Atlas de l'exposition aux pollutions atmosphérique et sonore

Methodology

Participants and trips made

More than 90 trips were made during the month of June 2016 by eight INRS urban studies students and a professor in charge of the project. Three teams of three people each were formed: the first travelled by bicycle, the second by public transit, and the third by car. The trips were made from a peripheral Montreal neighbourhood to the downtown area at 8 am, and, in the opposite direction, at 5 pm. These trips represent more than 60 hours of travel and 1,000 km collected on the Island of Montreal.
The destinations selected downtown are either centres of higher education—Concordia University, INRS Urbanisation Culture Société, McGill University and UQAM (Université du Québec à Montréal)—or important employment centres such as the Stock Exchange Tower and Complexe Guy-Favreau (government services and shopping complex). The origins of the trips correspond to the intersection of two residential streets in outlying Montreal boroughs, and, in particular, Ahuntsic-Cartierville, Rosemont–La Petite-Patrie, Montréal-Nord, Verdun, Saint-Laurent, etc.
 

Measuring noise and pollution

Three measuring devices were used: 1) a personal noise dosimeter (Brüel & Kjaer); 2) an air quality monitor with an (NO2)sensor (Aeroqual); and 3) a GPS sportswatch (Garmin 910 XT). These devices enabled us to measure the individuals’ exposure to air pollution (NO2) and noise (dB(A)), as well as their heart rates, and to obtain a GPS trace of the trip.

Photo credits : Gophrette Power.
 

Measuring the inhaled dose of the nitrogen dioxide (NO2) pollutant

Due to their higher physical activity levels than car and public transit users, cyclists have higher ventilation rates. In other words, they breathe more litres of air per minute into their lungs and thus inhale more air pollutants. So it is appropriate to compare inhaled doses with the three modes of transport by considering this ventilation parameter. For example, some earlier studies showed that although car users’ levels of exposure are higher than cyclists’, the latter inhale more pollutants.

In order to accurately estimate ventilation and the inhaled dose of NO2 throughout the trips, each participant performed a progressive and maximal effort test in the Physical activity and health lab (LAPS) headed by Marie-Ève Mathieu at the University of Montreal. A personalized equation linking heart and ventilation rates was then obtained for each participant. This equation was used to estimate ventilation during the trips based on the heart rate as measured by the Garmin watch. Finally, by simply multiplying the estimated ventilation (litres per minute) and the value for NO2 pollution measured by the Aeroqual sensor, it is possible to relatively accurately estimate the inhaled dose in real time.


 

Photo credits : Physical activity and health lab (LAPS).