Evaluating Emissions from Select Urban Parking Garages in Cincinnati, OH, Using Portable Sensors and Their Potentials for Sustainability Improvement

Urban parking around the world faces similar challenges of inadequate space, pollution, and carbon emissions. Although various smart parking technologies have been tested and implemented, they primarily aim to reduce the time spent searching for parking, without considering the impact on air quality. In this study, the air quality in three urban garages was investigated with portable instruments at the entrance and exit gates and inside the garages. Garage emissions measured include CO 2 , PM 2.5 , PM 10 , NO 2 , and total VOCs. The results suggested that the PM 2.5 levels in these garages tend to be higher than the ambient levels. The emissions also exhibit seasonal variations, with the highest concentrations occurring in the summer, which are 20.32 µg/m 3 in Campus Green, 14.25 µg/m 3 in CCM, and 15.23 µg/m 3 in Washington Park garages, respectively. PM 2.5 measured from these garages is strongly correlated (with an R 2 of 0.64) with ambient levels. CO 2 emissions are higher than ambient levels but within the indoor air quality limit. This suggests that urban garages in Cincinnati tend to enrich ambient air concentrations, which can affect garage users and garage attendants. Portable sensors are capable of long-term emission monitoring and are compatible with other technologies in smart garage development. With portable air sensors becoming increasingly accessible and affordable, there is an opportunity to integrate these devices with smart garage management systems to enhance the sustainability of parking garages.