Quantification of Airborne Pollutant Sources and Effects

Professor Mathew Heal’s research provides the scientific evidence base to improve air quality measurement standards and drive policy action on air pollution.

The challenge: Improving air quality for human health and the environment

Air pollution not only has devastating consequences for human health – killing an estimated seven million people worldwide every year – but is closely linked to climate change and the health of ecosystems globally. Air pollutants are emitted directly into the atmosphere from multiple sources but are also formed, altered and removed by chemical reactions – making chemistry key to understanding and managing their impacts.

Journal cover showing the air pollutant article

Measurement and modelling of atmospheric chemistry

The Heal research group, working with colleagues across environmental and health disciplines, uses a combination of field measurements and modelling to investigate atmospheric composition, surface-atmosphere fluxes, and air pollution, and the impacts of these on the terrestrial environment and on human health. Their work covers the three most important contributors to poor air quality – particulate matter (PM2.5), ozone (O3) and nitrogen dioxide (NO2).

Impact on air quality monitoring and policy

The resulting research has provided the scientific evidence base to improve air quality measurement standards and drive policy action.

Improved monitoring of NO2: Since 2008, protocols for measurement of ambient NO2 by passive diffusion tube have incorporated new standards based on Heal group research. As a result, measurements of this key pollutant are more accurate and reliable across all urban areas of the UK, affecting more than 139,000 measurements made annually, at a cost of £500,000.

Policy input: As a member of two government advisory groups – DEFRA’s Air Quality Expert Group (AQEG) and the Department of Health’s Committee on the Medical Effects of Air Pollutants (COMEAP) – Heal advises governments on air pollution and its consequences for health. Recent work for these groups has focused on setting targets to reduce PM2.5 in the Environment Bill, possible links between air pollution exposure and severity of Covid-19 outcomes, and the response of air quality to lockdown.

Policy action on domestic wood burning:  By measuring carbon-14 abundance in airborne PM2.5 for the first time in the UK, Heal group research showed that a large part of the carbon is contemporary not fossil – the result of emissions from small-scale domestic word burning – a finding further supported through modelling. These emissions are now included in policy action through the 2019 Clean Air Strategy.

Quantification of the health effects of ozone: Heal group research with measurements and models of O3 has helped quantify the link between exposure to daily levels of O3 in the UK and premature mortality – and shown the increased severity of this effect on the hottest days. By considering future scenarios, this work forms part of the evidence to increase preparedness for and mitigation of health effects from air pollution and climate change.

Related publications

  1. Heal, M.R., Naysmith, P., Cook, G.T., Xu, S., Raventos Duran, T., Harrison, R.M., 2011. Application of 14C analyses to source apportionment of carbonaceous PM2.5 in the UK. Atmospheric Environment 45, 2341-2348.
  2. Heal, M.R., Heaviside, C., Doherty, R.M., Vieno, M., Stevenson, D.S., Vardoulakis, S., 2013. Health burdens of surface ozone in the UK for a range of future scenarios. Environment International 61, 36-42.
  3. Ots, R., Heal, M.R., Young, D.E., Williams, L.R., Allan, J.D., Nemitz, E., Di Marco, C., Detournay, A., Xu, L., Ng, N.L., Coe, H., Herndon, S.C., MacKenzie, I.A., Green, D.C., Kuenen, J.J.P., Reis, S., Vieno, M., 2018. Modelling carbonaceous aerosol from residential solid fuel burning with different assumptions for emissions. Atmospheric Chemistry and Physics 18, 4497-4518.
  4. Defra, 2008. Diffusion tubes for ambient NO2 monitoring: practical guidance for laboratories and users. A report by the Defra Working Group on Harmonisation of Diffusion Tube Methods. AEA Energy & Environment, Didcot, UK. Report no. AEAT/ENV/R/2504.

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