2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/4386We have observed extended emission physically associated with 15 out of 16 UC HII regions with large ratios of single-dish to VLA fluxes. We discuss their implications for the age problem of UC HII regions and the evolution of HII regions.2 pages, To appear in Hot Star Workshop III: The Earliest Phases of Massive Star Birth, ASP Conference Series, 2002, ed. P. A. CrowtherAstrophysicstext