Air Date: 4-10-2020|Episode 581
This week on IAQradio+ we are going to have an in depth discussion on appropriate PPE, disinfection and testing options for those dealing with Coronavirus projects. Tony Havics has put together a terrific meta analysis of respiratory protection information and has also been putting together information on these other topics. Tony is one of the most respected industrial hygiene pros in the industry and we look forward to an informative discussion on how pros should be handling these issues.
Mr. Havics is an Honors graduate from Georgia Institute of Technology with a Bachelor’s Degree in Mechanical Engineering and is a registered Professional Environmental Engineer (PE) with over 25 years of experience. He has provided front end investigation, development of plans & specifications, development of work plans, cost estimation, and oversight of numerous facilities for remediation, refurbishing, or decommissioning including a launch pad, dam gates, a baseball stadium, a tire factory with 59 buildings, a biologically contaminated L1011, a hospital, JP-6 fuel tanks, former mental institute, former military buildings, etc. In the field of microscopy, he has performed analysis for asbestos, contaminants in products, other minerals, fibers, fungi, engineering properties, and has testified in federal court as an expert microscopist. Andrew has also performed failure analysis and forensic testing on numerous building products such as roofs, windows, flooring, drywall, piping, etc.
Nuggets mined from today’s episode:
Tony’s guidance for Covid19 cleanup is rooted in radiation safety. A three faceted approach of: Time, Distance & Shielding. Limit exposure time, provide distance between worker and contaminant, and wear shielding personal protective equipment.
Sum of particle capture efficiency
- Interception- particle touches fiber and get caught
- Impaction- particle can’t follow around corner (akin to driving too fast around a corner and not being able to stay in lane)
- Diffusion- “Brownian motion or pedesis is the random motion of particles suspended in a fluid resulting from their collision with the fast-moving molecules in the fluid. This pattern of motion typically alternates random fluctuations in a particle’s position inside a fluid sub-domain with relocation to another sub-domain.” Wikipedia
It is a common MISCONCEPTION that HEPA filters do not capture particles smaller than 0.3 micrometers.
Because of diffusion and other capture characteristics HEPA filters are more efficient at capturing particles <0.3 micrometers.
Most penetrating particle size sets the filtration test standard.
Virus or Virion? “A complete virus particle, outside the host cell, is known as a virion. Virion consists of nucleic acid surrounded by a protein coat called capsid (together called nucleocapsid) and in case of enveloped virus, again covered by an envelope. … and can infect other specific host cells.” Quora.com
Virus particles range between 20-180 nm, Coronavirus 2 (SARS-CoV-2) is 80-90 nm in diameter.
“A plaque-forming unit (PFU) is a measure used in virology to describe the number of virus particles capable of forming plaques per unit volume. … The concept of plaque-forming units of virus is equivalent to the concept of colony-forming units of bacteria.” en.wikipedia.org There are 40-1000 particles per PFU.
Sneezing puts out more than 100 X more droplets than coughing. Sneeze droplets travel further than cough droplets. Maintaining 6 feet of distance between persons provides protection against infection.
Face piece seal on face is critical to protective mask protection and performance.
Medical masks must meet FDA criteria. Medical masks provide good splash protection and aren’t great on particles.
NIOSH has a well refined respirator and mask testing process. Efficiency is how well does it capture? NIOSH tests using: salt particles, and DOP (dioctyl phthalate).Other researchers have used polystyrene spheres, latex particles, and actual biological agents in addition to salt and DOP. During NIOSH tests static attraction is neutralized; as such NIOSH tested devices will work better in the field than in the test lab.
“N95 – Filters at least 95% of airborne particles at O.3 micrometers in diameter. N means it’s not resistant to oil. Surgical N95 – A NIOSH-approved N95 respirator that has also been cleared by the Food and Drug Administration (FDA) as a surgical mask. N99 – Filters at least 99% of airborne particles at 0.3 micrometers.” cdc.gov
N95 masks provide good protection against particles and not great protection against splashes.
Filtering Face Piece N95, assumption is that they are fitted properly.
Fit factor outside versus inside leakage.
Chinese KN95 mask are designed to fit Asian faces.
Tony doesn’t trust surgical masks for viral remediation and cleaning.
For cleaning a building with known Covid19 cases, Tony specifies an N95 face mask. N95 masks are more comfortable to wear, easier to talk through and can be discarded if splashed. He would prefer ½ face respirators be worn because they can incorporate carbon and chemical cartridges, added particle filters and are easily cleaned. Not everyone feels comfortable wearing ½ face respirators.
Face shields prevent direct aerosol blow and do a reasonable job of limiting exposure to plaque forming units.
Need to ensure that process doesn’t damage the mask and straps. Ethyl alcohol is known to damage the material.
Hydrogen peroxide vapor (Battelle https://www.battelle.org/inb/battelle-critical-care-decontamination-system-for-covid19) masks can be decontaminated up to 20 times. Duke University https://techcrunch.com/2020/03/27/duke-university-uses-vaporized-hydrogen-peroxide-to-clean-n95-face-masks-for-reuse/
Wet Heat Steam Vapor 30 minutes
Tony is experimenting with dilute Clorox solution and Alconox.
Surface cleanliness is an important requirement of disinfection. For example, Legionella sits inside of protozoa. Ethanol and Clorox are among the disinfectants tested on surrogates. 1-3-minute dwell time will provide 3 log reduction, from 1000 down to 1.
If you are killing bacteria you should be killing viruses. Spore forming bacteria such as Anthrax and C diff are the most resistant to antimicrobials and enveloped virus such as Covid19 are the most vulnerable.
Covid19 Cleanup Supervisory Procedure
- Visual inspection before cleaning.
- Visual inspection during cleaning
- Visual inspection after cleaning
- Use of tracer (UV or infrared) and ATP or Mycometer.
- [Option: It can be useful to use PCR surface swabbing for COVID-19 RNA for insurance claims to confirm the virus was present.]
Pete Consigli, Restoration Industry Global Watchdog
There seems to be more questions than good answers, but Pete’s biggest concern is about COVID-19 post cleaning/sanitizing verification methodologies.
Verification of cleaning process or sanitizing claims is what “customers” want to know from service companies.
A global crisis seems to bring out opportunistic marketers making claims where it’s hard to separate the black pepper from the fly poo!
How do cleaning contractors know what to believe and how can their selected “process” be explained to the customer that the job was done effectively?
Assume bacteria from human skin and other sources will be present. On testing for total bacteria. Surrogate use of MS2 phage. If you’ve cleaned bacteria properly there shouldn’t be any viral material.
Rule 1- Never trust contractors. Rule 2-Never Trust contractors, Rule 3- Refer to rule number
- Be sure you know how to don and use PPE. When you don’t use it correctly it doesn’t protect.
- Cleaning is more important than disinfecting.
Tony Havics links:
Thank you to Pete Consigli for assembling the eulogy and link to complete Bob Bonwell industry eulogy:
Z-Man signing off
Question: What is an N95 FFR?
Answer: An N95 FFR is a type of respirator which removes particles from the air that are breathed through it. These respirators filter out at least 95% of very small (0.3 micron) particles. N95 FFRs are capable of filtering out all types of particles, including bacteria and viruses. N means non-oil particles.
John Lapotaire—-Indoor Air Quality Solutions, Winter Springs, FL