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Potential Airborne Transmission; Hawaii and Air Purifiers. What does it mean?


Why not put portable air purifiers in classrooms, restaurants, medical facilities and care home to protect keiki and pupuna? Will they cause harm? No, so Why not error on the side of caution as we did with face masks.


The Scientific Brief below acknowledges potential airborne transmission, plus 40-45% of the folks transmitting the virus do not have symptoms. Portable air purifiers, since its purpose is to lower the virus load in the air. It’s simple and common sense. ~ Richard Ha


Excerpt from the SARS-Cov-2 and Potential Airborne Transmission Brief from the CDC Dated October 5th, 2020. Read the Full CDC Brief on their website.


The principal mode by which people are infected with SARS-CoV-2 (the virus that causes COVID-19) is through exposure to respiratory droplets carrying infectious virus.

Respiratory droplets are produced during exhalation (e.g., breathing, speaking, singing, coughing, sneezing) and span a wide spectrum of sizes that may be divided into two basic categories based on how long they can remain suspended in the air:

  • Larger droplets some of which are visible and that fall out of the air rapidly within seconds to minutes while close to the source.

  • Smaller droplets and particles (formed when small droplets dry very quickly in the airstream) that can remain suspended for many minutes to hours and travel far from the source on air currents.

Once respiratory droplets are exhaled and as they move outward from the source, their concentration decreases through fallout from the air (largest droplets first, smaller later) combined with dilution of the remaining smaller droplets and particles into the growing volume of air they encounter.


Respiratory viruses are transmitted in multiple ways

Infections with respiratory viruses are principally transmitted through three modes: contact, droplet, and airborne.

  • Contact transmission is infection spread through direct contact with an infectious person (e.g., touching during a handshake) or with an article or surface that has become contaminated. The latter is sometimes referred to as “fomite transmission.”

  • Droplet transmission is infection spread through exposure to virus-containing respiratory droplets (i.e., larger and smaller droplets and particles) exhaled by an infectious person. Transmission is most likely to occur when someone is close to the infectious person, generally within about 6 feet.

  • Airborne transmission is infection spread through exposure to those virus-containing respiratory droplets comprised of smaller droplets and particles that can remain suspended in the air over long distances (usually greater than 6 feet) and time (typically hours).

Droplet transmission consists of exposure to larger droplets, smaller droplets, and particles when a person is close to an infected person. Airborne transmission consists of exposure to smaller droplets and particles at greater distances or over longer times.

These modes of transmission are not mutually exclusive. For instance, “close contact” refers to transmission that can happen by either contact or droplet transmission while a person is within about 6 feet of an infected person.


The term “aerosol” has been used in various ways to describe small particles that can move through the air

Aerosol has been used both to define respiratory droplets of a certain size (e.g., smaller droplets and particles), as well as to describe the collection or cloud of these respiratory droplets in the air. In the healthcare setting, aerosol is used with respect to “aerosol-generating procedures” (e.g., intubation, bronchoscopy) that produce small droplets and particles and require distinct engineering controls to prevent occupational transmission of infectious pathogens like SARS-CoV-2. In community settings, aerosol was the term used to describe the sewage system-generated cloud of small droplets and particles that was believed to have spread SARS (caused by the virus SARS-CoV-1) during the 2003 Amoy Gardens outbreak in Hong Kong.


The term “airborne transmission” has a specialized meaning in public health practice

Airborne can be used to describe any size particle (e.g., droplet, dust, pollen) capable of travel through the air. For respiratory droplets, that can include droplets that are close to the source and those that have moved farther away. However, most infectious disease and public health experts reserve the term airborne specifically for use in the context of airborne transmission to describe infections capable of being transmitted through exposure to infectious, pathogen-containing, small droplets and particles suspended in the air over long distances and that persist in the air for long times.

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