Atlas de l'exposition aux pollutions atmosphérique et sonore



Noise is measured with a Brüel & Kjaer dosimeter (type 4448), which refers to an average measurement of noise in decibels (dB(A)) for each minute of the trip (LAeq 1 min). The World Health Organization (WHO) recommends that the 55 dB(A) outdoor noise guideline value not be exceeded during the day. In addition, the Secretariat of the Environment of Mexico City (Secretaría del Medio Ambiente) recommends that noise not exceed 65 dB(A) during the day (NADF-005-AMBT-2013 standard).

 Heart rate

This value corresponds to the number of heartbeats per minute.


The inhalation value corresponds to the dose of the NO2 pollutant inhaled during the trip in taking ventilation into account (number of litres of air inhaled per minute).

 Metabolic Equivalent of Task (MET)

This measure allows one to evaluate the intensity of a physical activity. It ranges from 0.9 (sleep) to more than 18 (running at 17.5 km/h or more). There are several MET scales that distinguish between several levels of physical activity, especially:

  • low-intensity physical activity (MET under 3);
  • moderate-intensity physical activity (MET from 3 to 6);
  • high-intensity physical activity (MET above 6).

 Air pollution (NO2)

Air pollution was measured using a portable Aeroqual 500 device with nitrogen dioxide (NO2), temperature, and humidity sensors. The NO2 pollutant was chosen as its emissions mainly come from the engines of motor vehicles. According to the World Health Organization (WHO), the air quality guideline value that should not be exceeded is 200 μg/m3, over short durations (one hour). Beyond this threshold, “it ⦋NO2⦌ is a toxic gas which causes significant inflammation of the airways” (WHO).