A couple of weeks ago the United States' CDC was the center of a brouhaha over its retraction of a statement that SARS-CoV-2 (hereafter will be referred to as 'COVID-19') may be aerosolized. In the words of the New York Times, W.H.O "persists in its reluctance" to accept aerosolized COVID-19 as a means of transmission. Yet, within the professional community--those who work with and around the virus, alerts are issued about the danger of COVID-19 transmission through contact with aerosolized particles.
An Aerosolized Particle
Image credit: Dr. Sahay used under CC 3.0 license.
This picture shows what the author calls a common bioaerosol. An aerosol is a "suspension of fine solid particles or liquid droplets in air or another gas". A bioaerosol consists of "both living and non-living components, such as fungi, pollen, bacteria and viruses". Aerosols travel easily on air currents.
COVID and Aerosols
It has been established that different types of corona virus (though not necessarily COVID-19) can be, and are, transmitted through aerosols. If it is determined by W.H.O. and the U. S. CDC that COVID-19 can be transmitted by aerosols, then a whole new set of costly and inconvenient mitigation protocols will have to be recommended. PPE will have to be enhanced, because aerosols can easily penetrate an ordinary surgical mask. Distancing, ventilation, sterilization regimens will be strengthened, because aerosols travel further than droplets and hang around longer.
HEPA Air Filter
Image Credit:Hardyplants. Used under a CC 1.0 Universal license.
HEPA filters are designed to filter 95% of aerosols with a "diameter between 0.25 and 1.0 μm and nearly 100% for those with diameter larger than 2.5 μm that are .25". According the journal Building and Environment, SARS COVID-19 aerosols fall within this target size.
Aerosols and the Drain Pipes
While a variety of institutional actors (as cited above) have resisted the notion that COVID-19 can be transmitted by aerosols, there's a body of research that asserts the opposite. Not only does this research confirm aerosolization of COVID-19, but it also asserts that common bathroom activities may spread COVID-19. Also, that exposure to contaminated bathroom drains is dangerous.
Image credit: Jadon Kelly on Unsplash
A 2006 paper outlining drain pipes as a route of transmission for COVID-1 (SARS) was published in the Journal of Environmental Health. The article describes an outbreak in a Hong Kong private apartment complex, the Amoy Gardens. In that event, the virus accumulated in the pipes, dried, became aerosolized and spread through the building.
Three hundred and twenty-one people were sickened in this episode. Forty-two of these people died. According to the Environmental Health article, viral aerosols "were drawn into apartment bathrooms through floor drains" and then dispersed in the air. Some airborne dispersal even occurred to a neighboring building.
Image credit: WMwiki. Used under CC 3.0 license.
Selected Literature on Drain Pipe Transmission of COVID-19
Healio Primary Care, (a journal for medical professionals): Study Finds Evidence of Fecal Aerosol COVID-19 Transmission
This article describes a scenario that mirrors the 2003 SARS outbreak at Amoy Gardens. In January and February, 2020, three families in a Guangzhou (China) apartment complex were infected with COVID-19. However, only one of the families had had direct exposure to the virus--they had traveled to Wuhan. The only connection between the three families was the drain pipes they shared.
Investigators released a tracer gas into the pipes that connected their toilets. Following the path of gas the researchers determined the virus had spread through the pipes to families who lived in the same vertical stack. The conclusion: fecal aerosols were distributed up the plumbing stack when a toilet was flushed after being used by an infected person.
Body temperature retest area in Guangzhou subway station, 8/2020
Image credit: David290. Used under CC 4.0 license.
The Lancet Global Health: COVID-19 Mitigating Transmission Via Wastewater Plumbing Systems
This article explains that plumbing, by its very design, harbors pathogens. Under certain circumstances plumbing can "enable airborne transmission of viruses such as...(SARS-CoV-2).." The article goes on to explain that in a hospital, those special circumstances exist because, "Self-isolation can lead to a greater number of infected people in a building..." Also that, using hospital wards to quarantine causes "concern because of the interconnectedness of the whole system".
Patient Suite at Birla Hospital for Women, India
Image credit: The So So Guy. Used under CC 4.0 license
FacilitiesNet (a journal for the building management industry): Minimizing Coronavirus Transmission through Hospital Mechanical and Plumbing Systems. Steps to consider include isolation rooms, HEPA filtration, UV lights, increased humidity, use of 100 percent outside air, and keeping hot water systems balanced and flowing.
This article cites information from the World Health organization that: "there is a possibility for contamination through floor drains or like fixtures".
The International Association of Plumbing and Mechanical Officials Guidelines to Protect Workers Related to Coronavirus (COVID-19)and Other Potential Infectious Materials (OPIM)in Plumbing and HVAC Systems
This article issues the following blunt cautionary statement for those who work in the plumbing industry during the COVID-19 pandemic: "...it should be assumed by anyone working on a sanitary drainage system that the virus is present.” The authors recommend the use of protective equipment when working in affected areas. This equipment includes: "full face shield worn over safety goggles, impermeable gloves, and protective clothing..." This notice ends on this sobering note: "Assume that everything inside that system is contagious".
This essay has been an attempt to consider, very briefly, potential aerosolization of COVID-19. I've consulted numerous responsible sources and pieced together a case, I believe, for aerosolization--despite W.H.O's reluctance, and the U. S government's reluctance, to affirm this. I think we might extrapolate from aerosols produced in drain pipes to aeorosols produced in other environments. It does seem logical to make this leap. Certainly, given the high stakes (risk of getting COVID-19), it would seem reasonable for most of us to behave as though COVID-19 aerosols exist.
***Illustration at the top of the page: ***
Pipe adapted from Pixabay