A Brief History of Home Air Purification — the Early Years

The first residential air purifier was released in 1963. But what did people do before then? Let’s explore the history of home air purification before the modern era.

Prior to domesticated animals and large cities, communicable diseases could only cause so much damage. But carbon monoxide, carbon dioxide, and particulate matter from the hut’s fire pit was an immediate threat. In time out of mind, ancient people learned to cut a hole in the roof for ventilation. Improvements in ventilation and source control were the only forms of air purification available for millennia. Considering the high rate of lung disease found among ancient Egyptian mummies, the earliest versions of these methods were of limited effectiveness.

According to the ASHRAE Journal, Ancient Romans developed floor radiant heating and smokestacks to improve the air in wealthy and urban dwellings. The smokestack’s more bucolic cousin, the chimney, arose in the 12th century, allowing for the heating of multiple-story dwellings. Further attempts at smoke removal came in 1600 when King Charles I of England “decreed that no building should be built with a ceiling height of less than 10 ft (3 m), and that windows had to be higher than they were wide.”

In either the Middle Ages or the Early Modern Period (sources differ), people first began to notice that indoor air could transmit disease, especially in crowded conditions. Often, they falsely believed that this was transmitted through odors (“miasma”), resulting in attempts to purify the air by burning herbs or wearing bunches of flowers near the mouth and nose (“posies”). However inadvisable, these methods were an early attempt to expand the technological options available.

The scientific method allowed humans to refine their understanding of indoor air quality; Per ASHRAE, a 17^th century scientist named Mayow noticed that small animals enclosed in a bottle with a burning candle asphyxiated more quickly than those without. In 1775, Lavoisier identified carbon dioxide as the culprit of this premature demise.

In 1886, Pettenkofer theorized that biological contaminants may also contribute to bad air but still held that carbon dioxide measurements were a reasonable stand-in for air quality. From the mid-1800s onward, ventilation efforts attempted to balance minimizing carbon dioxide, minimizing the spread of disease, and maximizing comfort.

In the late 1800s, the first modern air purification technologies appeared — not for homes, but for industrial workers. Multiple inventors attempted to patent various devices to protect workers from the sundry chemical fumes of the Industrial Revolution. Most were clumsy respirators, but John Stenhouse’s 1860 patent foreshadowed one component of the modern home purifier — an air filter made from charcoal (i.e. activated carbon).

In 1877, scientists noticed that sunlight impeded microbe growth, which was the first step towards developing UV purification. Small electric fans — later to become essential to modern purification — appeared a few years later.

Despite the development of gilded-age gas masks, ventilation remained king at the dawn of the 20th century. By the early 1900s, 22 states had building codes requiring a ventilation rate of 14 L/s. The fact that victims of the 1918 Flu Pandemic tended to survive better outdoors further boosted the push for better ventilation indoors. By the 1930s, hospitals and schools began to experiment with UV purification, but this development still hadn’t reached the home.

That brings us to the strange case of fibrous air filters. During World War II, the Allies discovered a German gas mask canister containing an odd slip of paper. This paper had a remarkably high efficiency for capturing chemical smoke, prompting the US Army Chemical Corps to reverse-engineer it. These early precursors of HEPA were called “absolute filters”; unlike HEPA filters, absolute filters were made from asbestos and cellulose. However, the military didn’t just use these new absolute filters in gas masks. According to Dr. Melvin W First’s history of HEPA filters:

“Protection against warfare agents was also required for operational headquarters, where the wearing of an individual gas mask is impractical. For these situations, the Army Chemical Corps developed a combination mechanical blower and air purifier unit known as a ‘collective protector.’ As relatively large air flows were required, the filter[…]was fabricated into a deeply-pleated form with spacers between the pleats to keep them apart and serve as air passages.”

This collective protector may have been the first instance of a fibrous filter air purifier.

Army funding was also responsible for the discovery that particles around 0.3 microns wide are the most difficult to capture, making 0.3 microns the standard for fibrous filter testing.

In 1952, the absolute filter was declassified, giving residential spaces their first new purification technology since ventilation. Improvements in fiberglass technology allowed fibrous filters to abandon asbestos (phew!), making them practical for regular use.

Manfred and Klaus Hammes were the first to release a home HEPA purifier in 1963, but they weren’t the last. Despite being an 80-year-old technology, HEPA is still standard in most models of home air purifiers (including ours).

However, why should one be satisfied with World War II II-era technology alone? Activated Carbon and UV would also eventually make their way into the home, but these technologies are only effective against certain contaminants. Perhaps it’s time — not to replace older technology — but to support it with more recent innovations.

For instance, the Wisconsin Center for Space Automation and Robotics developed a method to scrub VOC gases from the space shuttle in 1995. It turned out that this technology could also inactivate pathogens in the air and on surfaces. After 22 years of refinement, and tens of millions of dollars in R+D and validation testing, ActivePure’s Advanced Photohydrolysis was born.

Like HEPA, Advanced Photohydrolysis originated in a partnership between private and public research. Like HEPA, it was improved over 2 decades. Thus, ActivePure’s origins are just as prestigious as the HEPA filter’s…but far more recent. To learn more about our bonafides, visit our history page.