Next generation ice core technology reveals true minimum natural levels of lead (Pb) in the atmosphere: insights from the Black Death

Current policies to reduce lead pollution in the air are based on the assumption that pre-industrial levels of lead in the air were negligible, safe or non-existent. This trans-disciplinary article shows that this is not the case, using ‘next-generation’ laser technology in climate science, in combination with detailed historical and archaeological records in as many as 7 languages, from all over Europe. We show that lead levels in the air have been elevated for the past 2000 years, except for a single 4-year period. This 4-year period corresponds with the largest known pandemic ever to ravage western Europe (the Black Death), resulting in a 40-50% reduction in population. This unprecedented historic population collapse was accompanied by dramatic economic collapse that halted lead mining and smelting, and related emissions in the air. This trans-disciplinary study is a collaboration led by Harvard University and the Climate Change Institute at the University of Maine, and researchers from the University of Heidelberg (Germany) and the University of Nottingham (UK). It uses next-generation technology and expertise in history, climate science, archaeology and toxicology, brought to bear in a highly detailed contribution to planetary health, with crucial implications for public health and environmental policy, and the history of human exposure to lead.