The Ballon de Paris is a popular attraction for those wanting to get high above the chaos and clutter of Paris streets. The views are spectacular.
However, the giant helium balloon which is tethered to the ground and ascends 300 metres into the Paris sky, does more than just offer joy rides. It doubles up as an atmospheric observatory.
Its gondola is equipped with three sensors for measuring particulate matter emitted by automobiles and industries, ozone concentration and nitrogen oxides.
"With the LOAC (Light Optical Aeorosol Counter) we collect the particles. They pass through a laser beam and we measure the light they scatter. We can retrieve information of the size distribution of the particles between 200 nanometers up to 30 micrometers.
With this, we can derive the concentration of particles per cubic meter," Jean Baptiste Renard of the French national scientific research agency or CNRS told RFI.
Renard listed the advantages of having a laboratory attached to a balloon. "It allows us to perform the measurements from the ground to up to 300 meters.
"This is unique because we can see the vertical transport of the particles. We can follow the pollution in real time and also during the ascent of the particles above Paris," he said.
Renard and his team have been taking continuous measurements for the past seven years.
The balloon with 6000 cubic meters of helium is installed at the Parc Andre Citroen and has been operational since 1999.