Effective Strategies to Reduce Exposure to Viruses

In case you weren’t aware, there’s a virus going around right now. If you didn't know already, you must never leave your house, because EVERYONE is wearing masks nowadays. This article will explain the best methods by which you can reduce exposure for yourself and those around you. There simply isn’t any feasible way to completely protect yourself from exposure, and that’s why it’s important to use every method available to reduce your chances of becoming infected. This article focuses on masks and respirators.

Most (but not all) countries are currently requiring the use of face coverings in order to minimize the spread of SARS-CoV-2. We’ll look at recommendations from experts, unpack the research on which masks are most effective, and explain how to use masks properly.

In the case of the novel coronavirus, the CDC notes that simple face coverings or masks can reduce its spread. It is required that people wear a face covering or mask to cover their nose and mouth when in the community. This is one of many public health measures people are obligated to take to reduce the spread of viruses in addition to physical distancing, frequent handwashing, and other preventive actions.

The CDC requires healthcare workers to wear face masks when working with patients who have the flu or any other virus. The CDC also recommends patients who show signs of respiratory infections be given masks while they’re in healthcare settings, until they can be isolated. If you’re sick and need to be around others, properly wearing a mask can protect those around you from contracting the virus and developing an illness.

For many years, scientists weren’t sure whether wearing a mask was effective at preventing the spread of viruses. However, recent studies suggest they can help. One 2013 study looked at how masks could help people with the seasonal flu limit spreading it when they exhale droplets containing the virus. Overall, researchers found masks led to a median of 33% reduction in how many virus people sprayed into the air.

So what’s in a cough? At least 20,000 viruses is the best estimate that research can conclude currently, which may be sufficient to infect many people. Julian Tang, a consultant at Singapore’s National University Hospital’s Division of Microbiology, says that as many as 3,000 tiny droplets are produced in a standard cough.

Using previous research on influenza viral loads in nasal secretions, and assuming that each coughed airborne droplet measures between 1 to 5 micrometers in diameter, that adds up to many, many viruses in a single cough. A micrometer, or micron, is one millionth of a meter, or one thousandth of a millimeter. “Based on this research and assuming that approximately 3,000 droplets are produced per cough, this range of viruses produced ‘per cough’ is anywhere between 195 to 19,500,” Tang told Reuters.

It’s important to note that this estimate of 3000 droplets is only referring to droplets that are very small and will remain in the air for a period of time. “This (3,000) is approximately the number of droplets estimated to remain suspended in air for long periods after a cough, so-called droplet nuclei. Larger droplets carrying influenza viruses are definitely also produced during a cough, but these will fall to the ground eventually and will no longer be considered to be significant in the airborne transmission of a virus,” Dr. Tang said.

We all need to be aware that if a person is sick, the droplets in a single cough will contain dramatically more viral droplets, as many as two hundred million individual virus particles. The number varies dramatically and changes over the course of an infection as the immune system clears out the virus. Generally, a sick person is most infectious as soon as the first symptoms appear and less infectious as his or her immune system clears the virus. If you’re sick, STAY HOME!

Tang also said an infective dose of flu virus would depend on a variety of factors, such as the constitution of people breathing in these droplets and whether or not they had been vaccinated. “It is impossible to give an exact number for an infectious viral dose, and this number will even differ for the same individual throughout the year. Most probably for immune people, the infectious dose will be much higher than for non-immune people. Hence, the benefits of vaccination,” Tang said.

"Those previously vaccinated or naturally infected to the same or a similar virus can develop a rapid antibody response and clear the virus in the respiratory tract before the virus can take hold and cause disease. (But) even immune people may develop symptoms if the viral load exposure is sufficiently high,” he added.

To properly research the viral load output of coughs, scientists use elaborate setups that reveal how much saliva is expelled per cough and where the tiny droplets go. They asked people to cough into masks that are carefully weighed before and after the coughs. They illuminate the flows of coughs with powerful lasers and fancy photo techniques and use powerful computers to model this flow of thousands of tiny particles. They use heated manikins and cough machines in rooms filled with tiny droplets of olive oil or theatrical smoke to track how air moves, where breath goes, and how exposed we are to someone else's cough.

