An era of Reusable N-95 masks.........................Really???

Re-Usable N-95 Masks..... 

Is it true????

(Click here for the Bengali version)

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The crisis of COVID-19 has stirred every aspect of medical science as it is growing and getting more infectious.

As the Pandemic is growing the demand for safety kits are growing exponentially. Instead of proper guidelines from the authorities; companies have failed to produce the efficient, approved products as it is required for COVID-19 situation.

This deficit in demand and supply has showed some different approaches to maintain the service uninterrupted. 

NIOSH and OSHA have permitted to use "Approved Particulate Filtering Facepiece Respirators" that at least can block 95% of airborne particles 0.3 um in size, manufactured by other companies. This effectively has reduced the crisis call in the medical services. But, somehow this approach is also failing as the crisis is developing day to day. 

Here comes the new solution to manage the supply disruption. They have leveraged the extended use and reuse protocols now.

Extended use protocol is, the N-95 respirators that have crossed its shelf life can be used, only if the efficiency remains same. 

Reuse protocols are not authorized by the manufacturers and yet under observation, but are gaining its application in the practical fields. Chinese and American engineers are devising new procedures for decontaminating and reusing the respirators. 

Decontamination???? How to kill a virus?

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Michael Mina, Asst. professor of epidemiology at Harvard University said, it is not very hard to kill a virus as long as it is not in a human body. "The simplest way is to take a mask and let it sit out for two weeks."

T.H Chan also mentioned something similar about killing a virus. "We all know the virus tends to die out after ten days or so."

But, this solution is not a practical approach regarding the present situation.

What are the ways to kill a virus???

Five simplest ways to kill a virus are,

1) Irradiation

2) Fumigation

3) Hot water

4) Steam

5) Baking

Each of them has shown effective results but they are not fulfilling the criteria for a successful decontamination.

A successful decontamination procedure must ensure that the masks come out as good as new. 

3M, the largest manufacturer of N-95 respirators, has given four criteria to satisfy proper decontamination procedure.

1> It should be effective against the target organism, like SARS CoV2

2> It should not damage the respirators filtration efficacy.

3> It should not affect the proper fit of a respirator

4> Be safe for the person using it.

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Ultra-Violet ray decontamination:

University of Nebraska University of Medical sciences showed that 15 mins of UV-C radiation to the exposed masks are enough to kill the virus.

They have used two UV-C towers containing eight bulbs in a completely isolated room, walls coated with special reflective paints. 

Fumigation decontamination:

Duke University Hospitals are using a testing device that can gradually build up 300-750 ppm of vaporized hydrogen peroxide inside a completely isolated room for decontamination. It has showed 20 mins exposure to vaporized hydrogen peroxide has successfully sterilized the masks without changing its efficiency.

The drawback is the procedure time. It takes 4 hours for de-gassing the room and to use the masks again safely.

These facilities are not possible in a dental clinic. May be in some clinics but for all, this is not an affordable one. So here comes the affordable yet not approved decontamination procedures

Hot water heating or steam

During February'2020, Beijing University of Chemical Technology has shown an effective way for decontamination by their specific "regeneration treatment" procedure of disposable masks.

It is a 3 step procedure for decontamination.

> Immerse the mask in 56⁰ C hot water for 30 minutes

The temperature and timing is crucial for this procedure.

> The masks are then dried with standard, non-static hair dryer for 10 mins

This step is crucial for restoring the filtering function by regenerating the electrostatic charge.

> To verify the regeneration of electrostatic charge small scrapes of paper is used. The papers will stick to the mask surface.

This method is effective for maintaining the filtering function of the masks only for one decontamination cycle. From the second cycle the filtering efficacy reduces.

This method is only applicable for house hold users and for those who are at low risk for infection. 

Using this method for medical professionals is not recommended.

In March' 2020, a team from National Health commission of China has shown the effective use of autoclave to decontaminate the exposed masks. The research is yet under process and one of the team members said, "It is well accepted that 30 min of pressurized steam at 121⁰ C can kill almost all pathogens."

He has also mentioned that the regenerated  masks can hold its efficacy up to 99% after the first cycle of decontamination. 

CDC has also shown its inclination about this method for decontamination of exposed masks.

Baking or Dry heat:

A group of researchers from Stanford University have shown that Baking the contaminated masks at 

75-100⁰ C in a higher humidity for 30 mins can show good results as a decontamination procedure. Baking above 125⁰ C may change the polypropylene layer and make the mask ineffective. 

