Atmospheric aerosols have major impacts on climate, air quality, and health, yet their chemical composition remains an analytical challenge due to their small size and low mass. We present an approach for aerosol chemical analysis combining nanoelectromechanical systems and Fourier transform infrared spectroscopy (NEMS-FTIR), offering simultaneous quantification of organic functional groups, ammonium sulfate, and equivalent black carbon with orders-of-magnitude lower detection limits over existing methods. The miniature, lightweight design allows for deployment on airborne platforms. Field demonstrations show that capturing distinct chemical compositions at the surface and aloft is possible, and they highlight the capacity of NEMS-FTIR for high-sensitivity, high–time-resolution aerosol analysis, revealing short-term variations in chemical composition previously inaccessible to conventional methods. NEMS-FTIR is therefore expected to advance the study of climate-relevant particles across different environments, from polluted urban to pristine polar. Beyond atmospheric science, this technique offers broader potential in nanoparticle analysis where mass constraints or time resolution is critical.