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In occupational and public health there is a need for measurement and speciation of chemicals in ambient air to achieve control of air pollution and minimize health risks. In this work two methods of analysis are developed for the analysis of polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) under ambient air conditions. Both methods involve the use of thermal desorption techniques with gas chromatography-mass spectrometry (GC-MS). For the measurement of polycyclic aromatic hydrocarbons (PAHs) airborne particulate samples are obtained by collection on small glass fibre filters. The volatile materials from these are thermally desorbed in two stages and transferred to a Gas Chromatograph-Mass Spectrometer analytical system. Results from studies of particulate samples obtained from sites in the region of Uxbridge, Middlesex are reported for eight selected polycyclic aromatic hydrocarbons (PAHs). Measurements on samples obtained directly from vehicle emission sources with the engine used under different running conditions are also reported. In the method of analysis of volatile organic compounds in air, samples are absorbed into 4mm Carbotrap 300 tubes and thermally desorbed and passed into a gas chromatography-mass spectrometry (GC/MS) or gas chromatography (GC) using helium as carrier gas. The Carbotrap absorbers used, show complete absorb/desorb reversibility, are thermally stable and do not react chemically with injected hydrocarbon standards. To demonstrate the value of the method analytical results obtained under ambient air conditions on the Brunel University campus (Uxbridge, Middlesex) are reported. Six selected low molecular weight aromatic hydrocarbons namely benzene, toluene, ethyl benzene and m-, p- and o-xylene are investigated in detail. The concentrations of these compounds were measured and results related to traffic flow rates and meteorological conditions to establish the fact that vehicle exhaust emissions are the main sources of the volatile organic compounds (VOCs) pollution at the collection sites. A study of volatile organic compounds (VOCs) levels in ambient air in Tehran (Iran) in which 55 hydrocarbons are identified is reported. A detailed study is made of the concentrations of the six hydrocarbons benzene, toluene, ethyl benzene and m-, p- and o-xylene because high concentrations of these pollutants can produce potential health problems. It is shown that the nature of the geographical location and the day time temperature play an important part in determining the composition of the mixture of pollutants in Tehran. Samples obtained directly from internal combustion engines with and without catalytic converters are also analysed using the method developed and the results show that there is a large depletion in aromatic hydrocarbons when toluene is reduced to a greater extent than benzene. The analytical method is also used to compare vehicle emissions from engines under cold start and hot start conditions.

Sol-gel production of catalyst supports has been investigated in order to produce homogeneous, high surface area alumina/zirconia materials. A novel microwave method of preparing colloidal Pd has been developed and a range of alumina/zirconia supported Pd catalysts has been produced. These have been tested for activity in terms of temperature programmed three way catalysis (simultaneous removal of NO, CO and C3H8 from a simulated car exhaust stream) and from the array of catalysts produced a suitable catalyst was chosen for further investigation. This catalyst had a 3% zirconia / 97% alumina support and contained ~1% Pd by weight and was examined for activity in the NO + CO + O2 system at temperatures below 500°C. Temperature programmed catalytic experiments revealed the reactions to be chemically controlled below ~400°C but diffusion controlled above this. CO temperature programmed reduction was used to examine the oxidation state of the Pd and revealed a complex Pd/PdO system to be present involving bulk PdO and surface oxide. Further kinetic studies showed that the reactions between NO, CO and O2 to have positive orders in all components. The reaction rates were stable over a wide range of conditions and the NO + CO reaction proved to have a low selectivity towards N2O. In-situ DBIFTS experiments alongside transient pulse work were used to illustrate low CO adsorption which indicated that these reactions proceeded via a redox mechanism in which Pd is oxidised by NO or O2 before being reduced by CO. The support material was examined by XRD following extended heating regimes and then compared to an identically treated sol-gel alumina. The zirconia doped alumina was found to possess a far greater thermal resistance to sintering than the pure alumina material and this was attributed to Zr4+ ions preventing the diffusion of Al3+ to form a-alumina.

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Aircraft engine emissions from civil aviation cause several adverse effects to the atmospheric environment. These emissions are among the known major contributors to changes in atmospheric chemistry and global climate change. One way in which the international community has responded to the problem has been the adoption of several international treaties, generally dealing with subjects such as protection of the ozone layer, long-range transboundary air pollution, and global climate change. / The other way in which the problem has been dealt with is the adoption of an industry-specific international regulatory regime for controlling aircraft engine emissions from civil aviation. In this regard, the international community has, through the law making functions of the International Civil Aviation Organization (ICAO), adopted the mechanism of Standards and Recommended Practices (SARPs) to establish a regulatory framework aimed at reducing environmentally harmful engine emissions. These SARPs, though international in nature, are to be implemented at the national level by the member states of ICAO. / This thesis provides a review of current understanding of the effects of aircraft engine emissions on the atmospheric environment and an analysis of the international responses to the problem. In particular, it focuses on the industry-specific regime adopted by ICAO and considers whether it is an effective tool for achieving a balance between the safe and orderly development of civil aviation and the human environment.

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