trips between Fresno, Berkeley, and Los Angeles, for a total of five sampling routes. ‘On-Road' (outside vehicle) monitors were installed on the roof of a vehicle while ‘In-Vehicle’ monitors were installed inside the vehicle for comparison with the particulate pollution levels in the two contrasting microenvironments. The results showed the following three main outcomes: (1) clear relationships exist among PMs of different sizes; (2) there were greater variations in air quality of bike trails and On-Road samples than backyard and In-Vehicle samples; (3) we observed significant differences in air quality inside and outside the vehicle while driving local and intercity roadways; and (4) the road trip to the Bay area revealed that San Joaquin Valley has increased ambient PM2.5 and black carbon (BC) levels compared to those in the Bay Area on every trip, regardless of the daily change of the air quality.

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Publication Type



Active Transportation, Sustainable Transportation and Land Use

Digital Object Identifier


MTI Project



Air Pollution, Built Environment, Environmental Monitoring, Nonmotorized Transportation, Public Health


Infrastructure | Transportation