The air pollution problems affecting Beijing and north-eastern China are well documented, but the formulation of cost-effective solutions requires further research. In a study funded by the UK Natural Environment Research Council and Medical Research Council and the Chinese Natural Science Funding Council, researchers from the UK and China have collaborated in studies with the following aims:

• to determine the emission fluxes of key pollutants and to measure the contributions of different sources, economic sectors and regional transport to air pollution in Beijing;
• to assess the processes by which pollutants are transformed or removed through transport, chemical reactions and photolysis and the rates of formation and conversion of particulate matter via atmospheric reactions;
• quantify how the detailed properties of particulate matter evolve and can influence its physical properties and behaviour in the atmosphere and elucidate the mechanisms whereby these properties may interact and feed back on urban-scale and regional meteorology;
• to develop numerical models capable of reliably simulating air quality within Beijing and its local region and prediction of the impacts of mitigation measures;
• to determine exposure of Beijing inhabitants to key health-related pollutants using personal air pollution monitors and assess the associated links between air pollution exposure and health impacts;
• to determine the contribution of specific activities, environments and pollution sources to the personal exposure of the Beijing population to air pollutants derived from outdoor sources.

Implementation of the research was through two major field campaigns based in Beijing and rural sites outside of the city which took place in November–December 2016 and May–June 2017. The work involved measurements of air pollutants as well as key precursors, reactive species and meteorological variables in three spatial dimensions, with a view to creating an enhanced understanding of the processes determining pollutant concentrations, especially in relation to particulate matter and photo-oxidants.

This special issue brings together the research involving studies of the atmospheric physics and chemistry of pollutant sources and processes affecting the Beijing atmosphere. Although linked to studies of personal exposure and human health, the majority of the latter work will be published elsewhere.

Please note that it is intended that this special issue only feature articles associated with the APHH-Beijing programme. When submitting an article, please indicate in the author’s statement which project it is associated with. If in doubt, please contact one of the special issue editors first.