The narrative of air pollution is revealed through the observations of ponds
Understanding historical air pollution could hold the key to explaining enduring health disparities across different regions of the UK. Paintings by renowned artists like Lowry, Constable, Monet, and Turner depict skies often obscured by haze and smoke, providing glimpses into past atmospheric conditions for which there are few direct measurements.
Dr. Ann Power from the University of Exeter has been investigating historical air pollution by analyzing sediment from urban and agricultural ponds, focusing particularly on the Merseyside region due to its industrial history and persistently high rates of chronic illness. She explained, "We aimed to track changes in urban air pollution over the last two centuries, observing how our towns and cities have evolved since the Industrial Revolution."
Historical investigations into air quality have required inventive approaches. Previous studies have examined soot deposits on stuffed birds in museum collections from the early 20th century, while others have analyzed 18th-century atmospheric electrical measurements by amateur meteorologists.
Dr. Power conducted her research by navigating small inflatable boats across ornamental and agricultural ponds depicted on 19th-century maps of Merseyside. These ponds, ranging from less than half the size of a football pitch to just a few meters across, offered insights into local air pollution history. Using ropes to anchor her boat in the center of each pond, she carefully drilled into the sediment.
Each pond revealed a unique narrative of surrounding air pollution, although overarching trends were evident throughout the region. Lead levels in pond sediments showed a sharp increase until the late 1990s when lead additives in petrol were phased out. Sulphur content declined from the 1970s onward, reflecting the implementation of smoke control areas and shifts from coal to fossil gas. Zinc and copper levels correlated with the rise of foundries and vehicle manufacturing. Fly ash particles mirrored the operations of former coal-fired power stations, such as those at Bold and Fiddlers Ferry.
One notable finding came from Oglet pond, situated near Liverpool's John Lennon Airport. Power observed changes in sediment magnetic properties since 1995, matching the particle types emitted from aircraft engines, coinciding with a tenfold increase in passenger numbers since the 1990s.
Across all ponds, a significant shift occurred in the 1980s with the emergence of smaller, combustion-derived particles, exposing populations to a new form of air pollution unprecedented in the preceding 150 years.
Professor Barbara Maher from the University of Lancaster, not involved in the pond study, emphasized, "The transition to smaller, metal-rich particles in recent decades poses particular health risks. Magnetite nanoparticles found in urban air pollution have been detected in human brains, hearts, and placental cells, suggesting a plausible biological pathway linking particulate air pollution to cardiorespiratory and neurodegenerative diseases."
Professor John Love of the University of Exeter warned, "While the visible pollution of the past has diminished, the shift to smaller particles means that air quality concerns persist, albeit less visibly. This study underscores the importance of not becoming complacent about air quality."
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