Covid19 Risk Assessment and Mitigation

55 years ago
10 minutes

By Heather Michel

⟺

Introduction

The purpose of this document is to detail general risks and mitigation strategies during the Covid19 pandemic with added information for other airborne and fomite driven infections. The list of risks and mitigations found in this document is not exhaustive. Use your best judgment when assessing any risk not listed. If you feel that you need to do more in any situation, do it. Consideration of what others think of your precautions should not preclude you from doing what you think is right. As information becomes available these guidelines will change. This information is valid to the best of my knowledge at this time.

Terms

  • Aerosols / Airborne – Particles that stay in the air for hours or days and are therefore airborne. Mitigate aerosol/airborne risk by opening windows and running HEPA filters.
  • Droplet – Particles within liquid droplets, say from a sneeze, cough, yelling, singing, etc and fall from the air onto the floor very close to their source. This is the source of the 6 foot social distancing rules. In addition, droplets land on surfaces and can drive fomite transmission. Mitigate droplet risk by wearing a mask, washing hands, and using hand sanitizer.
  • Fomites – Surfaces. Viral or bacterial particles land on surfaces from hands, sneezes, coughing etc. You can transfer these particles to you by touching the surface and then touching your face. Sometimes the particles can enter your system though cuts too small to see. Mitigate fomite risk by washing hands, using hand sanitizer, wearing gloves, and placing a barrier between you and the surface.

Methods & Assumptions

“Anything you do before a pandemic hits will seem over the top. Anything you do when a pandemic hits will not be enough.” – unknown

Overview

Covid19

Covid19 is a neurotropic, cardiovascular disease that causes immune system dis-regulation and dysfunction. Covid19 does this by destroying your T cells and B cells thus harming your bodies ability to fight of infection from old and new pathogens. There is also evidence that this destruction of T cells may increase your risk for cancer as T cells routinely destroy rogue cells before they can develop into cancer.

Covid19 transmits through the air and can stay airborne (attached to micro-particles for at least 90 minutes.) Covid19 does not spread well through fomites (surfaces). There are, to the best of my knowledge, no confirmed cases of fomite transmission. That being said, always remember basic hygiene. Handwashing (30 seconds with soap and warm water) and not touching your face is essential hygiene at all times, regardless of what germs are going around. Vaccination protects yourself from serious disease and reduces your viral load. Reducing your viral load means that you may get less sick, those you infect may get less sick, you may have a 25-30% reduction in your chance of getting autoimmune disease or Long Covid, and your body will provide less opportunity for the virus to mutate. (A reduced viral load is significant because a higher viral load correlates with worse disease outcomes.) Wearing an N95 or KN95 mask reduces your chances of catching the virus and reduces the viral load that you inhale. A paper mask can reduce the chances of catching a virus by 10x. A well fitting N95 or KN95 mask can reduce the chances of catching a virus by 100x.

Colds, Flu’s, and RSV Oh My.

Wearing an N95 or KN95 mask and handwashing can prevent respiratory infections. Handwashing (30 seconds with soap and warm water) and not touching your face is essential hygiene at all times.

Evaluating Risk

It is important to evaluate your personal and familial risk when out and about. Consider yourself, your family, and those you have regular contact with (co-workers for example.) We are only as safe from disease as the most vulnerable among us.

NOTE: Viruses replicate when they get into a host. If you reduce the amount of hosts catching a disease or the severity of disease you therefore reduce the chance for replication and the development of further variants.

Risks

Covid19 / RSV

Pregnancy, older age, obesity, and chronic health issues put one at higher risk for the acute stages of a Covid-19 infection. Getting Covid-19 puts you at risk for Long Covid. Even asymptomatic Covid19 infections can lead to Long Covid. Long Covid can include dysautonomia, male sterility, CFS/ME, organ damage, brain damage, neurological issues, cardiovascular damage, and nervous system damage. The risk of long Covid at this time is considered 1 in 8 or 12%.

Covid19 causes immune system disinfection and dis-regulation. This then increases the risk of catching severe forms of the flu, RSV and opportunistic bacterial infections. If you have had Covid19 in the past you should consider yourself immune compromised.

Long Covid

The risk of Long covid is more likely equal to or higher than 1 in 5. Women have a higher risk of long covid then men. Kids are 30% more likely to have Long Covid symptoms 90 days after infection. The symptoms and damage are system wide.

