This exchange region is complex and crucial for understanding the stratospheric chemistry and the evolution of the ozone layer. We have a long experience in studying the aerosol variability and the trace gas chemistry in this region. We are also interested in the impact of small (gravity wave, turbulence) and large scale (Brewer-Dobson circulation, FRIAC, polar vortex) dynamics on the distribution of aerosols and chemical tracers. Regularly, plumes of fires or volcanoes can impact this region. The unpredictability of these phenomena has led us to develop lightweight instruments that can be deployed quickly and from any site. We also participate in the study of greenhouse gases (CH4, CO2, N2O) emitted from natural areas (wetland and agricultural). To achieve this issue, we have developed several generations of infrared spectrometers and developed our expertise in modelling. We are also involved in the study of soil and air pollution through the development of original protocols for pollution control and the study of reaction mechanisms. For more than 30 years we have also contributed to the success of many space missions such as the Huygens and Rosetta missions, which have respectively studied the titanic environment and the 67P/Churyumov-Gerasimenko comet. Currently we are involved in the JUICE mission which will allow us to study the environment of the Europe satellite. For 25 years we have also been participating in the PROGRA2 program to study the optical properties of grains through the analysis of samples in microgravity on board the Airbus Zero-G.