A Mixed Strategy for Characterising Gaseous Air Pollutants and Aerosols at an Urban Air Quality Site in Europe

Abstract

Manchester Air Quality Supersite (MAQS), located at Firs Botanical Garden in Fallowfield, Manchester, is monitoring the urban air quality by routine measurements of gaseous air pollutants, aerosols, and meteorological variables and simultaneous reports. Since data collection at this air monitoring site began in September 2019, an in-depth and comprehensive characterisation of air pollution is missing. At the same time, due to the COVID-19 pandemic, air pollution levels in the UK have been strongly affected by the restrictions on human activities, which significantly reduced the emissions of air pollutants since March 2020. In addition, aerosol pollution poses serious harm to human health, especially ultrafine particles that can penetrate deeper into the human body due to their small size. Therefore, gaseous pollutants and aerosols at the MAQS supersite have been characterised in this thesis to determine their sources, formation processes, and levels. A mixed strategy has been developed in this thesis in a combination of spatial and temporal change assessment, machine learning modelling, and specific pollution source analysis, here are the key findings of the thesis: (1) The operation of the MAQS supersite has been proven to be a representative of the air pollution in Manchester, whereas the lockdown that began in March affected the representation of year 2020. (2) The characterisation of the impact of the lockdown of COVID-19 proved the significant change of air pollutant levels by a mixed machine learning process including the emission-driven and meteorology-driven scenarios, proving that it has no long-term impact on air pollution levels in urban Manchester and the air quality has “recovered” since mid-2022. (3) The assessment of aerosol pollution at the MAQS by the clustering analysis of the particle size distributions confirmed the significant impact of the traffic emission on ultrafine particles (UFPs) and Aitken mode particles dominated the UFPs, while regional air masses contributed more to larger-sized particles in urban Manchester. (4) Manchester Airport has a significant influence on the UFPs in the surrounding areas, however UFPs in Manchester city areas have not experienced any significant direct impact.

Date of Award	6 Jan 2025
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Hugh Coe (Supervisor)