David Cohen has been a pioneer and world leader in the industrial and scientific development and application of accelerator-based ion beam techniques in many different disciplines including pollution studies, environmental science, materials analysis, biology and archaeometry. These techniques include Proton Induced X-ray Emission (PIXE), Rutherford Backscattering, Nuclear Reaction Analysis, ion and X-ray microbeams and Heavy Ion Recoil Time-Of-Flight Spectroscopy. He is recognised internationally as the world's leading authority on fine particulate matter in air pollution which is of key importance to human health as fatalities caused by these particles are comparable in number with those from motor vehicle accidents.