Prof. Noel Aquilina from the Department of Chemistry at the University of Malta, as an active member of the COST Action , is a co-author of an important review paper in the influential journal Science of the Total Environment entitled .
A working group was tasked with reviewing through the last 13 years of scientific literature to address the question: what do existing measurement and model results reveal about indoor air chemistry?
Source apportionment is a modelling exercise which requires a substantial amount of chemical information obtained from the collection of air samples from any area representing air pollution problems and analysing them for specific chemical signatures. Over the years several modelling suites have been developed for different sources however most of them focussed on the outdoor environment. Indoor air quality is a different problem, where indoor chemistry is very complex and challenging and the knowledge about the outdoor environment does not necessarily apply to the indoor environment.
To further compound the problem most chemical transformations in the indoor environment occur at different rates, making the application of existing methodology possibly unsuitable.
Almost all the studies reviewed used the size distribution or the chemical composition of particulate matter or dust as tracers to apportion the measured concentrations to their potential sources. The most commonly used receptor models were Positive Matrix Factorisation, Principal Component Analysis and Chemical Mass Balance.
The chemical information in the indoor environment which is somewhat easy to measure to date, allows scientists to identify sources under the following categories: i) building materials and furniture, ii) indoor combustion, iii) cooking, iv) resuspension, v) cleaning and consumer products, vi) secondary pollutant formation, and vii) other products and activities. Outdoor sources such as traffic, long-range transport, combustion and natural sources contribute to a different extent to the indoor pollutant levels, mainly due to local/regional topography and climate and also depending on the modelling approach chosen.
In this publication it was highlighted that more comprehensive research on the characterisation of sources is necessary. One of the major challenges is defining detailed chemical profiles of sources with highly varying spatial and temporal characteristics. A number of research gaps regarding the methodology of source identification in indoor air were highlighted.
The most important ones included the optimisation of indoor air monitoring, the data necessary and the inclusion of indoor air physical and chemical processes in the already quite developed source apportionment modelling methodology. The findings of this paper will be presented in the in Nov-Dec Belgrade 2023.
Prof. Aquilina has been invited to co-guest edit two new Special Issues. The first one is entitled of the MDPI journal , under the new section . This special issue is a natural consequence of the abovementioned publication because so many aspects of the indoor environment are still unknown and need more scientific input.
The second one is entitled “Dedication to Roy Harrison” which will be available in the CSIRO Publishing journal , is intended to celebrate the illustrious career of , the Queen Elizabeth II Birmingham Centenary Professor of Environmental Health at the University of Birmingham.
Prof. Harrison pioneered research in air pollution, studying emissions from various sources, atmospheric chemical and physical transformations and how exposure to several pollutants effects human health. Most of the research informed and influenced the development of policy to improve air quality both in the UK and globally. Prof. Aquilina continued to collaborate with Prof. Harrison for the last fifteen years, with the main focus being the measurement and modelling of exposure to a suite of combustion driven carcinogenic pollutants in different environments.
