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  • Theresa Sauter

Cloth Masks Do Nothing To Stop The Spread of COVID -Listen to the experts in Industrial Hygiene.

Are our doctors, scientists, or public health officials “experts” in personal protective equipment (P.P.E.) masks? Many mistakenly think that they are. Read on, and I think what you are about to learn may surprise you. Stephen E. Petty is an expert in the field of Industrial Hygiene. You may ask, what is an Industrial Hygienist? Industrial Hygiene is the science and art devoted to the anticipation, recognition, evaluation, and control of those environmental factors or stressors, including viruses, arising in or from the workplace, which may cause sickness, impaired health and wellbeing, or significant discomfort among workers or the citizens of the community.

Industrial Hygiene is fundamentally concerned with the proper methods of mitigating airborne/dermal hazards and pathogens and the design and use of engineering controls, administrative controls, and personal protective equipment (P.P.E.), among other things.

Medical doctors, virologists, immunologists, and many public health professionals ARE NOT qualified experts in these areas under the credentials mentioned above.

Mr. Petty has an impressive resume. He has testified about the futility and danger caused by an individual wearing a mask to avoid transmitting or becoming infected with Covid-19. Mr. Petty holds relevant industry certifications, including board certifications as a C.I.H. (Certified Industrial Hygienist), a C.S.P. (Certified Safety Professional), and as a P.E. (Professional Engineer) in six states (Florida, Kentucky, Ohio, Pennsylvania, Texas, and West Virginia).

Mr. Petty has also served as an expert in personal protective equipment and related disciplines in approximately 400 legal cases. He has often been certified as and provided testimony as an expert in these areas. He is currently serving as an expert in the Monsanto Roundup and 3-M PFAS litigation.

On May 7, 2021, the Centers for Disease Control (C.D.C.) updated its guidance, providing that the primary mechanism for transmission of Covid-19 is through airborne aerosols and not, as previously stated, by touching contaminated surfaces or through large respiratory droplets, as also noted during previous periods of the pandemic.

Airborne viral aerosols can consist of a single viral particle or multiple viral particles clumped together and usually smaller than five µ (microns) in size. By comparison, droplets are >5 µ to >10 µ in size.

A square micron is approximately 1/4000th of the cross-section area of a human hair and 1/88th the diameter of a human hair.

Covid particles are —1/10 of a micron or —1/40,000th the area of a cross-section of a human hair or —1/1,000th the diameter of a human hair.


Particles smaller than 5µ are considered very small and very fine or aerosols. Microscopic particles do not fall by gravity at the same rate as larger particles and can stay suspended in still air for a long time, even days to weeks. Because they remain suspended in concentration in indoor air, microscopic particles can accumulate and become more concentrated over time indoors if the ventilation is poor. Tiny airborne aerosols pose a significant risk of exposure and infection because they easily reach deep into the lung since they are so small, which partly explains why Covid-19 is so quickly spread. Small amounts of microscopic SARS-CoV-2 Viral Particles can cause an infection in a host.

Exposure to airborne aerosols is a function of two primary parameters: concentration and time. To be "safe" from the SARS-CoV-2 Virus, we want to minimize exposure to viral particles and minimize the time of exposure. The cloth masks do not stop viral particles; the microscopic particles may sit on the interior and exterior of the mask, enhancing both the concentration and time of exposure. Viruses and bacteria thrive in moist, damp environments, like behind the wet mask of a child sitting in the same mask for six to eight hours a day at school.

For many reasons, personal protective equipment (P.P.E.) is the LEAST desirable way to protect people from tiny airborne aerosols. Moreover, masks are not P.P.E. since they cannot be sealed and do not meet the provisions of the Occupational Safety and Health Administration (OSHA) Respiratory Protection Standard (R.P.S.), namely 29 CFR 1910.134. Regarding P.P.E., facial coverings do not effectively protect individuals from exposure to tiny airborne aerosols, and a device referred to as a respirator is required to provide such protection.

