A fascinating study has shed light on air pollution in 12th century Britain. By taking ice cores from the Colle Gnifetti glacier in the Swiss-Italian Alps, it has been possible to use lasers to examine the air composition from 800 years ago by focusing on air bubbles trapped in the ice.
Analysing this data in tandem with atmospheric modelling, the study team has been able to identify a rapid build up in lead dust during the 12th century, which coincided with a lead mining boom in Britain. The particles are likely to have been swept across into Europe on the wind.
Lead had long been mined for its use in water pipe construction and the Romans, who were key proponents of this, were aware of the potential health risks associated with the metal. Mining of lead greatly expanded in Western Europe during the 11th-13th centuries as a pious church-building boom fuelled its use in ecclesiastical roofs and stained glass windows. Lead was also used in alchemy experiments and face whiteners (something that may have contributed to Elizabeth I’s death), as well as for adulterating wine. All healthy stuff.
An additional finding of this new research is how the levels of lead pollution in the atmosphere seem to correspond with significant political events. For instance, during times of upheaval (e.g. wars or the death of a monarch), the levels of lead pollution seem to have declined, suggesting a disruption in production.
One such dramatic event is interpreted to be the assassination of Thomas Becket. Becket was the archbishop infamously murdered in his cathedral at Canterbury after falling out with Henry II. Having served as the king’s chancellor, Becket was moved into the archbishopric by Henry, who was keen to limit the influence of the increasingly powerful Catholic Church and potentially siphon off some of its millions of acres of land.
Becket, however, was not about to abandon his religious duty and defied Henry’s wishes, prompting the king to utter the apocryphal plea: “Will no one rid me of this turbulent priest?” Of course he didn’t really say this but it makes for a nice story and whatever he did say, whether it was a direct order or a misinterpretation of a vague complaint, resulted in Becket’s bloody murder.
Becket’s martyrdom in 1170 coincided with a drop in lead pollution, at least so says the study, with pollution ramping up again a few years later, possibly due to Henry’s church-building surge to appease Rome after Becket’s murder had led to his excommunication.
Whilst the study doesn’t shed any more light on Becket’s actual death (despite the suggestion of a misleading title in the BBC article linked at the start of this piece) it is a good reminder that man-made pollution is not confined to the past couple of centuries.
Nor, despite its proven toxicity, has lead become a less desirable commodity. Indeed, global production has sky-rocketed in the past couple of decades, mainly a result of China’s massive increase in mining lead for use in electronics, machinery, chemicals, light industry and pharmaceuticals. It has created plenty of health incidents, albeit there are probably far more that have been hushed-up by Beijing.
It is already being said that the partial global shutdown prompted by Covid-19 is reducing pollution levels in the atmosphere, perhaps one of the few obvious benefits to spring from the pandemic as it moves into more vulnerable countries in Asia and Africa.
Perhaps in 800 years time some more enterprising scientists will look back at this moment in history and correlate the sudden dip in atmospheric pollution to a virus that was ultimately quickly consigned to the annals of time (we hope). That is, of course, if there is any ice left from which to obtain useful data.