Research interests

• Tropospheric chemistry of volatile and semi-volatile organic compounds
• Chemical mechanism development and application
• The Master Chemical Mechanism (MCM) 
• Air pollution modelling and interpretation of ambient monitoring data  
• Kinetic and mechanistic studies of elementary atmospheric oxidation processes
   

The emission of trace materials into the atmosphere can have a variety of influences on the environment, ranging from immediate health impacts in the locality of the release to world-wide effects on atmospheric composition and climate. Organic compounds, such as hydrocarbons, are emitted in large quantities from both natural and man-influenced sources, and contribute to many of the well-publicised environmental phenomena, for example, photochemical smog and global warming. It is estimated that about 2 billion tonnes of organic material are emitted into the atmosphere each year. Natural sources include emissions from vegetation (e.g., forests), and such sources dominate when total global emissions are considered. Man-influenced emissions result from many sources, in particular road transport, distribution of petrol and other fuels, solvent usage and some industrial processes. In populated regions, such as the UK, emissions from such sources represent the major input of organic material into the atmosphere.

Some emitted organic compounds (e.g. benzene, 1,3-butadiene and "polycyclic aromatic hydrocarbons, PAH") are known to be detrimental to human health, for example as carcinogens. However, a much wider impact results from the chemical processing of organic material in the atmosphere, which leads to the generation of a variety of products, sometimes known as "secondary pollutants". Of particular importance is the generation of "ozone", which is produced from the sunlight-initiated oxidation of volatile organic compounds (VOC) and nitrogen oxides (NOx). Ozone is a major component of photochemical smog, and is known to have adverse effects on human health, vegetation (e.g. crops) and materials. It is also a "greenhouse gas" which contributes to global warming and climate change. Another by-product of these oxidation processes is the generation of involatile organic oxidation products which can contribute to the mass of airborne particles. Particulate matter in the atmosphere has an important influence on visibility and climate, through the scattering of light and UV radiation, and also has direct health implications because fine particles can be inhaled into the lung.