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A Two-city Study of Air Quality in Vietnam 2018-19: Source Apportionment Using PMF Applied to Offline AMS Data
ZAINAB BIBI, James Allan, Thomas Bannan, Alex Baker, David Oram, Duong Huu Huy, To Thi Hien, Hugh Coe, Saleh Alzahrani, University of Manchester, UK
Abstract Number: 358
Working Group: Aerosol Chemistry
Abstract
Hanoi and Ho Chi Minh City (HCMC) in Vietnam are very heavily polluted cities, with annual average PM2.5 concentrations of 50.5 and 42 µg m–3 respectively (Hein et al., 2019). As part of a collaborative project between the UK and Vietnam, “A Two City study of Air Quality in Vietnam”, PM2.5 was collected on glass fibre filters in 2018 and 2019 from different sites in Hanoi and HCMC. Filter extracts were then analysed using a High-Resolution Aerosol Mass Spectrometer (HR-AMS) to study organic and inorganic compounds. Positive Matrix Factorisation (Paatero and Tapper, 1994) was performed to discriminate between different sources of pollution, with the objective of informing policymaking decisions. The results of this study showed the highest concentrations of organics followed by nitrates, sulphates, ammonium and chloride while PMF analysis identified the data into four different sources in Hanoi and HCMC both. The first factor contains a marker associated with Mannitol, which can be associated with the ejection of the fungal spores. The second factor is highly oxidised organic fragments with the high peaks at m/z 28 and m/z 44 and representing the substantial fraction of organic matter from both sources i.e. natural biogenic emissions (Xu et al., 2015a; Chen et al., 2015) and anthropogenic sources mainly vehicle emissions (Presto et al., 2014). The third factor is semi-volatile oxygenated OA (SVOOA), which is a mixed factor mainly coming from the secondary sources. The fourth factor has peaks associated with levoglucosan which is a marker associated with biomass/wood burning. This study will provide an important additional information about sources of organic aerosols in both cities and will be helpful for policymaking in the future.