Measurements gathered by the Copernicus Sentinel-5P mission between January and August 2018 have been averaged to reveal formaldehyde in the atmosphere. This map is based on ‘vertical column’ concentrations. This air pollutant is released into the atmosphere from forest fires and wood processing, for example. It is an important intermediate gas in the oxidation of methane and other hydrocarbons. While it is short-lived in the atmosphere, it reacts chemically to become a major source of carbon monoxide – another harmful pollutant.