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Comparison

Methods	Process	Time	Efficacy	Cycles
UV-C	Decontamination under UVGI	15 mins	90%	<10 decontamination
Fumigation	300-750ppm HPV	20 mins	90%	20 decontamination
Boiling heat	56⁰ C water,	30 mins	80%	1-2 decontamination
Steam heat	Autoclaving at 121⁰ C,	30 mins	80%	1-2 decontamination
Baking	Heating in 75-100⁰ C	30 mins	80%	20 decontamination

 

Results:

UV-C irradiation has shown effective results but there are some reports against it. As the N-95 mask is a 3D structure, penetration of UV-C is under question. Some of the contaminant pathogens are found in the deeper layers of the respirator. Also this is not a very cost effective process for everyone.

HPV has shown some promising results. Though it is under observation but it has shown good results for decontamination procedure. No degradation of mask is reported even after 20 cycles. Only the elastic straps have shown some degradation due to the handling procedure.

Steam or Hot water is not recommended for the medical professionals as it brings down the filtering capacity of an N-95 mask from 95% to 80% just after one cycle. A respirator with 80% efficacy is not considered as an N-95.

Among all of these three procedures dry heat decontamination has shown the best results till date. One mask can be decontaminated for 30 cycles at least without the change of efficacy. But the handling procedure, man made errors can cause damage to the filter layers of polypropylene and the elastic bands.

29th March, 2020; FDA approved the HPV procedure of decontamination up to 20 cycles for a mask. If not contaminated with blood or other bodily fluids.

Though approved by FDA, the manufacturers are not recommending this procedures as a way out. According to their protocols till May, only 4-5 cycles of decontamination are used for a mask by HPV.

 

 3M manufacturers are totally disagreeing with the facts of Steaming, boiling or baking procedures as these procedures are causing severe damage to the filter layers. 

The Supply and Demand ratio

3M manufacturers used to produce 500 million N-95 masks per year. This crisis has increased the demand beyond the estimated levels. They have achieved producing 600 million N-95 masks by the end of April 2020. But in aspect of a demand market from 3.2 billion population it is pretty low to support the crisis. 

What are the risks associated with the reuse of an N-95 mask?

*  Discomfort. It will be hard to breath through.

*  Ill fitting or loss of proper fit

*  Loss of filtration effectiveness

*  Risk of infection spread.

Is there any alternatives for N-95??

There is a recommendation for partial use of N-95 alternatives or N-95 equivalent respirators. 

Like, FP2 (Europe), KPN95 (China), P2 (Australia). CDC has given a list for 'equivalent regulatory designations' as an alternative to N-95 masks.

Elastomeric full face N-95, N-100, self contained breathing apparatus are most effective alternatives. But it is costly and availability is limited.

Expired N-95 stocks are also recommended by the NIOSH to supplement the deficit. Respirators that may retain their filter performance beyond the labelled date of shelf life can be used if in a good shape.

Non certified N-95 masks. CDC has stated that, “as a last resort, it may be necessary for healthcare personnel to use masks that have never been evaluated or approved by NIOSH or homemade masks. Use of these unapproved masks may be considered for care of patients with COVID-19, tuberculosis, measles, and varicella. However, caution should be exercised when considering this option.”

The chosen alternatives should at least provide a tight fit and should be disposable or at least compatible with sterilization by autoclave.

When to discard and when to re use??

There is a strict guidance from NIOSH to all the health care professionals to discard their N-95 masks after these following events.

* Discard your N-95 respirator following use during aerosol generating procedures.

* Discard if the mask is contaminated with blood, nasal or respiratory secretions or any bodily fluids from the patients.

* Use a surgical mask or face shield to reduce the surface contamination of the N-95 respirator.

* Hang the used N-95 respirators in a designated storage area or put them in a container, such as paper bags, in between uses.

* Storage containers should be disposed or cleaned properly.

* Clean hands properly with soap and water before touching the mask for donning or to adjust the mask.

* Use clean gloves for doffing the respirators after using it.

*  Avoid touching the inside of the respirator.

* Before reusing a proper fit test must be checked.

The OSHA guidance for N-95 respirators

- Once worn in the presence of an infected patient the mask is considered as contaminated and should be discarded immediately after leaving the room with proper hand hygiene.

- Reuse of the respirators should be done under proper guidance and must be discarded if the device is damaged or soiled.

- Use of proper face shield or surgical masks over the respirators may reduce the chances of surface contamination.

- One should take enough care to check the proper fit before reusing a respirator.

Few studies and their results

> 48% of the respirators failed the fit test after re-donning. This may be due to the users improper handling.

> The study suggests that the respirator must be discarded if it is contaminated by the secretions of sneeze or cough.

> The respirator must be discarded after close contact with a confirmed COVID-19 infected patient cause the virus has demonstrated ability to persist and remain infectious for a long time on the mask.

> Implementation of UVGI has shown effective results but it should be done under consideration of the manufacturers guide and the materials type.

> Anti microbial wipes cannot clean or sterilize the N-95 mask.

