Chemical and toxicological properties of aerosol emissions subject to atmospheric processing

We need to account for atmospheric aerosol emissions not just in terms of directly emitted particulate matter but also gases that may form secondary particulate matter through atmospheric processing. However, we currently lack sufficient fundamental scientific understanding governing the chemical formation and toxicological impacts of these aerosols. This project seeks to develop this from the EPSRC physical sciences research area, but with an interdisciplinary thematic broadening sabbatical (TBS) crossing into toxicology.

Oxidation flow reactors (OFR) can provide a standardised method of simulating atmospheric processes on sources of emission, and thus a method of quantifying the aerosol-forming potential of these emissions. This can help inform emission inventories and account for transboundary pollution contributions. This PhD will develop and apply a new protocol for the generation of these aerosols using the newly commercialised Dekati OFR and quantitatively investigate the processes governing long-range PM formation and human health impacts

This work will build on previous experience gained during the NERC HIP-Tox consortium grant, where a number of standardised and repeatable sources (e.g. wood stove, cooking, diesel engine) have been used to generate emissions, injecting them into a large photochemical reaction chamber. This complex methodology is unsuitable for routine emission evaluation, and the infrastructural requirements too burdensome to systematically explore the range of secondary pollutants across emission sources and atmospheric conditions. This PhD will aim to create similar atmospheric processing simulations using the Dekati OFR. The operating conditions of the OFR will be optimised to simulate various chemical regimes and the effect of this on the mass and the composition of the aerosol will be quantified using state of the art aerosol instrumentation at Manchester, including aerosol mass spectrometers. This unique combination of previous work to provide the chemical and toxicological basis for the experiments for these real-world sources will provide new important insights to the fundamental processes.

The project aims to develop a protocol for the generation and quantification of secondary and aged primary aerosols using an oxidation flow reactor (OFR), applicable to a range of important real-world sources, and to subject these to chemical and toxicological analysis. These results can be used to inform models of atmospheric chemical transport models and public health impacts of air pollution. This will focus on the following specific objectives:

1. Characterise the physical and chemical transformations induced by the OFR on the following aerosol sources, using a variety of on- and offline chemical analytical techniques
a. Euro 6 diesel engine
b. Wood burning stove (using a variety of fuels)
c. Domestic food preparation
and further opportunistic exploration of a range of other secondary sources
2. Optimise the conditions with the OFR to be most representative of regional atmospheric ageing, to provide new insight into long range impacts of pollution sources on air quality, with a focus on possible changes to atmospheric conditions in a changing climate.
3. Further develop a method of sampling the aerosol into a physiologically relevant media, based on a detailed compositional analysis of lung lining fluids, suitable for toxicological assessment, without capturing excessive amounts of gaseous oxidants, for the purposes of evaluating the impacts of chemical processing and secondary aerosol formation on health.