We’ve Been Living in the World of Droplets Long Before COVID-19

The purpose of technology is to facilitate human intentions. But to what extent? Does it protect us, or does it create a virtual reality infused with panic and questionable choices? When most of our social interplay takes place somewhere between servers, do you ever miss personal human interaction?

Live, in-person conversations can be fulfilling and inspiring. It turns out that they can be pretty contagious, too.

You know the situation when during an invigorating eye-to-eye talk, a piece of spit comes out of your mouth, and unintentionally hits a member of your audience. It’s embarrassing, right? Well, as it happens, this chunk of liquid that you’ve just expectorated is a droplet, and a huge one in fact.

Most of the droplets are significantly smaller, though, and we’ve been spraying them around long before the big one struck the eye of our listener.

While blabbering about viruses, most of the people are entirely unaware of the fact that they’re emitting droplets around them, all the time.

Droplets in Human World

We’ve been living in a world of droplets since the beginning of time. They created life; they follow it around the globe, and yes, they help spread other life-forms, such as viruses.

Chemically, an organic droplet is a dispersion of various organ-based components in a solution of mouth-originated electrolytes. In other words, droplets are pieces of our saliva that accommodate multiple particles.

According to the theory of Evolution, the primordial soup — the chemical ancestor of all living things — was actually a conglomerate of droplets. Each one contained molecules that eventually reacted, thus creating complex structures. Later on, these structures fused and initiated essential biochemical cycles that in time gave birth to the first cellular organism. And the evolution went on, facilitated by numerous droplet interactions.

Every evolved organism emits droplets. This occurs naturally: as the body releases a drop of water, it is bound to take some organic debris with it. However, in humans, most droplets are released into the environment through our mouths.

Every time we talk or even breathe, we hawk out a distinctive amount of liquid from our lungs and mouth, also called respiratory droplets. Regardless of how gruesome it may seem, the population has been sharing these droplets long before we’ve been sharing internet content.

The problem is when they carry a potentially dangerous content, like a virus.

In times of epidemics, we are afraid of catching viruses from non-sanitized surfaces. The thing is that we should be more cautious about droplets that carry them.

Droplets are Vehicles

Let’s look at it as an ordinary situation: the hot-headed driver hits you, but it’s not him that does the damage — it’s the heavy machinery he is operating.

In the case of viral transmission, the virus is the driver, and the droplets are the ones that crash into us.

Infectives are not dispersed through the air like specks of dust. They are carried in respiratory droplets.

Viruses are minuscule chemical constructs of nucleic acid and protein, wrapped in a sugar container, and as such, they cannot fly around without being quickly dissolved by the environment. That’s why they need a vehicle to survive and spread.

Droplets are tiny pieces of liquid emitted through our mouths. They carry parts of us and, when we’re infected, there is a higher chance that they enclose this pathogen as well.

According to the studies, the size of a COVID-19 virion is approximately 0.05–0.2 μm, while the size of its droplet-based vehicle is 10–100 times larger.

The Types of Respiratory Droplets

Respiratory droplets usually include epithelial cells or fragments of immune-cells dissolved in the electrolyte-solution from our saliva. They can also contain traces of drugs that a person uses, and, yes, they offer safe refuge to infective agents from our lungs and oral mucosa.

The size of a droplet varies significantly. However, considering the transmission of infectious diseases, we have two major types.

The ones that are larger than 5 μm in diameter are commonly referred to as plain droplets. They are pretty heavy and cannot travel long distances, as they quickly dry out and usually disintegrate within a meter. When inhaled, they get trapped in the upper respiratory tract and cannot go deeper into the lungs. They can be harmful if swallowed, though.

Droplet nuclei are smaller than 5 μm in diameter and have the potential to penetrate the lungs. In some cases, droplet nuclei can saturate the air around a person and are carried away by the air current. By becoming airborne, they can travel longer distances. How far they will go depends on the humidity, airflow, and temperature.

What Exactly Is Droplet Transmission?

