Failure of the pressurization system and the resulting decompression can produce significant problems for those on board. Slow decompression of the cabin is dangerous because of the insidious onset of hypoxia, while rapid decompression presents dangerous physiological risks.
A number of factors control the rate and time of decompression. The larger the cabin area, the slower the decompression time. The larger the opening, the faster the decompression. And the larger the pressure differential between the outside atmosphere and the cabin interior, the more severe the decompression, which in general explains the rapid type of decompression more common at higher altitudes.