The American International Health Alliance (AIHA), in their September 9, 2020 Guidance Document for COVID-19, noted that the acceptable relative risk reduction methods must be >90%; masks were shown to be only 10% and 5% and far below the required 90% level.

Similarly, Shah, et al, 2021, using ideally sealed masks and particles 1 micron in size, reported efficiencies for the more commonly used cloth masks and surgical masks of 10% and 12%, respectively.

Ordinary cloth mask can NOT be perfectly sealed; thus “real world” effectiveness would be even lower.

Industrial hygienists refer to a “Hierarchy of Controls.” They implement a Hierarchy of Controls to minimize exposures, including exposures to tiny airborne aerosols like Covid-19. Regarding practical or “engineering” controls, industrial hygienists focus on practices that dilute, destroy, or contain airborne hazards (or hazards in general).

P.P.E., especially facial coverings, do not dilute, destroy, or contain airborne hazard. Therefore, facial coverings do not appear anywhere in the Industrial Hygiene (I.H.) Hierarchy of Controls for tiny airborne aerosols like Covid-19. The respiratory system, however, is designed to eliminate airborne hazards through a variety of innate natural mechanisms, including but not limited to:

  1. Sneezing

  2. Coughing

  3. Exhaling

  4. Spitting

  5. Excretion through sweating, urinating, and by other organs of the urinary system.

(Masking the face interferes with natural elimination of toxins and other harmful waste products; making the person wearing a mask at a greater risk of keeping toxic substances in the body). Children should be encouraged to sneeze into a tissue, to exhale and to practice careful natural excretion but there are inherent risks associated with conditioning children not to fully exhale and to remain in masks for an undetermined amount of time.

Even respirators (part of the P.P.E. Category and NOT MASKS) are the last priority on the Hierarchy of Controls. Cloth and/or Paper Facial coverings are not comparable to respirators, and leakage of viral particles occurs around the edges of ordinary facial coverings. Thus, regular facial coverings do not provide a reliable level of protection against the inhalation of microscopic airborne particles and are not considered respiratory protection. (For example, during the seasonal forest fires in the summer of 2020, the C.D.C. issued general guidance warning that facial coverings do not protect against smoke inhalation. That is because facial coverings do not provide a reliable level of protection against the tiny particles of ash contained in smoke. Ash particles are substantially larger than Covid-19 aerosolized particles).

Ordinary facial coverings do not meet any of the several key OSHA Respiratory Protection Standards for respirators. Because of the gaps around the edges of facial coverings, they do not filter out Covid-19 aerosols.

The policy stating masks will be worn without gaps defies known science that masks worn today cannot be sealed and always have gaps. The effectiveness of a facial cloth covering falls to zero when there is a 3% or more open area in the edges around the sides of the facial covering.

Most over-the-counter disposable facial coverings have edge gaps of 10% or more. When children use adult-sized facial coverings, edge gaps will usually significantly exceed 10%. Even short breaks (e.g., to eat) expose individuals to Covid-19 aerosols in indoor spaces. Ordinary cloth facial coverings do not provide any filtering benefit relative to particles smaller than 5µ if not sealed.

Substantial mitigation of Covid-19 particles could be immediately achieved by:

  1. opening windows and using fans to draw outdoor air into indoor spaces (diluting the concentration of aerosols)

  2. setting fresh air dampers to the maximum opening on HVAC systems

  3. overriding HVAC energy controls

  4. increasing the number of times indoor air is recycled,

  5. installing needlepoint ionization technology to HVAC intake fans

  6. installing inexpensive ultraviolet germicide devices into HVAC systems.

All of the above-referenced techniques are more effective and meet the standard industrial hygiene hierarchy of controls (practices) for controlling exposures in place for nearly 100 years.

The use of cloth facial coverings does not fit within these essential controls since masks are not P.P.E. and do not provide an adequate s