Sneezing is even worse than a cough. Coughing expels tiny viral droplets at approximately 50 miles an hour, while sneezing projects these same droplets with substantially more force. A sneeze starts at the back of the throat and produces significantly more droplets, at least 40,000, which burst out at speeds greater than 200 miles per hour. The vast majority of the droplets are less than 100 microns across, the width of a human hair. They (viruses) cannot be seen with the naked eye.

"What happens to these droplets depends on their size," said fluid dynamicist Bakhtier Farouk of Drexel University in Philadelphia. He is working on software that models how microscopic droplets move around a room.

“Most of the larger, heavier drops fall quickly to the floor under the influence of gravity. The smaller and lighter particles are less affected by gravity and can stay airborne indefinitely as they are caught up in and dispersed by the room's airflow. Movements in a room can cause the heavier droplets to become airborne again after they have fallen to the ground or another surface. Making a hospital bed can kick up viruses on the covers. Opening a door can dramatically alter the airflow in the room and pull up viruses on the floor. Even walking through a room can spread droplets in a person's wake.” says Farouk

It is important to note that surgical masks only prevent large droplets of bodily fluids that may contain viruses or other germs from escaping via the nose and mouth. They do also minimally protect against intake of splashes and sprays from other people, such as those from sneezes and coughs.

The most effective part of wearing a surgical mask is that when people do get sick, the body tries to deal with the infection by bringing up mucus to help clear it. Some of this mucus is swallowed, carrying the virus down to be destroyed by stomach acid. However, some mucus (and virus) in the throat will be expelled when we cough or sneeze, and this expels the mucus (and virus) out of the body, thus beginning the infectious process anew.

It’s important to know that a cloth face mask doesn’t offer the same level of protection as surgical face masks. However, when worn by the public at large, they can possibly help reduce the spread of viruses. This is because they might help prevent people without symptoms from transmitting viruses via their respiratory droplets. Infected people who have noticeable symptoms will not significantly reduce the spread of infection while wearing only a cloth mask.

Another important point to make is that you need to wear your mask properly. They should fit snugly against the face, covering both your nose and mouth with as few open spaces as possible. Also, use ties or ear loops to keep them secure against your face. When removing the cloth face mask, avoid touching your nose, mouth, and eyes. Also, face masks shouldn’t be used by children under 2 years old, people who have trouble breathing, and people who are unable to remove their own masks safely.

We also need to make the distinction between ‘masks’ vs ‘respirators’. A respirator is NOT a large oxygen tank with a plastic mouth covering designed to increase oxygen intake. It should be noted that surgical masks (the most common type of mask currently being used) are strictly designed to protect the environment from the wearer, whereas the respirators are designed to protect the wearer from the environment.

An N95, N99, P100 respirator (the highest for personal respiratory protection) will not always provide the expected protection level against small virions. Surgical masks will let a significant fraction of airborne viruses penetrate through their filters, providing very low protection against aerosolized infectious agents in the size range of 10 to 80 nm.

In conclusion, we can determine that masks and respirators may have a small impact on virus transmission and infection. However, masks alone will not be sufficient to prevent the transmission and infection of airborne illnesses. So, always remember to wash your hands regularly and keep all contact to a minimum, for the most effective results possible.

Everybody stay safe!

Sources:

https://drexel.edu/engineering/about/faculty-staff/F/farouk-bakhtier/

https://sg.linkedin.com/in/julian-tang-36590118

https://www.reuters.com/article/us-flu-cough-idUSTRE54B16F20090512

https://www.livescience.com/3686-gross-science-cough-sneeze.html

https://www.healthline.com/health/cold-flu/mask?c=604039377387#types-of-masks

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3591312/

https://pksafety.com/blog/respiratory-basics-n95-vs-p100/

https://pubmed.ncbi.nlm.nih.gov/16490606/