Exposure to particulate matter when commuting in the urban area of Grenoble, France

Air pollution is a major cause of mortality and chronic diseases worldwide, with particulate matter (PM) being the primary contributor to this burden. Few studies have yet been carried out on the effect of modes of transport, times of day or travel locations on the exposure of individuals to PM. We conducted an experiment in Grenoble, France, in spring 2022 to study factors determining the individual exposure to PM. Using low-cost sensors (LCS), PM₁ (PM < 1 μm) and PM_2.5 (PM < 2.5 μm) levels were measured in four transport modes (bike, walk, bus, and tramway), across four different streets and at three different times of the day. Findings are: (i) - the mode of transport plays a more important role on levels of PM_ratios (PM concentration ratio to reference) than the time of the day or the location, (ii) - PM_ratios and inhalation doses are higher in active modes of transport (bike, walk) than in passive ones (bus, tram), (iii) – levels of exposure to PM are ranked as: tram < bus < walk < bike, and (iv) – a statistical model has been developed to predict PM_ratios as a function of transport mode, travel period, street ratio, and traffic. Exposures to PM in trams are found 12%–25% and 13%–20% lower than in passive modes of transport for PM₁ and PM_2.5, respectively. Wearing LCSs makes it possible to estimate commuters' exposure to PM and their use should be encouraged for prevention purposes.