• Can the level of aerosol penetration found in commonly used masks contribute to asymptomatic individuals spreading the coronavirus to family members and others?

  • Does the use of permeable masks enable super-spreader events found among teenagers?

  • With the exception of N95s and N100s, would any other mask properly protect us from virus-carrying particles?

  • Would high efficacy masks and respirators protect us, regardless of which SARS-CoV-2 variants are present?

  • Could the widespread use of reusable, high-efficiency PPE facilitate the #CovidZero exit strategy and drive COVID-19 cases to #Go2Zero in less than seven weeks?

How would you prioritize your resources?

Suppose one or more entities are leaking, possibly toxic substances. What would be your immediate reaction to prioritize your resources in addressing the problem?

  1. Do you search for evidence if the substance is harmful?
  2. Do you check the airflow of the room?
  3. Do you trace how the substance spreads?
  4. Do you consider a stronger filtration system for your ventilation system?
  5. Do you start clinical research for immunotherapy?
  6. Do you probe for different treatments?
  7. What about sealing the leak as your priority?

Obviously, sealing the leak and stopping the toxic substances from spreading further would be the most reasonable first step.

Modes of transmission of virus causing COVID-19

Large droplets are sprayed into the air like tiny cannonballs and typically fall to the ground within seconds in a 2m/6ft radius. Airborne transmission through aerosols can occur over a large distance ranging from seconds to hours. Aerosols will linger in the air like smoke.

Coronavirus can be transmitted by physical contact, saliva droplets, and inhalation of aerosols that can linger in the air for hours, even if the infected person has left the room. This transmission can be direct or indirect, from large droplets or small aerosols, coming from an infected person who is coughing, sneezing, breathing or talking.

Aerosols with the virus enter the respiratory system through the nose and mouth. Virus particles are deposited along the respiratory pathway, and can reach the deeper tissues of the lungs. This is a significant mode of transmission for COVID-19.

How many units of airborne infection (quanta) per hour are released from one person in different settings?

Resting – Oral breathing
Standing – Oral breathing
Light exercise – Oral breathing
Heavy exercise – Oral breathing
Resting – Speaking
Standing – Speaking
Light exercise – Speaking
Heavy exercise – Speaking
Resting – Loudly speaking
Standing – Loudly speaking
Light exercise – Loudly speaking
Heavy exercise – Loudly speaking
“An ounce of prevention is worth a pound of cure.”
― Benjamin Franklin

Effectively Cut The Transmission Routes

Viruses eventually degrade and cannot replicate so long as they are outside of the body. They also can’t mutate as long as they can’t replicate. The more effectively we block their transmission pathways, the sooner we can eliminate the disease. High efficiency masks and respirators have a low amount of aerosol penetration and can block those pathways.

umbrella with holes

Personal Protective Equipment

An umbrella is a type of personal equipment protecting us from water droplets.

Would you use an umbrella with holes in it? How much leaking would you accept?

How much does your mask leak?

0.3%, 5% or over 80%?

What is important

The virus that causes COVID-19 is about 0.12 microns in diameter. The aerosols that contain the virus are on average a few microns in size. Akin to colorless and odorless gases, they can travel over 7ft/21m and cover a greater area. Aerosols can stay in the air for many hours, even if the individuals have left the room.

By protecting ourselves effectively from aerosols, we are also safe from inhaling droplets; however, defending ourselves from large particles does not shield us properly from the aerosols.

Compared to high efficacy masks, the commonly used cloth face coverings allow a considerably large amount of droplets and aerosols to pass through.
In contrast to reusable respiratory masks, disposable single-use masks can decrease in efficiency with each use, making them more penetrable.
It is essential for the mask’s surroundings to seal properly. A poorly fit mask (e.g., due to gaps along the bridge of the nose, or gaps due to men’s beards) enables air particles to flow into the mask, as the mask is not in direct, tight contact with the skin.
The inside of the mask must stay uncontaminated at all times. One should regularly wash the outside and inside sections of a reusable mask. The outside layer continuously becomes contaminated as we use the mask. If not done properly, the inner layer may become contaminated, especially during the mask’s removal and storage. An example of poor storage is placing the mask in the same bag repeatedly, with the outside layer of the mask contaminating the bag.

Viral load vs Covid-19 severity and mortality

The intake dosage of many substances can determine the level of its effects. While there is no firm conclusion, research suggests, the amount of the virus a person takes in – the viral dose or viral inoculum – can affect whether they get sick and how sick.

How many virus particles have you inhaled in the last minute?

300, 50’000, or over 750’000 viruses?

Proper PPE matters

Based on a theoretical example, we could see how many viruses a mask wearing person could possibly inhale at one million particles in a confined environment in the same period.

The efficiency at filtering large droplets differ, but here the numbers for efficiency of small aerosols in range of 0.3 and 0.5 microns:

N100 (no gap)
KN99 (no gap)
N95 (no gap)
N95 (with gap)
KN95 (no gap)
Surgical masks (no gap)
Surgical masks (with gap)
Hybrid (….)
Hybrid (…)
Hybrid (…)
Bandana Face Mask
Pre-Shaped Face Mask (with gap)

N95 and N100 only

According to droplet flow visualization experiments, no face coverings, except N95 masks, would offer complete protection for someone exposed to virus-carrying particles within 6 feet. While no virus-carrying particles were observed to leak through N95 masks, enough particles to expose wearers to an infectious dose were found to leak through other face coverings, such as surgical and double-layer cloth masks.

It’s PPE and CPE

Masks and respirators protect us at a personal level, otherwise they would be called Community Protective Equipment. Fortunately, when we minimize risk on an individual level, we also reduce risk in the community by reducing an infection’s spread. This collective risk reduction will occur in a non-linear manner.

Collective Risk

Theoretically, if two people have 50% risk reduction each by wearing their masks, their collective risk is reduced by 75%. As more people wear masks, the effect compounds.

PPE Selection

Knowing what types of PPE you need to wear, and when, can make lifesaving differences. Click here to find a quick guide on the best types of PPE for you.


PPE Usage

Knowing how to properly use a reusable respirator is just as important as owning one. Click here for advice on how to put on, remove and store your reusable respirator.


PPE Decontamination

Wondering how to efficiently clean your respirators? Click here to find memorable tips to ensure you are always handling and wearing a clean respirator.



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