Everybody’s talking about droplet viral transmission these days. And it’s no wonder — COVID-19 has infected more than a million people worldwide for a little more than three months. If we count in that a single person creates thousands of droplets just by talking for five minutes, well, there’s a gazillion of them flying around all the time.

Droplets come out of our mouths by:

• Coughing
• Sneezing
• Breathing
• Talking

A single sneeze can produce as many as 40,000 droplets of average size between 0.5–12 5 μm. The expiration velocity of a sneeze goes up to 100 m/s. So, cover yourself when sneezing. Always!

Droplets larger than 100μm instantly dry out before falling to the ground. The others can reach up to 2m.

Although they don’t travel far, droplets can settle on surfaces and remain there up to several days, depending on their composition and the environmental conditions.

These adjacent droplets are the primary sources of infections. And we are not even aware that they are planted there. Sole hand contact with these surfaces can set on a contagious event.

Regardless of whether you’ve been in a grocery store or at your uncle’s family dinner, wash your hands. Thoroughly!

Yes, even flushing a toilet can aerosolize some of the fecally transmitted particles. Be careful when you share a bathroom!

A series of cough emits up to 3,000 droplet nuclei, similar as talking for five minutes. So, if a guy is coughing next to you, he’s probably creating thousands of droplet nuclei. Cover yourself!

Droplet transmission differs from the airborne transmission. Droplet nuclei (< 5µm) can saturate the air and travel further, driven by the wind or a pulled by draft. This saturation is more likely to happen in crowded environments, such as hospitals, where the air is constantly being settled by small nuclei.

Droplet nuclei can be directly inhaled, and they can also remain on the premises after the host has gone.

Which Infections Are Transmitted This Way?

Depending on the infecting agent, the transmission is more or less likely to occur. There are three types of infectives that can be transmitted this way:

• Obligate — The ones that transmit only through droplets, such as Tuberculosis.
• Preferential — The ones that can enter a person’s body in different ways but are dominantly droplet-obtained. These are chickenpox, mumps, measles, influenza (the flu), whooping cough, and rhinovirus (the common cold).
• Opportunistic — Only droplet-transmittable in certain circumstances

So far, COVID-19 is considered as a droplet-preferential infectious pathogen. However, there is new data being harvested and published every day.

A study published on the 4th of March, which was conducted in Singapore, attended to three patients who had confirmed novel Coronavirus infections and showed symptoms. The researchers sampled 26 surfaces of their isolation rooms every five days.

The study concluded that COVID-19 droplet nuclei do not live for long, but there was significant environmental contamination, such as in the toilet, and along different close-contact contact surfaces. Therefore, they have the potential of airborne and fecal transmission.

Do Masks Protect Us From Droplets?

The filtration potential of the most efficient N95 surgical masks lies between the range of0.05–0.5 μm. This means that they can restrain any droplet from entering the wearer’s mouth.

If in a crowd or a new environment during an ongoing epidemic— use a mask!

However, a wool- or cotton-sheet-based mask-wannabe will not stop a droplet nuclei from invading your mouth.

The problem with masks is that they do not hermetically cover our mouths (and they’re not supposed to) and that most people take them off more frequently than they should.

Wrapping Up

The droplets cannot be seen. But it’s useful to think about this transmission and act on it!

In times of fast-spreading epidemics, there is no way of knowing whether someone polluted the surfaces around us with their own droplets. And controlling the crowd is not that simple, especially when in a supermarket frenzy.

It’s not likely that anyone would scrub off every pound of cheese they bring home with a hand sanitizer.

That’s why we stay home — to avoid spreading droplets around,and picking up someone else’s. The truth is that, in a non-infective scenario, we would be glad to do it, unknowingly.

Now, back to those human interactions.

Personal conversations indeed carry the greatest joy when it comes to talking to people. But in times of pandemics, the servers and smartphones will do the trick. Droplet transmission doesn’t apply to the electromagnetic field, anyway.