Schematic evolutionary timeline of a star-forming region from the molecular cloud assembly until it becomes invisible in any of the three tracers we consider. In this study, we focus on the embedded feedback phase, during which stars are embedded within their host GMC. This phase is composed of an exposed phase, during which CO, 21 μm, and Hα emit simultaneously, and of an obscured phase, during which Hα emission is not detected. After the GMC dispersal, we measured an isolated phase of emission for both SFR tracers before they fade away. For most galaxies, 21 μm fades faster than Hα (upper arrow), but a few galaxies display a longer 21 μm emission (bottom arrow).