Air pollution in Oxford is one of the city’s most pressing issues. Our present understanding of Oxford’s air quality in the past has come from scant archival evidence, from which significant periods of time are poorly understood. To better understand its history, and predict its future impact, outdoor archives which have been exposed to polluted air may be investigated. One of these potential archives is stone sculpture.

Three generations of Sheldonian stone heads

Three generations of stone heads: (left to right) 1st generation head (1669) in Worcester College, Oxford (credit: Fusade); 2nd generation head (1869) in a private garden in Summertown, Oxford (credit: Fusade/Orr); 3rd generation head at the Sheldonian Theatre, Oxford (credit: Wilhelm).

Three generations of Sheldonian Heads have stood prominently in the heart of Oxford since 1669, exposed to the same air as Oxford’s population. The first two generations of Heads are still around in Oxford Colleges, private and public gardens. To us, the Heads are a unique 350-year record of urban architectural responses to climatic and environmental change.

Preliminary investigations at the Oxford Resilient Buildings and Landscapes Lab (OxRBL) have shown that various pollutants, including the toxic metal lead (Pb), are present in the surface crusts of the Sheldonian Head sculptures. The source of the pollutants is unclear, so definite conclusions regarding the type of pollution cannot be drawn. However, by interrogating the isotopic composition of the Pb, it should be possible to determine whether the source is natural or man-made.

This project is an opportunity to shed light on the history of Oxford’s air pollution using heritage sculpture as a proxy for past exposure. Additionally, by analysing modern crusts, we should be able to contextualise current levels of air pollution in Oxford and enable a better understanding of sources of pollution. Our sampling strategy is non-invasive and aims at 3 samples (~British stamp size) per Sheldonian Head in hidden places such as nostrils and mouth. This will allow us to build up a chronology of Oxford’s air pollution history with future implications for air quality. It will inform the development of healthy and sustainable cities, where stone sculptures may act as visible monitors of pollution.

The project team is made up of Jack Longman, Katrin Wilhelm and Scott Orr.

Further Information

Find out more about the Heritage Heads project.