Upper panel: all-sky map of the number of C3PO Planck cold clumps per sky area (2° × 2°). The ECC sources are overlaid as blue squares. Middle panel: contours of ¹²COJ = 1 → 0) line emission (0.1, 1, 4, 10, 30 Kkms^-1) are over-plotted on the C3PO density map, which is set to zero where the CO map is not defined (limited by the blue contours). The resolution of the CO map is 2°. Lower panel: visual extinction contours (A_V = 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7 mag) are over-plotted on the C3PO density map, which is set to zero where A_V is lower than 0.1 mag (blue contours). The A_V map is also at a resolution of 2°.