No computers or medicine without HEPA filters

The HEPA filter technology actually makes it possible for you to read this article about the
history and facts about HEPA filters. Producing the semiconductor chip that you have in
your computer, phone or tablet, is a highly sensitive process. The chip has to be fabricated
in clean rooms where HEPA filters ensure the air contains less than 1 particle per cubic foot.   

As a comparison, most common indoor spaces have hundreds of thousands of air particles per
cubic foot.

In addition to the microelectronics industry, where they manufacture computer chips, HEPA filters
are also used in clean rooms in the pharmaceutical industry and the food and beverage industry.
Other examples of where HEPA filters are essential are operating rooms in hospitals, research
laboratories and nuclear power plants.

It started with a gas mask

The origins of the HEPA filter go back to the early days of the Second World War, when a British
soldier found a piece of paper that was part of a German gas mask canister. The British military
had the paper analysed and found it to be remarkably effective in capturing chemical smoke.
The British Army Corps was then able to replicate the paper so it could be incorporated into gas
masks for the British armed forces. 

However, a solution was also needed for protecting military staff in operational headquarters,
where it was impractical to wear gas masks. A combined mechanical blower and air purifier unit
- called the collective protector - was therefore developed by the British Army Chemical Corps.
It was equipped with a cellulose-asbestos paper in deep-pleated form with spacers between the
pleats. The paper was referred to as an Absolute air filter and it was the precursor to what would
later become the HEPA filter. 

Connected to the first atomic bomb
​

The next step in the evolution of the HEPA filter took place a few years later. In August of 1942,
the United States began the Manhattan Project in Oak Ridge, Tennessee, which led to the
development of the first atomic bomb. 

The Manhattan Project involved 90.000 workers and they needed to be protected from hazardous
radioactive air particles that were emitted during the development and manufacturing of the atomic
bomb. This prompted the U.S. Army Chemical Corps to initiate a secret project where they used
the knowledge and insights from the British gas mask and Absolute filter project to try to develop
an air filter that could remove radioactive particles from the air.

They collaborated with Nobel Laureate Irving Langmuir, who helped specify that particles of 0.3 microns
in diameter were potentially the most important to capture. The result became the first HEPA filter
(it was not called HEPA until the 1950s). 

The only problem was that the Manhattan Projects’ version of the HEPA filter could not effectively
reduce the impact of radioactive radiation. But it did offer excellent protection against mustard gas,
chlorine gas and noxious gases from flamethrowers.

Permitted for commercial use
​

In the 1950s, the HEPA filter technology was declassified and commercialised and the term “HEPA”
became a generic trademark indicating highly effective air filters. 

It would take until the 1960s for the HEPA filter to be fully commercially viable thanks to the rise of
the microelectronics industry and also the nuclear power industry.

All filters called HEPA are not HEPA
 

The term “HEPA” has often been misused in consumer marketing of, for example, vacuum cleaner
filters, water filters and filters for residential boilers. These filters fail to meet the industry definitions
and the required minimum 99.97% efficiency at 0.3 microns and are therefore not HEPA filters.