On Dust, Germs & Toilet Plumes
On Dust, Germs, and Toilet Plumes
by Angie Littlefield
I really, really don’t like germs, so you can imagine how I am dealing with the COVID-19 pandemic—not well!
It all started with a petri dish. In grade eight the teacher gave us a petri dish to label with our names and fill with a substance called agar. We set the dishes upon the wide, marble windowsill of the old school room and waited. In a day or two, tiny fly footsteps became visible in my dish, and, to my horror, mold overflowed the dish in a week. Other kids grew stuff beyond description and their goo materialized out of thin air.
Louis Pasteur and a lesser-known Hungarian scientist named Ignaz Semmelweis settled me down a bit in high school science. They made germs understandable and made me respect all the more the importance of hygiene. I came to see the merits of hand washing for those yucky, fly-riding, airborne things the teacher called germs. Only later did I learn that germs weren’t one homogeneous thing. Germs were bacteria, viruses, fungi, and protozoa—wee things that one needs a microscope to see.
Not seeing germs disquieted me then and still does. I’ve always felt it’s better to see things in order to face them. You can see dust and live comfortably with it. Catch the right sunbeam in your house and the motes dance before you. It can be pretty, even when you realize those fine particles are 50 percent dead skin cells and the rest a mélange of plant pollen, human and animal hair, textile fibers (like the lint in your dryer), paper fibers, and minerals stirred up from the soil. Just let the dust settle and wipe it away. If only it were that easy with those invisible germs. Where to wipe?
Recently the discussion about COVID-19 being airborne ratcheted up concern about danger in the air. We all want to understand how COVID-19 spreads to protect our families and ourselves. And yet, initial findings conflicted about whether the virus is airborne. One phrase in the cacophony caught my attention: “aerosolized particles.” We Silver Sagers are among the most vulnerable, so I decided to look into that. I found more than I bargained for.
We mostly think of aerosols as coming out of hairspray cans, not as something related to a virus. But the analogy of a can of hairspray is helpful to understand how microscopic particles of virus get into the air and onto objects. There are two main things to know about how aerosols work. If, for example, the mechanism in the hairspray can is clogged, then sometimes it lets out streams of spray and not puffs. The heavier droplets spread out and fall to the ground or onto nearby surfaces. Likewise, if an infected person coughs, the spray zone of their saliva is the air immediately around them and on the surfaces in the area in which their infected droplets land. Coughing, talking enthusiastically, laughing, breathing forcefully—these are all possible ways of creating an infected spray zone.
If your hairspray can is working well, however, then the buoyant force of aerolization produces a puffy emission with microscopic particles that stay suspended in the air for longer time periods. There is a much larger spray zone with aerolization. If the aerolized emission comes from an infected person then, as the aerosol part of the puff evaporates, the solid particulate of the virus floats free. It becomes light enough to be airborne and able to contaminate a much larger area.
Wearing masks, therefore, is doubly important. They not only help reduce the immediate spray zone, they also capture infected aerolized particles before they fan out more widely.
In people, a major culprit for aerolization is sneezing. Particles from a regular sneeze can reach a maximum of 200 feet and stay in the air for up to 45 minutes. Another major source of aerolization considered by scientists—long before COVID-19—was the toilet plume. When you flush the toilet, the bowl emits a stream of germ-filled particles of fecal matter, which has the potential to shoot 15-feet high. Back in 1975, Charles P Gerba[1] published a study in the journal of Applied Microbiology to warn that a single flush sent E coli bacteria airborne and made them viable for four to six hours. Toilets have improved since 1975, but aerosolized particles produced by flushing the toilet can still mix into the air, and the nuclei of the particulate may settle on nearby surfaces to coat them lightly with viruses seeking a host. If that toilet is used by several people, then anyone using it after that flush may be exposed to those aerosolized particles.
If you are not yet “creeped out” about these invisible things, consider that, in August 2020, the University of Arizona[2] found COVID-19 in the waste water (which is to say, sewage) of one of their student residences. The university took immediate action to test all 311 people in the dorm. They isolated two asymptomatic individuals and, by doing so, prevented the spread of COVID-19 within the building. Farther north, on October 14, 2020, the news from Ottawa, Ontario, was not as good. The waste-water tests for the previous several months showed an alarming rise in the levels of COVID-19 in the sewage of this city of 900,000. All this makes it abundantly clear that, when you flush, the toilet lid must first be put down.
I have made my peace with dust and have started routinely putting my toilet lid down. I am nevertheless as worried as I was in grade eight because we are not all acting upon the basic principles that even the ancients saw. The Greek historian Thucydides (ca. 460–ca. 400 BCE) wrote that disease could spread from one infected person to another. The Indian physician Sushruta (6th or 7th century BCE) theorized that infectious diseases spread by physical contact. The Persian physician Ibn Sina, known in the West as Avicenna (ca. 980–1037 CE), stated in Book IV of the al Qanun fi al-Tibb (The Canon of Medicine) that people transmit disease to others by breath. So, we have known this for a long while.
My position? Even though we don’t yet totally understand the spread of COVID-19, we all need to practice hygiene, social distancing, mask wearing, and putting down the toilet seat. Otherwise we will ourselves become the petri dish.
[1] Charles P Gerba, Craig Wallis, and Joseph L Melnick, “Microbiological Hazards of Household Toilets: Droplet Production and the Fate of Residual Organisms,” Applied Microbiology (now published as Applied and Environmental Microbiology), August 30, 1975, pp. 229–37
[2] Paulina Pineda and Rachel Leingang, “University of Arizona wastewater testing finds virus at dorm, prevents, outbreak,” azcentral, August 27, 2020
Photo by Giorgio Trovato (Walnut Creek CA) @giorgiotrovato
