Les Halles: Construction


The construction site at Les Halles is part of a larger redevelopment project, which also includes a new public garden, a larger pedestrian district and greater number of easier-to-use pathways and routes, a larger and more functional regional train station and reorganized underground road network, and an enlarged, refurbished shopping centre and more cultural facilities. However, it is the construction of La Canopée (the Canopy), a new metal and glass building inspired by the natural canopy of forests, that is most striking.


One could argue that work on the Canopy has brought many benefits to the surrounding community. SemPariSeine is the organization charged with managing the “réaménagement” of the area, and it includes representatives from government and civil society. They claim that construction work, which is strictly limited to certain hours of the day to minimize noise, has also led to greater responsiveness to the concerns of the site’s neighbors. For instance, if a store owner reports a leak in the soundproof barrier, it is fixed immediately. Completion of the construction is expected mid-2015. In the meantime, the site bustles with workers and machines, as you can see here:


Walking on Rue Berger, where the outdoor construction can be seen through wire fence at some points, a member of our team felt her eyes water and her nose itch, despite having no allergies. When we ascended to the observation platform, it became clear that dust might have been the culprit. A hard-hatted man was driving a cart, shoveling loads of dirt. This spread the dust that wafted across an expanse of cement, carried by the wind to passersby and observers on the platform.
There is immense traffic at Les Halles. 300,000 people pass by it everyday, including families with small children, workers, and virtually all tourists that arrive in Paris. Thus, the environmental concern of dust and air pollution is urgent and significant.

Method and Results


We programmed an Arduino, fitted with a dust sensor, at the Open Lab in order to compare dust density in different sites of Les Halles, a measure of the effect of construction on the pedestrians and people living in the area. Our methodology revolved around obtaining our data and comparing it with existing studies and published measurements regarding the environmental impact of the site. However, we realized that a single Arduino was not the best for the job, because the sensor was too small, and there was too much noise from variables we could not control in the system, such as humidity and temperature. We compared measurements at the Les Halles construction site, the adjacent Nelson Mandela garden, and the courtyard at the CRI as a control, expecting there to be more dust closer to the construction.

However, measurements of dust density were consistently 0.12 mg/m^3, regardless of location. We ran the same test in different sites and did not observe a deviation of more than 0.01. An example of this are the following measurements, which quantify (i) the voltage in the circuit at the time of our measurements and (ii) the dust density in mg/m^3:






We believe that using a more sophisticated Arduino or a better calibration offset on our circuit could have given us greater results. The current equation (a calibration offset for the sensor that we used) comes from a user project and may not be sufficiently accurate.

Proposed improvement

Monitoring of air pollution is critical to identify hazardous sites, of special significance in particularly dense areas of the city. Existing initiatives to provide public information include Airparif (Association de surveillance de la qualité de l’air), which provides pollution data for  specific sites and timeframes, and the World Air Quality Index (AQICN), which provides real-time measurements of air pollutants (O3, NO2, SO2, CO, and more), temperature, humidity, and other factors, displayed in maps. However, Airparif’s spreadsheets for Les Halles, once downloaded, were empty for this month, and AQICN does not provide data specific to Les Halles, but rather the entire region of Paris Centre.
Thus, we propose that environmental measurements specific to the Les Halles construction site be conducted, and that resulting data be published online. Such monitoring and surveillance could include air pollution (dust, O3, CO, and other harmful agents), temperature (particularly relevant in the city, where summer heat waves are a threat), and even noise. This will ensure that the construction site is safe and unobtrusive to its neighbors and visitors. It will also provide data that will inform the public of where environmental hazards need to be addressed.

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