Some equivalent or alternative safe products for surgical N-95 respirators

1) NIOSH - N95 - 42CFR84

2) FFP2 EN149-2001

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3) KN95 GB2626-2006

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4) P2 AS/NZ 1716/2012

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5) Korea 1st Class KOMEL-2017-64

6) Japan DS2 JMHLW 214-2018

Top 10 N-95 manufacturers in 2020

3M        -        Honeywell         -         Kimberly Clark Corp.

Ambu    -        BD                    -         Prestige Ameritech

Alpha Pro Tech        -         Louis M. Gerson Company

Teleflex        -            Moldex

Shanghai Dashend         -        Future trends

How to check a Proper N-95

1) Check the approval authority. An original mask must have a NIOSH logo

2) Check the model number and correlate with Google

3) Check for the TC-approval number

4) Check for the Lot number

  Presented by Dr. Arka Bhattacharya

 

 

Infromations from

ECRI Clinnical evidence assessment

FDA N-95 respirators and surgical masks

Strategies for optimizing supply of N-95 respirators

FDA, understanding the difference

PubMed

3M website and brochure 

Duke University data access

CDC.gov 

fumigation for dental clinic

Fumigation and Dentistry

There has been recent interests in the use of chemical fumigation in health care facilities because of concerns regarding the COVID pandemic. 

The panic from the infection has generated a demand in the market for different fumigation chemicals and required machines. 

Dental clinics are more prone to contain the aerosol generated from a COVID-19 infected patient. This news over night has bulged the market in a high demand, with authorized and unauthorized sources of supply, and potential buyers. 

It is evident that fumigation of a hospitals or clinics with high concentration of toxic chemicals can reduce microbial agents on the surfaces to control infections. But fumigation effect over "SARS CoV2" is yet under observation. 

Fumigation chemicals are much more toxic than anticipated at their minimum concentration. There has been incidents where fumigants have escaped causing illness and death to exposed workers and even the general public. Chemical fumigation in any health care facilities should be conducted only in the most controlled settings.

Fumigation procedure

Formaldehyde fumigation is the most accepted method of sterilization in a hospital or clinical set up. It is the most commonly used and cost effective than the other methods.

Formaldehyde vapor is an extremely effective biocidal agent. 

It acts as an alkaline agent, inactivating micro-organisms by reacting with carboxyl, amino, hydroxyl and sulphadryl groups of proteins and amino groups of neuclic acid bases. 

Fumigation is mostly effective at above the temperature of 20°C and in 65% humidity.

 

Site preparation protocols before fumigation

1) Thoroughly clean windows, doors, floor, walls, dental chair, working table, and all surfaces with soap and water. (Preferably detergents)

2) Seal off the area by closing all the exhaust panels, doors, windows and plumbing vents to avoid the leakage of fumes.

3)  Shut down all the electronic items, lights, Air conditioner etc.

4) Prepare the solution according to the room size in cubic feet.

Worker preparation

1) Adequate care must be taken by wearing cap, mask, foot cover, spectacle, coverall etc.

2) Fumigation chemicals are irritant to eyes and nose and it's also recognized as a potential carcinogen.

3) Isolate the area and post a notice to avoid the premises before starting the fumigation procedure.

4) Single person working is not adequate to maintain all the necessary precautions.

Fumigation

A) Electric boiler fumigation method. 

For a 1000 cubic feet room, 500ml of 40% Formaldehyde solution added in 1000ml of distilled water is used in an electric boiler. The power source must be outside the room to operate the boiler. 

After preparing the boiler leave the room, seal the area properly and switch on the boiler.

After 45minutes (depending upon the room size and efficiency of the chemical) switch off the boiler and let the room remain sealed.

B) Potassium permanganate method:

Here the heat is generated by an oxidizer chemical. Potassium permanganate which is an auto boiling agent reacts with the formalin and generate fumes of formaldehyde. 

For a 500ml formalin solution added in 1000ml of distilled water, 450gm of KMnO4 is required to fumigate 1000 cubic feet area.

After initiating the fumigation procedure leave the room for 12-18 hours before using. 

Neutralization 

1) Take out the boiler or fumigation pot out side the clinic and let the air ventilate. 

2) Formaldehyde fumes are neutralized with ammonia solutions.

3) Cotton balls soaked with 300ml of 10% ammonia solution (for 500ml of formalin solution) is dispersed on the floor at least 4hours before the sterility test

4) Formaldehyde gas reacts with the ammonia vapor and produces hexamine or 

hexa-methylene-tetra-amine which is a harmless compound.

5) Switch on the A/C or exhaust at leats 2hours before the sterility test. 

