Breathing is obviously an essential activity; but depending on your location (a busy road or industrial location) every breath you take has the potential to introduce dangerous gases and airborne particles to your lungs.

Prof Kelly's research focuses on how the lung defends itself from these challenges and why, for some of us, these defences sometimes fail. Much of his current work examines the oxidant mechanisms underlying air pollution-induced lung injury.

Prof Kelly is trying to understand how pollutants such as ozone, nitrogen dioxide and tiny traffic-related particles interact with the lung and initiate injury.

As well as conducting studies in healthy volunteers he is particularly interested in how these events differ between healthy subjects and those with pre-existing airways disease such as asthma. The primary focus of these studies relates to the events occurring within the respiratory tract lining fluid (RTLF) compartment of the lung. This thin layer of fluid, which lines the surface of the lung, represents the first and maybe most important line of defence against inspired pollutants. Prof Kelly suspects that oxidant/antioxidant events occurring in the RTLF are pivotal to understanding the impact of air pollution on the lung. Since many respiratory diseases involve inflammation, RTLF antioxidants have also the potential to defend the lung against free radicals released by invading white blood cells.

In collaboration with clinical colleagues at the University of Umea in Sweden, Prof Kelly utilises bronchoscopy and bronchoalveolar lavage procedures to investigate the nature of oxidant/antioxidant interactions occurring in the RTLF compartment. These studies, in combination with cell culture and in vitro approaches, have allowed Prof Kelly and colleagues to develop an understanding of the time-course of events in the airways following oxidative challenge.

These findings have led them to realise the need to obtain a better understanding of how diet and genotype interact to determine an individual's complement of RTLF antioxidants. Prof Kelly and colleagues have obtained data on the antioxidant defence network within RTLF of healthy individuals and are investigating how diet and genetic background can influence this.

In addition to these chamber-based volunteer studies, Prof Kelly and colleagues are taking advantage of the natural experiments that are taking place in London following the introduction of traffic management schemes such as the Congestion Charging Scheme (CCS) and the Low Emission Zone (LEZ). Both schemes have the potential to influence vehicle emissions and thus air quality in London. With colleagues in Imperial College, St George's and the London School of Hygiene & Tropical Medicine Prof Kelly is determining if this is the case and if they can demonstrate a health benefit of these traffic intervention schemes.