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Biosafety Hoods

Critical PPE Problems and Solutions

Coronavirus Prevention

For Covid-19 prevention, CDC guidelines should be followed. The following information is for reference only.

Nano-sized virus (0.05-0.12 micron) rarely floats in individual form. Even so, a few copies of an airborne virus are unlikely to trigger infection. It requires tens of copies of a virus swamp a spot on a cell to enable its penetrating the membrane and initiating infection. Airborne transmission of Ebola from an infected passenger in air travel didn’t happen. The facts seem to indicate that the long-distance air transmission rarely carries a critical mass capable of triggering an infection.

In fact, the most common threat from many communicable diseases is micron to mm-sized droplets (expelled from talking, coughing and sneezing) that often carry millions of virus and bacteria. These airborne droplets in short-distance air transmission can be filtered by high quality surgical masks. However, these infectious substances can fall on the hair and skin as well as environmental surfaces, and contact transmission occurs when people touch such contaminants or other contaminated surfaces and subsequently touch their nose or mouth.

Therefore, the best practice for disease prevention in infection-risk situations is to keep the head, face, and neck fully covered all the time.

The benefit of our hoods is to provide an isolation layer next to the skin for blocking micron-sized particles while comfortably allowing extended wear for continuous protection.

 

 VitaFlex's BioSafety Hoods

Useful for frontline healthcare workers and janitors in handling bio-hazardous substances or contaminated materials 

The innovative advantage is “COMFORT”

Soft form-fit to securely cover the entire head, face and neck without restricting head movement and wearer’s mobility. 

Easy breathability to keep the head cool for extended wear.

 

Airborne particles (without high pressure force) cannot penetrate the structures of our Biosafety hoods. Meanwhile, the ultrafine gaps between fibers allow body heat and perspiration to escape which keeps the head cool. Workers can comfortably wear our hoods all day for continuous protection.The design of our full-cover hood forms an air-pocket around the nose and mouth to serve as a facemask. The dense, 12 layer, fiber-composite structures were engineered to filter 95% of bacteria (ASTM F2101) and 95% of 1-micron particles (ASTM F2299). The efficiency of filtering submicron particulates is even higher (>99% for 0.1 micron) because submicron particulates are mostly attracted by static and attach more tightly to the surface of fibers.

The structures of our Biosafety hoods are qualified as level 1 liquid barrier (ASTM F1862) engineered to block body fluids or blood splashes, which is for protecting medical workers in conducting surgical operations such as intubation. To provide comfortable breathability for extended wear, the delta P was kept under 4 mm H2O/cm2. For reference, the delta P of high filtration surgical masks and disposable N95 masks is around 5 and above 20, respectively.

The suggested donning sequence is to put on our hood first, followed by goggles to protect the eyes. It is essential to select goggles that fit the wearer’s face curve for sealing around the wearer’s nose and allowing it to press firmly on the wearer’s nose bridge. Our hoods can be worn comfortably under a face mask or full-face respirator. In case the mask/respirator moves, our hood can provide an additional layer of barrier for continuous protection.

In extreme situations when PAPR (powered air purification respirator) is required, wearing a Biosafety hood under the PAPR or hazmat hood provides continuous protection after removal of the contaminated suit. Our Biosafety hoods should be the first PPE put on and the last removed.

Our hoods are well constructed and reusable. They can be conveniently sterilized by soaking in commercial bleach concentrate for 5 minutes followed by rinsing them in clean water and airdry or in dryer with low heat for 10 minutes. To ensure the durability our hoods, we have tested washing them in industrial washing machine over 15 cycles of 30 minutes with warm water and tumble dry at low heat (130F) for 10 minutes.

Worn in conjunction with conventional protective equipment, our hoods solve many of their shortcomings. Find details in the brochure attached on the left panel.

 

My Continuous Efforts in Coronavirus Infection Prevention

The Creation of Biosafety Soft-stretch Hoods

Dr. De-Sheng Tsai

I learned nonwoven manufacturing twenty-five years ago. I started by co-managing two polypropylene spunbonded nonwoven lines. My graduate study was not in fiber engineering; rather in plant physiology with intensive work on protein purification and some gene cloning and sequencing.To benefit my research, I took courses in biochemistry, molecular biology, and immunology. This academic training has enabled me to continue to follow and understand articles in medical journals, epidemics reports, and CDC posting. What I have learned has allowed me to develop effective protective apparel.

The lack of adequate equipment for primary head protection has been the problem in many daily jobs and in catastrophic events. My latex-free elastic nonwovens provide the breakthrough materials that gives a soft and stretchy structure excellent for making protective head coverings. Treating a piece of woven textile for multiple functionalities is difficult, if not impossible. However, by bonding individually treated elastic nonwoven fabrics into a multi-layer structure, apparel can be economically made with a combination of functionalities while maintaining softness and breathability.  I have applied this concept in manufacturing a series of soft-stretch hoods (Dust Hoods, Spray hoods, UV Hoods, and BioSafety Hoods).

In the summer of 2014, I was developing an early version of Biosafety hoods for crime scene cleanup without noticing the worsening Ebola situation in west Africa. That September, medical workers in the US contracted the Ebola virus while caring for an infected patient. Subsequently, more than 3,000 purchase orders were received in a three-week period. With limited inventory, we had to prioritize our supply to VA hospitals and the military. Still, we sold out all our hoods before the end of October. In the following years, I enhanced our Biosafety hoods with functionality of blocking blood splashes. In late fall of last year, another advanced version with alcohol repellency was added. 

