Flux density of the detected HII regions from the A19 catalogue, as a function of their angular size. Known sources (K) refer to those with measured radio recombination lines (RRLs) or Hα emission. Groups (G) are HII region candidates located within the same complex as a known HII region. Candidate sources (C) are those co-spatial with radio continuum emission but lacking RRL or Hα detections. Radioquiet HII regions (Q) are those for which no radio continuum detection was detected in previous surveys.