You may not know it, but HEPA filters were originally classified as top-secret, developed by the US Atomic Energy Commission to protect soldiers from radioactive particles on the battlefield. During World War II, scientists involved in the Manhattan Project used HEPA masks to guard against contaminants from the atomic bomb.

Although these early HEPA masks couldn’t possibly protect people from atomic radiation, the research spawned the HEPA filter, which provided protection against chlorine gas, mustard gas, and flame throwers. It was not until the 1960s that specifications were standardized and the term HEPA or "High Efficiency Particulate Air" was officially coined by the Department of Energy (DOE).

As defined by the DOE, HEPA filters remove at least 99.97% of dust, pollen, mold, bacteria and any airborne particles with a size of 0.3 microns at 85 litres per minute. From the beginning, HEPA filters were employed to filter out highly hazardous aerosols, toxic carcinogens, radioactive particles, and biohazardous contaminates.

Meanwhile, across the world in Germany, brothers Klaus and Manfred Hammes purchased a patent for a simple air filtration system. Using a fiberglass pad attached with small magnets to the air outlet of a residential oil oven, the Hammes brothers were able to filter soot from the air. In 1963, the Hammes brothers’ simple but effective filter became the first air cleaner to be utilized in homes across Germany.

Coincidentally, in the same year, US Congress passed the Clean Air Act of 1963 to set standards for the reduction of air pollution through fuel emissions standards. Although it was not Congress’s first attempt at reducing air pollution, the Clean Air Act of 1963 alerted scientists and consumers of the need to protect our lungs from pollutants such as perfumes, building materials, chemicals, pesticides, and allergens.