Thursday, May 19

Health. Pollution: are pedestrians and cyclists the most exposed?

“Cyclists and pedestrians inhale more particles produced by road traffic than users of motorized transport. This is the name of a study conducted by researchers from Inserm (National Institute for Health and Medical Research) and the Pierre Louis Institute of Epidemiology and Public Health, published on the website magazine website Environment International.

The study is based on the analysis of soot carbon, “considered as one of the best markers of road traffic” and “generated by the incomplete combustion of fossil fuels and other molecules produced by road traffic”, detail the authors of this study supervised by Basile Chaix, director of research at Inserm.

The influence of physical activity and ventilation

For the study, the researchers therefore followed 283 participants, for 6 days, in Greater Paris (between 2018 and 2020). Users of different types of transport, equipped with soot carbon sensors. The aim was not only to take into account the quantity of pollutants in the air, but the “real” exposure to black carbon, subject to more or less significant variations depending on the type of transport. This is due to “minute ventilation”: the flow corresponding to the lung volume mobilized in one minute by breathing. For example, a cyclist consumes more air, due to physical activity, than a motorist.

“Although less exposed in terms of soot carbon concentrations than users of motorized transport, pedestrians and cyclists inhale more of this pollutant for an equivalent journey time”

What emerges from this study is that the volume of air absorbed increases with the intensity of physical activity. This explains why it is cyclists first, then pedestrians, who inhale the most soot carbon, for an equivalent journey. They are therefore more subject to pollution than public transport users or motorists. And so it is the last two types of users mentioned who are surrounded by the air most polluted by soot carbon.

Walking and cycling, beneficial activities

However, the authors of the study want to put things into perspective: there is no question of pleading to abandon walking and cycling, which are suggested in particular for good health.

“However, it is important to clarify that the inhalation of air pollutants is only one element of the picture of benefits and risks associated with the different modes of transport, and that the other pieces of the puzzle which are the exposure to noise, stress in transport and the physical activity carried out, for which the practice of walking and cycling is widely recommended”, explains Basile Chaix, research director at Inserm and co-author of the study. .

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