Ever since a fire devastated the Notre-Dame de Paris cathedral in April 2019, locals and environmental groups have raised concerns about the fate of lead in the cathedral’s roof and spire. Alexander van Geen of Columbia University set out to determine if those fears were justified. In December 2019 and February 2020, van Geen collected multiple samples of soil near the cathedral and measured lead concentrations via X-ray fluorescence. Statistician colleagues then used these measurements to estimate how much lead fell near the fire. Their results suggest that about 1,000 kg of lead settled within a kilometer of the cathedral—more than six times the amount estimated by local authorities (GeoHealth 2020, DOI: 10.1029/2020GH000279). Van Geen’s tests show that lead-laced dust settled in the area and may have also got into buildings. According to the US Centers for Disease Control and Prevention, ingesting contaminated house dust or soil is one way children become exposed to lead. Larger environmental tests immediately after the fire would have alerted health officials to the dangers, the researchers say. But few samples of soil, dust, or blood were collected immediately after the fire, making it difficult to ascertain how the lead from this event may affect human health.