The Origins of the HEPA Filter: Nuclear Research

There has been some… grim news recently about a possible war between the US and North Korea over their developing nuclear capabilities. There is a ray of light though, in this grim news. It gives us an excuse to talk about HEPA Filters. It turns out, they were created specifically because of nuclear research and the fall out of nuclear weapons.


Filters Before HEPA

Air filters have been around for a long time. The first air filters can be traced all the way back to the 1500s, a primitive respirator to protect the wearer from gases, dust, and fumes. Damp-cloth respirators started to come around in the 18th and 19th century. These used damp wool and valves to filter dust out of the air. The liquid-based approach would end up expanding to water and oil bath systems that essentially washed the air. Most contaminants would end up dissolved or pushed down in the water, while the air could eventually pass through.

This technology was used on cars, trucks, tractors, and even some early air conditioning systems. It was pretty much the only known way to clean the air. At the time, there were no electron microscopes and the concept of cells and bacteria was still pretty new. There simply hadn’t been research into all the little things in the air and how effective or ineffective the existing filters were beyond subjective opinions.

In the 1940s, there came a very strong incentive to study, invent, and build better filtration technology.


High Efficiency Particulate Air Filters

During the 1940s it became apparent that oil and water bath filters wouldn’t cut it for the Manhattan Project. The radioactive materials inherently emit tiny particles of radioactivity. These are alpha and beta particles. They could burn your skin  or just destroy your body from the inside out. Then there was the risk of fall out from a nuclear blast. No detonation would actually use all of the nuclear fuel. Chunks of radioactive, decaying plutonium and uranium would rain down from the sky, particles smaller than what current filters could handle. We needed a highly efficient, particulate filter.

The greatest challenge was that you couldn’t weave a filter with threads that dense. The technology to manufacturer threads with nanometer scale accuracy didn’t exist then and probably isn’t an affordable concept even today. However, by layering and properly arranging materials, the chances of particles getting through are reduced. The particles would have an ever greater chance of colliding with something, getting stuck, or even bouncing off the filter’s internals and wandering forever inside it.

With the immense resources of the war effort, the new filtration technology was invented. It was now possible to remove microscopic particles from the air. This was a huge development. Up until this point in history, filtration tech had been spotty at best. Now however, it was possible of stopping pathogens, contaminants, allergens, and more.

After the war, the technology would be shared with the public. Arguably, this was a necessary safety measure with the looming cold war as much as it was a necessary step to improve the health of the country at large. If nuclear war broke out, as many people in the US would need the HEPA filters as could be made. If nothing came of nuclear war, the widespread use of the filters would prevent the spread of disease and enable such developments as the first clean rooms. It was a secret too good to keep.


Spreading the Safety

Once the HEPA technology was lose in the wild, it became an essential part of every day life. Hospitals, factories, businesses, and even regular home owners all started buying stuff with the better filters. It wasn’t an overnight process, but over the decades it became the standard.

The Wrap Up

What did you think? Did we get something wrong? Got something for us to cover next time? Let us know in the comments below.


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