How Diseases Spread Through the Air and Surfaces

When someone first explained to me that most germs are transmitted by ingesting an infinitesimally small amount of fecal matter, or rubbing someone else’s bodily fluids into your eyes, nose, or open wound – I had the same reaction as you. Gagging.

It is so hard to believe that such a thing could even be possible. So how exactly do germs, such as bacteria, viruses, and fungi, spread?

Airborne germs

Some germs, or microbes, infect the lungs and when we cough or sneeze, they ride those droplets out of our bodies and into the air. Good examples include coronavirus, Influenza, and RSV. But the question is, unless I’m standing there with my mouth wide open, how did it get inside me?

When we think about respiratory droplets, we are incorrectly only considering those we can see and feel – tiny gross droplets of saliva or mucus. But recall how you can gently exhale to mist your reading glasses, fog a cold car window to draw a smiley face, or simply generate your own personal cloud on a cold winter’s day? Just one single breath contains millions of respiratory droplets. If we breathe repeatedly on a cold surface, they will eventually accumulate and form a droplet, and we have transformed the microscopic to the macroscopic.

Here is the disease part. Many of these microscopic respiratory droplets are about 3-5 times the size of a bacterium or virus, and happily carry those germs into the air. They are so incredibly light; they remain suspended in the air. Afterall, they are much smaller and lighter than dust and we are used to see those floating in the air lit up by a sunbeam.

All that is left is for me to inhale. And when I ingest enough particles, a threshold called the minimum infectious dose, the germs take hold and develop into the disease. This is what they mean by an airborne transmitted disease.

That explains the mouth and nose. But what about the eyes? While our skin is incredibly effective as a suit of armor, mucous membranes around the eyes are more vulnerable and germs can get through. For example, after swimming in public or private pools, we’d like to believe red stinging eyes and the ‘smell’ of swimming pools was a result of excessive chlorine. According to the CDC, it is due to pee, poop, sweat, and dirt from other people’s bodies.

So yes, your eyes, nose, and mouth are vulnerable to germs. They linger in the air, suspended like microscopic dust particles just waiting for you. That is why high-quality HEPA air filters are your first line of defense.

You can also place Ultraviolet C (UVC) units inside your ductwork to process contaminated air as it flows past. But UVC units only have a split-second to irradiate the passing air, and it needs much longer. To be effective the air would have to spend anywhere from 10 seconds to a minute in the UVC light to become disinfected. UVC-based air purifiers make you feel safer but based on the basic laws of physics they cannot work.

Contact-based germs

How is it even remotely possible that even the tiniest amount of fecal matter can enter my mouth? There’s a long list of microbes that are spread this way, including household names like E. coli, Listeria, and Salmonella. There are others that are not associated with food, such as E. faecalis, which inhabits perfectly healthy individuals’ gastrointestinal tracts and accidentally finds its way into the mouth of another.

Another notable example is Norovirus, which is widely associated with cruise ships as a major cause of diarrhea and projectile vomiting outbreaks – unfairly so since it is far more prevalent in nursing homes.

It doesn’t happen often but when it does it is brutal. A person, asymptomatic or sick, visits the bathroom and flushes the toilet leaving invisible droplets on the floor nearby. Later someone else visits the bathroom, placing their backpack or handbag on the floor for just a few seconds. Later, at their desk they put the bag on a table to get something out, and then has lunch, right there, at their desk. It couldn’t be healthier – a green salad and an apple. The table ‘looks’ clean, so the brain tells us everything is safe.

The salad greens could have been contaminated from the field. Even during processing and packaging you can’t be assured of 100% pathogen elimination. Then, of course, someone on the production line or in the kitchen may have not washed their hands well enough, or the leaves touched a surface that was contaminated by something else. Then there’s the apple. Like the salad it’s what they call RTE – Ready To Eat. It can’t be cooked so there is no way to kill any germs that way. Instead, it picks up the germs from the table and I take a big bite.

How many germs to I need to consume to fall sick? It depends on the species. For Norovirus you only need 10 virus particles, 100 bacteria for E. coli, a few hundred for RSV, 1,000 for Salmonella, 100,000 for Listeria. For perspective 1,000,000,000 bacteria weigh the same as a grain of salt.

Open Wounds and Vulnerability

The other entry point is an open wound, which is why antiseptics and antibiotic creams are so effective. Open wounds, even as minor as scratches and grazes are a prime reason why healthcare facilities and athletic locker rooms both have such high incidences of disease transmission. The other reason is that patients needing treatment are often already vulnerable – they may have weaker immune systems. Ironically, even the fittest athletes can suffer weakened immune systems following the stress from competing or over-training.

Disinfecting Rooms, Atmospheres, and Surfaces

In our post-covid world, or if not ‘post’ then with-covid world, we are coming together again – sharing spaces like we did before. But the notion of staying safe from a disease perspective has changed. While we may not wear masks, we might be more inclined to stay home to ride out an illness rather than be a trooper and go to work. In these shared spaces, EPIC iO AURA is a device that transforms the air in the room to a disinfecting atmosphere, safely sanitizing everything it touches – in the air on surfaces. It disinfects every square inch, of every room, every day. To learn more please visit https://epicio.com/biosecurity.