Outdoor air pollution is estimated to have caused 4.2 million premature deaths worldwide in 2019, with the vast majority of these premature deaths occurring in low- and middle-income countries (World Health Organisation, 2022). The greatest number of deaths occur in South-East Asia and Western Pacific Regions, including India and China.
Although many harmful air pollutants are emitted directly into the air (primary pollutants), they can then undergo complicated chemical processing to produce secondary air pollutants, such as ozone. Although stratospheric ozone plays an important role in shielding us from harmful radiation, it is harmful both crop and human health at ground-level. Ground-level ozone is formed in a non-linear photochemical cycle, from the precursor species NOx (NO + NO2) and volatile organic compounds (VOCs).
My research uses chemical box models, incorporating observational datasets from field campaigns, to understand the chemical drivers of ground-level ozone formation in highly polluted urban regions, including Manchester, Beijing and Delhi. A comprehensive suite of VOCs is measured at the location of interest using both one and two dimensional gas chromatography (GC-FID and GC x GC-FID). A wide range of VOCs can be measured using this technique, from less reactive small hydrocarbons such as ethane, to larger and more reactive species including aromatics and monoterpenes. These measurements allow for the development of a detailed chemical box model, incorporating the Master Chemical Mechanism, which can then be used to understand the current drivers of secondary pollutant production in each location, and can also be used to assess changes in the future drivers of ozone under different air quality and climate change outcomes.