Left: number of statistically derived foreground stars as a function of Herschel column density expressed in A_K. The total foreground was identified as stars seen in projection against areas above a given threshold while showing negligible extinction. The field foreground was extracted from the Besançon model of the galaxy. The difference between those denotes the young foreground stars unrelated to the galactic field. The vertical dashed line indicates the optimal column density threshold for which background contamination is still negligible. Right: the given area on sky as a function of column density.