Rufus Stokes was born in Alabama in 1924. He later moved to Illinois, where he worked as a machinist for an incinerator company. In 1968, he was granted a patent on an air-purification device to reduce the gas and ash emissions of furnace and powerplant smokestack emissions. The filtered output from the stacks became almost transparent. Stokes tested and demonstrated several models of stack filters, termed the "clean air machine", in Chicago and elsewhere to show its versatility. The system benefited the respiratory health of people, but also eased the health risks to plants and animals. A side-effect of reduced industrial stack emissions was the improved appearance and durability of buildings, cars, and objects exposed to outdoor pollution for lengthy periods.
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