Condo collapse -when will the smell of decomposition start?

I know it sounds ghoulish, but I've witnessed rescuers in other hot/humid countries like the Philippines, Mexico and the WTC wearing masks while going through the rubble of a building. People think it's because of the dust or even the virus, but it reality, it's the odor of bodies decomposing. I would imagine no odor, no bodies. Am I right or wrong?