What air quality in car parks?


Courtesy of ETHERA

The quality of the air in the car parks is very variable. The main pollutants are often found above the recommended limit values, exposing the users but especially the operating personnel to health problems. This air quality varies according to three main parameters:

  • The type of parking (overhead or underground)
  • Traffic attendance and parking
  • The type of ventilation (servo control and control parameter) or air treatment (purification)

What air quality in car parks?

Pollutants present in car parks
The main pollutants are fine particles (PM), CO, NO2, SO2, NO, O3, benzene, formaldehyde. Particles are mainly from brake pads, tire wear and diesel combustion. But also, NO2, NO, SO2, formaldehyde due to the combustion of hydrocarbons and benzene evaporation tanks. Noted that the concentration of benzene can reach significant levels, especially in operating rooms exposing staff. Some studies show maximum concentrations of benzene at 60 μg / m3 during the summer and 150 μg / m3 at the NO2 for guide values (which are not the ELVs) of 2 μg / m3 and 20 μg / m3, respectively.

Regulation on air quality in car parks
There are no regulatory values for air quality in underground car parks to date.

The CO content must not exceed the following values:

  • 50 ppm (60 mg / m3) over any 30 minute period;
  • 90 ppm (100 mg / m3) over any 15 minute period;
  • 150 ppm (170 mg / m3) in instantaneous value

The NO2 content must not exceed 0.4 ppm (0.8 mg / m3 or 800 μg / m3 ) over any 15 minute period.

AFSSET recommendation on air quality in the car parks covered here .

Ventilation in the car parks
The extraction of the air allows its renewal. It is also possible to meet ionization air purification systems to cut down fine particles. Ventilation systems are often enslaved to the parking lot. This method is inefficient for residual benzene emitted by parked vehicles. Another method consists in slaving the ventilation to the CO concentrations for which it is possible to find target values, unfortunately there is no strong correlation between the CO concentration and the other pollutants. Ideal and control the ventilation or purification systems on the concentrations of CO, CO2, TVOC, NO2 (or NO) and PM.It is possible to find micro-sensors for these parameters, allowing inexpensive air quality monitoring station installations.

How to measure the air quality in car parks?
It is possible to install multi -parameter air quality analysis stations incorporating formaldehyde, CO, VOCs, NO2, NO and PM. These stations can be connected to the ventilation or air purification control system. It is also possible to enslave these systems according to the external pollution.

Which means of communication to use for the air analysis stations?
Underground parking limits their means of communication because of the massive infrastructure. It is advisable to use long-range means (LPWAN) such as Sigfox, LoRa, LTE-M or NB-IOT. Short communications carried WIFI type, Bluetooth, Zigbee are to be avoided. It is also possible to use private IoT long-range networks by level.

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