Per https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9935239/ “A total of 38 studies were included in the meta-analysis. In total, 6556 of 14,850 cases were reported as asymptomatic. The overall estimate of the proportion of people who became infected with SARS-CoV-2 and remained asymptomatic throughout infection was 44.1% (6556/14,850, 95% CI: 43.3%–45.0%). The predicted asymptomatic proportion peaked in children (36.2%, 95% CI: 26.0%–46.5%) at 13.5 years, gradually decreased by age and was lowest at 90.5 years of age (8.1%, 95% CI: 3.4%–12.7%).”

In addition, the chance of long covid is reported as ‘per infection’ with the odds increasing with each additional infection. If the odds are 20% as 1 in 5 would indicate you can read your chance by looking at the 20% column in the image below and then going down to the appropriate number of infections.

The CDC assumptions of two to three infections per year per person could be devastating in the long term.

Alternative Risk Theory: Immunity Debt

The notion of immunity debt is not supported by medical evidence. You are only “immune” from Covid-19 for a few weeks after infection. Thus you can catch Covid-19 and then Covid-19 again a few weeks later. Catching Covid-19 does not impart any long-term immunity and damages T cells and causes damage to your immune system. It is not unreasonable to consider Covid19 as airborne AIDS.

Risk Mitigation

Testing

One should test before gathering with others. One should proceed to test every day of the gathering when possible. It is important to note that RAT tests were designed to detect symptomatic infections of Covid19 and are not ideal for screening those who are asymptomatic or have not yet developed symptoms.

Image that describes how to perform a RAT covid test.
Source: https://twitter.com/ccleighton

CO2 Monitors to Asses Risk*

When using a CO2 monitor to measure “rebreathed” air use these guidelines:

  • <500 is equivalent to good outside air. Masks not necessary if you can reliably maintain 6-10 feet of distance between you and others.
  • 500 – 800ppm – masks are most likely not necessary. Wear an N95 or KN95 mask if high risk, uncomfortable, around sick people, or if you cannot reliably maintain 6-10feet of distance between you and others.
  • 800 – 1000ppm – wear an N95 or KN95. Consider running a HEPA air filter or opening window to reduce/ensure a 0-800 ppm.
  • 1000 – 1400ppm – Wear an N95 or KN95 mask. If you do not have to be in this location, leave. If leaving is not an option, turn on HEPA Filters and/or open windows to bring CO2 ppm down below 800ppm.
  • 1400+ – Leave the space immediately. If not possible, wear an N95 or KN95 mask, open windows, and turn on HEPA filters to reduce risk.
  • 2000+ – Extremely high risk. Wear an N95 or KN95 mask or better (consider N99 or elastomeric mask. Leave the space immediately.

The following chart shows how much recently exhaled air you are breathing in related to the CO2 level of the space. A CO2 monitor does not measure how much Covid19 is in the room but does give you an idea of how much risk of infection the space may present.

Mathematical Note: If the CO2 in the space is 700ppm, 0.7% of the air is rebreathed. You can reduce the risk of that air containing a virus by 100 times by wearing an N95 or KN95. If that 0.7% of air was full of virus then 0.7 / 100 = 0.007% chance of inhaling virus.

Masking to Reduce Risk

Indoors

When indoors in a public space or in your home with guests, wear a mask to protect against any respiratory disease or disease that is contracted through the respiratory system. Note that Covid19 can stay in the air for one to two hours after an infectious person has left the area (without open windows or HEPA filters.)

Outdoors

When outdoors, wear a mask to protect against both diseases if you cannot generally maintain a 6 foot distance to other people.

KN95, N95, and Surgical Masks... oh my. KN95 and N95 masks provide excellent protection. Cloth and surgical masks do not provide adequate protection. Ventilation is very important. Open windows and use a HEPA filter to improve air quality and provide as much airflow as possible. See the Corsi-Rosenthal Box box instructions.

Eye Coverings to Reduce Risk

It is possible to catch Covid19 though the eyes. If you are spending a prolonged period of time in a closed or contagion rich environment (A plane for example.), consider wearing goggles.

Disinfecting Surfaces to Reduce Risk

When indoors or outdoors, wear gloves to protect against Monkeypox unless you have time to disinfect a surface down and wait the stipulated amount of time  Be aware of any surface you are putting in your mouth as a potential risk. Washing or sanitizing hands can protect against other respiratory pathogens.

Disinfecting high touch surfaces can help reduce the risk of pathogens. Consider Disinfecting high touch surfaces regularly in your home and in hotel rooms etc.

More Sources & Resources:


Disclaimer: I am not a physician or a practicing scientist. I have a BS degree in Environmental Sciences only. This article does not constitute medical advice. This article also does not necessarily represent the current opinion of the CDC or WHO.