The enemy was very small but it was everywhere. World peace, medical advancement, iTunes — all would eventually be threatened.

Half a century ago, as a rapidly changing world sought increasingly smaller mechanical and electrical components and more sanitary hospital conditions, one of the biggest obstacles to progress was air, and the dust and germs it contains.

Stray particles a few microns wide could compromise the integrity of a circuit board of a nuclear weapon. Unchecked bacteria could quickly infect a patient after a seemingly successful operation. Microprocessors, not yet in existence, would have been destroyed by dust. After all, an average cubic foot of air contained three million microscopic particles, and even the best efforts at vacuuming and wiping down a high-tech work space could only reduce the rate to one million.

Then, in 1962, Willis Whitfield invented the clean room.

“People said he was a fraud,” recalled Gilbert V. Herrera, the director of microsystems science and technology at Sandia National Laboratories in Albuquerque. “But he turned out to be right.”