Wow, nice connection! ;) Dr Wu's design is the ancestor of the modern respirator...
The N95 is made for industries but arrives just in time to hospitals
The N95 mask is a descendant of Wu’s design. Through World War I and World War II, scientists invented air-filtering gas masks that wrapped around your entire head to clean the air supply. Similar masks, loaded with fiberglass filters, began to be used in the mining industry to prevent black lung.
“All the respirators were these giant, gas mask-looking things,” says Nikki McCullough, an occupational health and safety leader at 3M, which manufactures N95 respirators. “You’d wash them out at night and you could wear them again.”
This equipment saved lives, but it was burdensome, and a large reason why were the filters. The fiberglass required a lot of effort to breathe, and the full head enclosures were hot to wear. By the 1950s, scientists began to understand the dangers of inhaling asbestos, but people working with asbestos preferred not to wear bulky respirator masks. Imagine working in construction in 85-degree heat and having your head wrapped in rubber to protect yourself from an invisible threat.
So in the 1970s, the Bureau of Mines and the National Institute for Occupational Safety and Health teamed up on creating the first criteria for what they called “single use respirators.” The first single-use N95 “dust” respirator as we know it was developed by 3M, according to the company, and approved on May 25, 1972. Instead of fiberglass, the company repurposed a technology it had developed for making stiffer gift ribbons into a filter, by taking a melted polymer and air-blasted it into layers of tiny fibers. “They look like somebody dropped a bunch of sticks—and they have huge spaces between them,” says McCullough.
As particles, whether silica or viruses, fly into this maze of sticks, they get stuck making turns. 3M also added an electrostatic charge to the material, so even smaller particles find themselves pulled toward the fibers. Meanwhile, because there are so many big holes, breathing is easy.
The longer you wear an N95 respirator, the more efficient it becomes at filtering out particles. More particles just help filter more particles. But breathing becomes more difficult over time as those gaping holes between the fibers get clogged up with particles, which is why an N95 respirator can’t be worn for more than about eight hours at a time in a very dusty environment. It doesn’t stop filtering; it just prevents you from breathing comfortably.
N95 respirators were used in industrial applications for decades before the need for a respirator circled back to clinical settings in the 1990s with the rise of drug-resistant tuberculosis. HIV had a lot to do with its spread across immunocompromised patients, but tuberculosis infected many healthcare workers, too. To stop its airborne spread, N95 standards were updated for healthcare settings, and doctors began wearing them when helping tuberculosis patients. Even still, respirators are rarely used in hospitals to this day because it’s only outbreaks like COVID-19 that necessitate so much protection.
As Lynteris and many others point out, the respirator never really faded from significance in China. Wu went on to found China’s version of the CDC, narrowly miss winning a Nobel Prize, and be featured in many biographies (including his own autobiography). More recently, during the SARS outbreak, people in China wore facial protection to prevent the spread of illness. Then as pollution took over cities like Beijing, they wore respirators to filter pollution.
Source: fastcompany.com |
