During our careers, we met Jean-François Muller essentially in the context of scientific meetings and PhD examination panels, in relation with the use of Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. However, one of us (PCM) had also the opportunity to meet him in a less well-known aspect of his implication in societal activities related to the monitoring of air quality. In this recollection of Jean-François Muller, we would like to recall how his science has also served societal causes.