Circles indicate where discrete soil samples were collected and are colored according to their lead content in milligrams per kilogram of soil (mg/kg, also referred to as parts per million or ppm). Hovering over a circle displays a photo of the sampling site marked by a paper bag along with the sample ID, measured lead concentration, date of collection, sample type, and GPS coordinates.

Clicking on ‘Predicted Values’ displays a layer of colored tiles that show the continous distribution of lead modeled from the data. Hovering over a tile displays the modeled mean lead concentration across that area as well as the 10% and 90% quantile to represent the range of possibilities. The model predicts that 1 in 10 actual measurements of lead concentrations in that tile would fall below the 10% quantile value, and that 1 in 10 would surpass the 90% quantile value. The uncertainty represented by the range of lead concentrations between the 10 and 90% quantile varies considerably across the area and generally decreases with the density of samples.

Full research article: "Fallout of Lead over Paris from the 2019 Notre‐Dame Cathedral Fire" by Alexander van Geen, Yuling Yao, Tyler Ellis and Andrew Gelman. Map: Jeremy Hinsdale.

Usage: Hover over map features for location information; mouse wheel to zoom, drag/drop to move.