Masks don't work.

AAPS | Association of American Physicians and Surgeons

curated by Marilyn M. Singleton, M.D., J.D.

Transmission of SARS-CoV-2

Note: A COVID-19 (SARS-CoV-2) particle is 0.125 micrometers (μm); influenza virus size is 0.08 – 0.12 μm; a human hair is about 150 μm.

*1 nm = 0.001 micron; 1000 nm = 1 micron; Micrometer (μm) is the preferred name for micron (an older term)

1 meter is = 1,000,000,000 nm or 1,000,000 microns

Droplets

Virus is transmitted through respiratory droplets produced when an infected person coughs, sneezes or talks. Larger respiratory droplets (>5 μm) remain in the air for only a short time and travel only short distances, generally <1 meter. They fall to the ground quickly. https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(20)30245-9/fulltext This idea guides the CDC’s advice to maintain at least a 6-foot distance. Virus-laden small (<5 μm) aerosolized droplets can remain in the air for at least 3 hours and travel long distances. https://www.nejm.org/doi/pdf/10.1056/NEJMc2004973?articleTools=true Air currents

In air conditioned environment these large droplets may travel farther. However, ventilation — even the opening of an entrance door and a small window can dilute the number of small droplets to one half after 30 seconds. (This study looked at droplets from uninfected persons). This is clinically relevant because poorly ventilated and populated spaces, like public transport and nursing homes, have high SARS-CoV-2 disease transmission despite physical distancing. https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(20)30245-9/fulltext Objects and surfaces

Person to person touching The CDC’s most recent statement regarding contracting COVID-19 from touching surfaces: “Based on data from lab studies on Covid-19 and what we know about similar respiratory diseases, it may be possible that a person can get Covid-19 by touching a surface or object that has the virus on it and then touching their own mouth, nose or possibly their eyes,” the agency wrote. “But this isn’t thought to be the main way the virus spreads. https://www.cdc.gov/media/releases/2020/s0522-cdc-updates-covid-transmission.html. Chinese study with data taken from swabs on surfaces around the hospital https://wwwnc.cdc.gov/eid/article/26/7/20-0885_article?deliveryName=USCDC_333-DM25707 The surfaces where tested with the PCR (polymerase chain reaction) test, which greatly amplifies the viral genetic material if it is present. That material is detectable when a person is actively infected. This is thought to be the most reliable test. Computer mouse (ICU 6/8, 75%; General ward (GW) 1/5, 20%) Trash cans (ICU 3/5, 60%; GW 0/8) Sickbed handrails (ICU 6/14, 42.9%; GW 0/12) Doorknobs (GW 1/12, 8.3%) 81.3% of the miscellaneous personal items were positive: Exercise equipment Medical equipment (spirometer, pulse oximeter, nasal cannula) PC and iPads Reading glasses Cellular phones (83.3% positive for viral RNA) Remote controls for in-room TVs (64.7% percent positive) Toilets (81.0% positive) Room surfaces (80.4% of all sampled) Bedside tables and bed rails (75.0%) Window ledges (81.8%) Plastic: up to 2-3 days Stainless Steel: up to 2-3 days Cardboard: up to 1 day Copper: up to 4 hours Floor – gravity causes droplets to fall to the floor. Half of ICU workers all had virus on the bottoms of their shoes Filter Efficiency and Fit

*Data from a University of Illinois at Chicago review

https://www.cidrap.umn.edu/news-perspective/2020/04/commentary-masks-all-covid-19-not-based-sound-data

HEPA (high efficiency particulate air) filters – 99.97 – 100% efficient. HEPA filters are tested with particles that are 0.125 μm. Masks and respirators work by collecting particles through several physical mechanisms, including diffusion (small particles) and interception and impaction (large particles) N95 filtering facepiece respirators (FFRs) are constructed from electret (a dielectric material that has a quasi-permanent electric charge. An electret generates internal and external electric fields so the filter material has electrostatic attraction for additional collection of all particle sizes. As flow increases, particles will be collected less efficiently. N95 – A properly fitted N95 will block 95% of tiny air particles down to 0.3 μm from reaching the wearer’s face. https://www.honeywell.com/en-us/newsroom/news/2020/03/n95-masks-explained. But even these have problems: many have exhalation valve for easier breathing and less moisture inside the mask. Surgical masks are designed to protect patients from a surgeon’s respiratory droplets, aren’t effective at blocking particles smaller than 100 μm. https://webcache.googleusercontent.com/search?q=cache:VLXWeZBll7YJ:https://multimedia.3m.com/mws/media/957730O/respirators-and-surgical-masks-contrast-technical-bulletin.pdf+&cd=13&hl=en&ct=clnk&gl=us Filter efficiency was measured across a wide range of small particle sizes (0.02 to 1 µm) at 33 and 99 L/min. N95 respirators had efficiencies greater than 95% (as expected). T-shirts had 10% efficiency, Scarves 10% to 20%, Cloth masks 10% to 30%, Sweatshirts 20% to 40%, and Towels 40%. All of the cloth masks and materials had near zero efficiency at 0.3 µm, a particle size that easily penetrates into the lungs. Another study evaluated 44 masks, respirators, and other materials with similar methods and small aerosols (0.08 and 0.22 µm). N95 FFR filter efficiency was greater than 95%. Medical masks – 55% efficiency General masks – 38% and Handkerchiefs – 2% (one layer) to 13% (four layers) efficiency. Conclusion: Wearing masks will not reduce SARS-CoV-2. N95 masks protect health care workers, but are not recommended for source control transmission. Surgical masks are better than cloth but not very efficient at preventing emissions from infected patients. Cloth masks will be ineffective at preventing SARS-CoV-2 transmission, whether worn as source control or as personal protective equipment (PPE). "Masks may confuse that message and give people a false sense of security. If masks had been the solution in Asia, shouldn’t they have stopped the pandemic before it spread elsewhere?”