Even if you were able to get out of the coffin without exhausting your air supply first, you’d find yourself in a situation similar to being buried in a mega-landslide or avalanche. The dirt would be so dense and heavy that your chest wouldn’t be able to expand. “It’d be like concrete setting in the course of seconds,” says Ethan Greene, Director of the Colorado Avalanche Information Center. Snow is heavy, but earth is even heavier. And if you were able to move, the dirt would fall into your mouth or nostrils and could end up clogging your airways.