What were early computers considered sensitive to?

Due to the huge number of heat-generating semiconductors and other components, mid '60s computers were kept in a VERY cool room to maintain an adequate temperature (typically 68 degrees F or so), with redundant air conditioners, in case one failed. Also, the huge disc drives that I saw had about 20" removable platters (a stack of 4-5 discs) as their storage discs. These were a whopping 40 Megabytes, as I recall. The washing machin-sized "Disc Drives" that held these massive platters HAD to have an excellent seal and vacuum system to keep dust particles out. The read/write heads floated so close to the discs that a particle of dust, or a smoke particle inside the drive could "crash" the heads. These were computers from about 1967 or so.