We now live in a world of masks and respirators. It is a world we are not prepared for largely
because the biomedical, sanitary, and technological advances of the last century left us accustomed
to breathing freely with little fear of what might be aloft in the air around us.
But because of COVID-19, N95 respirators and cloth masks—their availability and their
efficacy—now dominate the news and are at the heart of often vitriolic public debates.
Both futuristic and somehow archaic at the same time, millions now depend on their use
to prevent infection of a potentially deadly illness.
The respirator and the cloth mask emerged during the nineteenth century and each has
been shaped by our shifting understandings of how disease factors work in the first place.
As a general rule, respirators function by filtering out harmful material before it enters
your lungs while masks keep you from spreading infectious agents to others.
English physician Julius Jeffreys first patented the respirator for the treatment of chronic
throat and lung diseases in 1836. Made of silk, leather, and layers of wire mesh, the
respirator trapped heat and moisture. This served to loosen the mucus membranes and provided
a comforting insulation from the cold, allowing the wearer to breathe more easily.
Jeffreys began his medical career in India, where he observed that the extreme heat and
humidity of lowland Bengal took a physical toll on the soldiers and officials of the
East India Company. Upon returning to England, he observed that Europe’s colder, drier
climate seemed to contribute to his sister’s severe asthma symptoms.
Jeffreys’s respirator provided a means of engineering what he referred to as “a local
artificial climate” to open air passages in the throat and lungs. Jeffreys was so deeply
committed to climate’s role in disease that he rebranded his respirator as a “climatic
apparatus” in 1864. His respirator was advertised directly to
consumers and became immediately popular with the British public. Victorian writer Jane
Welsh Carlyle adored her respirator. In a letter to her mother, Carlyle claimed the
device had “the property of making all the air that goes down one’s throat as warm
as summer air.” Despite its odd look (roughly resembling a dog’s muzzle), Jeffreys’s
invention clearly had a therapeutic effect. Jeffreys’s assertion that climate was responsible
for disease was controversial. Many adhered to the belief that disease came as a result
of airborne poisons from the decomposition of human and animal waste. This Miasma theory
held that diseases drifted through these malodorous clouds and periodically afflicted populations
with diseases like cholera. Filtering these gases became the principle
of a new kind of respirator. The “Inhaler” or “Lung Protector” was first patented
by American Lewis Haslett in 1847. Scottish chemist John Stenhouse developed his own charcoal
respirator shortly thereafter. Stenhouse had studied the use of charcoal as a means to
filter toxic gases from London’s sewer systems. Fitted to the face, the charcoal respirator
was designed to adsorb harmful particles suspended in air, protecting the wearer from miasmic
illness. Stenhouse’s filtration approach gradually superseded Jeffreys’s design and
formed the basic principle of the contemporary purifying respirator. Unlike Jeffreys, Stenhouse
refused to patent his invention and vowed to make his innovation available to everyone
at the lowest possible price. The emergence of the germ theory of disease
later in the nineteenth century superseded the miasma theory. After experiments by Louis
Pasteur and Robert Koch, among others, it became increasingly clear that diseases were
caused by microscopic pathogens. The emergence of the germ led to a gradual
decline in the use of the respirator as a health aid for the public at large. However,
germ theory helped to usher in the widespread use of cloth masks.
Studies of human saliva showed a multitude of bacteria capable of being spread to patients
by doctors performing surgery. Simpler than the Victorian respirators, cloth masks proved
effective in stopping the spread of infection when used by doctors.
Cloth was used for makeshift masks during the Third Plague pandemic in China in 1911.
Evidence showed that cloth covering could prevent the spread of the pneumonic plague
through coughs. The Spanish Flu of 1918 saw wide use of cloth masks around the world to
prevent infection through the control of droplets emitted by coughs and sneezes.
Respirators did not disappear. The technology to filter chemical contaminants
eventually developed into the gas masks of World War I. Over the twentieth century, gas masks
were called upon to filter all manner of harmful particles encountered on the battlefield environment
resulting in CBRN, chemical, biological, radiological, nuclear, or NBC, nuclear, biological, chemical,
personal protective equipment. Personal filtration was also widely employed in the mining and
chemical industries. The N95 respirator, which has been much in
the news recently, became the industrial filtration standard in the 1970s, rated to filter 95%
of harmful particles. The N95 uses polypropylene fibers to filter the COVID-19 virus suspended
in air within hospital wards and other high-risk areas. These respirators must be regularly
replaced to be effective. Columbus, Ohio-based company Battelle has recently developed means
to safely decontaminate and reuse N95 respirators utilizing ultraviolet light.
The everyday cloth mask is not primarily intended to filter the environment outside, but rather
serves as a simple means to keep the source of disease inside the wearer thus preventing
its transmission to others. The cloth mask’s role is essentially droplet
control. By keeping sneezes, coughs, and other liquids confined to oneself, the cloth mask
allows the wearer to breathe while creating a barrier preventing the virus to move to
other hosts. Studies have consistently shown that even the modest cloth mask has a significant
effect in preventing the spread of respiratory diseases to others.
The best way to mitigate the problem of COVID-19 continues to be social distancing. However,
our networks of infrastructure, supply, and distribution are deliberately designed to
bring people together in confined spaces. The efficiency gained from concentrating human
beings on public transport, in warehouses, and offices now works to help the coronavirus
spread. Many cannot work from home and must place
themselves at risk. So until a vaccine is developed, it is essential that those exposed
to the virus—like health care workers—continue to wear respirators while the rest of us need
to wear our masks to keep the disease from spreading.