"So this was maybe nine months after the fire in Notre Dame, and I had been struck visually by the fire, the yellow smoke, which is a telltale indicator of lead. The fact that 400 tons of lead constituted the covering of the roof of the cathedral. And a lot of that had volatilized, presumably, but no one really knew how much. So that got me thinking, and I happened to be in Paris at the time, so I thought if it's so much lead, could it be that it affected the population living within say a kilometer of the cathedral? I thought there wasn't really a lot of clear information about what had happened, and what had been measured. I thought some more openness and transparency was needed."Geochemist Lex van Geen is a research professor at Lamont-Doherty Earth Observatory and is member of the Earth Institute at Columbia University. His research focuses on ways to reduce the impact of the environment on human health. For two decades, he coordinated earth-science on the origin and health effects of elevated levels of arsenic in groundwater. His other projects focus on fluoride in groundwater in India, bauxite dust in Guinea, or soil contaminated with lead from mine-tailings in Peru, and fallout of lead over Paris following the fire in Notre Dame. Dr. Van Geen is a firm believer in the more widespread use of field kits by non-specialists to reduce exposure to environmental toxicants.www.ldeo.columbia.edu/~avangeenwww.oneplanetpodcast.orgwww.creativeprocess.info