Jonathan’s current research focuses on the effects of air pollution on airway infection and the fate of inhaled carbonaceous particulate matter in vivo. He has also performed randomised controlled trials of treatments for asthma. He has been a member of the UK Department of Health’s Committee on the Medical Effects of Air Pollution and Chair of the European Respiratory Society’s Tobacco Control Committee. He contributed to reports from the Royal College of Physicians and Royal College of Paediatrics and Child Health (UK) on the health effects of indoor and outdoor air pollution.