Why does the balloon change color?

In partnership with AIRPARIF®, the balloon indicates the quality of the air in Paris, through the ATMO index, which entered into force on January 1, 2021:

• This is a qualitative daily index of air quality.
• More representative of air quality in France, it takes into account a pollutant that was not counted until then: PM 2.5.

The ATMO index illustrates in a simple and easily understandable way the quantity of the five most problematic pollutants for air quality (nitrogen dioxide, sulfur dioxide, ozone and three types of particles), from from the following color palette:

Two series of pictograms appear on the envelope: flashing vehicles on the one hand, and the main monuments of Paris on the other.

Thus, when the silhouette of the Eiffel Tower changes from turquoise to yellow, this will indicate that the quality of the ambient air has gone from good to degraded.

Thanks to its luminous intensity, supplied with “clean” energy thanks to a photovoltaic textile attached to the envelope of the balloon, this one is visible to 400,000 Parisians every day.