Distribution of (left to right) the H₂ volume density, gas kinetic temperature, the H₂CO column density, and the fractional abundance. The sources in Cygnus-X, the GLOSTAR pilot region, and M8 are shown in purple, orange, and blue across all distributions, respectively. Similar high-mass sources from the ATLASGAL Top 100, measured using higher J-transitions of H₂CO by Tang et al. (2018) are depicted in gray.