Maths behind the solution preparation

A dental clinic with Length 20feet, Width 15feet and Height 10feet is 

20x15x10= 3000 cubic feet (LxWxH)

The formula comes as follows 

(500ml formalin x 3000cubic feet)/1000cubic feet = 1500ml of formalin.

(1 / 2) x measured room volume = required formalin solution.

To nutralize 1500ml of formaldehyde in a 3000cubic feet room volume around 900ml of 10% ammonia solution is used. 

Required Guidelines.

1) A Log Book is mandatory to keep all the records of fumigation procedure. Such as date, time, total time of fumigation, total time of neutralization, details of the workers involved and the dates of sterility test visits.

2) A lay out plan of the clinic must be attached with the Log book.

3) There must be a separate dressing room for the doctors, assistants and a separate patient waiting area.

4) all sorts of plumbing, cleaning and electrical works must be completed before the fumigation starts.

5) all apparatus should be cleaned like suction machines, AC units, focus lights according to the manufacturer instructions

6) surroundings should be free of garbage, bushes, drainage wastes etc.

7) A warning notice should be handy to isolate the area prior to fumigation.

8) separate footwear should be kept inside the clinics working area. 

9) A separate dress should be kept for the working area.

10) Fumigation procedure should be done periodically depending upon the case load.

Is it worthy?

According to an article published back in 17th May 2020, stated that WHO is not recognizing the procedure of spraying disinfectants or fumigation that can help you from SARS CoV2. 

'Spraying or fumigation of outdoor spaces or health care facilities is not recommended to kill COVID-19 virus or other pathogens because disinfectants get inactive due to the dirt and other pollutants.'

It has also mentioned that "if disinfectants to be applied, it should be done with a clothe or wipe soaked with disinfectant solutions." to clean the surfaces. 

Formaldehyde allergy:

Inhalation of formaldehyde may lead to 

1) Burning sensation

2) Irritation of eyes, nose

3) Coughing

4) Wheezing

5) Tightness of throt

6) Runny Nose

7) Breathlessness. 

eventually it may lead to Pulmonary edema, pneumonia and ARDS.

Accidental exposure to Formalin.

accidental exposure of skin with formalin solution can lead to allergic reactions. Primary cares are to flush the area of exposure with clean cold water. 

If you have some how consumed formalin solution by mistake start taking lot of water and milk to dilute the solution and visit your near by hospital facility. 

Other safe alternatives to Formaldehyde.

Baccillocid

It is a formaldehyde free disinfectant cleaner with low concentration effectiveness. 

It is pocket friendly 

Good material compatibility

And excellent cleaning properties with virtually no residues

It has a good bactericidal, fungicidal and virucidal activity

Composition

1,6 Dihydroxy, 2-5 dioxahaxane 

Glutaraldehyde 

Benzalkonium chloride

Alkyl urea derivatives 

Spectrum of activity

All fungi including candida albicans

All gram positive bacteria

All gram negative bacteria

Mycobacteria

Bacterial spores

Viruses including HIV, HBV, HCV and others.

Mode of applications 

Mopping with Bacillocid special mop for 10-15minutes

Fumigation 2% Baccilocid 20ml solution with one litter of water.

Mode of action

Gluteraldehyde combines with chemically bound formaldehyde in hydrolisation with water and acts as same as formaldehyde.

Only 30% of formaldehyde is released 

Benzalkonium chloride and urea derivatives acts as surfectant. 

Advantages

No irritation

Compatible with any surface

Non corrosive

Prolonged residual effect 

Reduction in maintenance of your HEPA air purifier.

Prolonged clouser time for clinic is not required.

Virkon

Multiourpose disinfectant

Contents are

Oxone / potassium per-oxy-mono-sulphate

Sodium do-decyl-benzene-sulfonate, sulphamic acid and buffering agents

Typically used as surface cleaning agents 

Chlorine dioxide

HPV

Hydrogen Peroxide Vapors

Drawbacks:

One of the major difficulties in any infection control technique in a dental clinic is that the environmental surfaces will be constantly recontaminated. 

Thus CDC does not recommend fogging or fumigating in the routine patient care areas where isolation for longer period is not possible. There is also lack of evidence that once cleaned by chemical fogging will reduce the risk of nosocomial infection.

Fumigation is being considered as a method of sanitization because gas and vapors can permeate areas that are not reachable. 

The decision to use fumigation in a dental clinic must be carefully considered as a breach in containment can injure patients, visitors and staffs including the medical professionals. 

To avoid such errors it is best to evacuate the premises before fumigating the clinic.

Fumigation in a dental chamber should be limited to those instances where benefits clearly exceeds the risk of human exposure and other environmental damage. 

Before incorporating risky procedures simpler and safer approaches to disinfect the clinic must be considered.

Dr. Arka Bhattacharya

DantaBihanga 

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