Many surgeons refuse to wear bouffant caps possibly because of their sloppy look which is more suitable for mixing salads in the cafeteria. Our hoods are becoming a favorite for medical workers because of their tight fit and neat, professional appearance. Upon wearing our soft-stretch hoods, the soft form-fit gives the wearer a sense of security from the feel of dependable protection. This was exactly intended as a part of our original design.  Our hoods are also replacing facemasks as a more complete protection in many work environments by covering the entire head, face and neck. There is only one elastic nonwovens process line (which was built by DuPont at VitaFlex’s plant in Burlington, North Carolina) and I am the scientist to continue developing elastic nonwovens and soft-stretch protective hoods.  However, before the completion of an expansion in 2021, the current capacity may only last for a few months in dealing this latest Covid-19 outbreak.  April 15 update:  While maintaining uninterrupted supply of our Biosafety hoods to several healthcare systems including military hospital overseas and VA medical centers, we have accomplished processing additional 1 million square yard material (elastic nonwoven composites) for continuously manufacturing Biosafety Hoods.

 

The Problems with Hooded Coveralls 

Unbearably hot and Restricted Wearer’s Head Movement and Mobility

The disposable coveralls have been popular in shielding against contaminants in workplaces.The classic design has an integrated hood to cover the back of the head and with its elastic edges cover the upper part of forehead. While working, the hood easily pulls away from the wearer’s head. If worn with a full-face respirator, duct tape has to be used to attach its edges to the face shield of the respirator. This worsens the problem of restricting head movement. Some new designs have a larger hood to enable wrapping around the wearer’s face for more protection. However, it severely restricts head movement and mobility. It is more difficult for the wearer to bend their neck or turn their head and quickly causes exhaustion. The heat and humidity build up quickly cause anxiety and dizziness. For reference, wearing hooded coveralls is prohibited when working in confined spaces or on high structures. The updated CDC guidance also recommends the use of coveralls without integrated hoods in epidemic outbreaks.

Workers’ bodies often come in contact with or are held tightly against work objects. To isolate contaminants in liquid or viscous forms, the disposable coveralls need to be made of Tyvek or membrane-laminated or coated nonwoven fabrics to create impermeability. These materials are not breathable and make the wearers hot. On the contrary, workers’ heads and faces rarely ever contact work objects; rather, the heads always stay at a higher position and at a distance. Since heads are more sensitive to heat and humidity, the materials used for making the hoods should be different from that of the body covering. It should have good breathability and need less liquid impermeability.  VitaFlex’s Latex-free Elastic Nonwoven Fabrics are the long-awaited breakthrough material that gives an elastic structure while maintaining the breathability and barrier functionality of nonwovens. This enables the making of protective hoods that are soft and stretchy to fit comfortably and securely on the wearer’s head.

The Solution: The practical solution is to wear our soft-stretch hoods with a high-collar coverall suit. Our hoods keep the head protected and cool. They also allow freedom of head movement and wearer mobility. To complete full coverage of the head, the donning sequence is to put on our hood first, followed by goggles to protect the eyes.

Why Use N-95 Masks?

Their high filtration is overkill for regular work; on the other hand, their poor fit makes them very undependable in urgent or extreme situations.

Worst of all, wearers cannot breathe through the mask

N95 masks have been overpromoted for their usefulness in blocking viruses. The particle filtration efficiency (PFE) of materials is defined by the percentage of a specific size of particle blocked when tested at a specific air flow. NIOSH certifiesthatN95 filters block 95% of 0.3 micron particles at a high air flow rate of 85 liters/min. Undoubtedly, N95 can be a good specification for HEPA filters that block particles in an air flow driven by a horsepower-rated motor. This specification is too heavy for a facemask without a pump since a human’s lung breathing power is only 8 liters/min.

In comparison, surgical masks are tested at an air flow of 28.3 liters/min to filter 95% of 1-micron particles. When tested near a normal breathing rate (5-10 liters/min) in my experiments, surgical masks, N95 masks, and some cloth masks all showed the same efficiency of filtering 100% of 1-micron particles.It is a big misconception that the excessive thickness of N95 always provide more protection against airborne particles. Otherwise, N100 should be even better.  The problem of excessive thickness is creating great breathing difficulty.

It is easy to manufacture N95 masks. Without a requirement for a limited air-flow resistance (delta P), the high filtration of N95 can be easily achieved simply by making the mask thick enough (with many low-cost materials). Based on delta P calculation, bonding five layers of surgical masks together can achieve the N95 filtration.

Nano-sized virus (0.05-0.12 micron) rarely floats in individual form. Further, sub-micron particulates are charged and mostly aggregated into micron-size granules. Therefore, the efficiency of filtering submicron particulates is often higher than filtering micron particles because submicron particulates are attracted by static and attach more tightly to the surface of a filter’s fibers.

Respirable particles of 1 to 15 µm are generally considered industrial health concerns and they can be blocked by cloths and nonwoven fabrics that make facemasks. However, the problem with face masks (cloth, surgical, and N95) is leakage. The elastic ear-loops of flat facemasks are either too loose or too tight for proper fit. The doom-shaped don’t fit well because faces vary in shape and nose-bridge height. Their elastic straps have to be uncomfortably tight to fit at all. Even then, the mask moves and leaks when the wearer talks or sweats.

Many disposable N95 masks are problematic. Mainly, they do not fit well on many people. Although fit testing is required, people cannot always remember which models/makes of N95 mask fit them best and companies cannot stock all models to meet the demands of all employees.Their poor fit makes them very undependable in lethal environments. Why would anyone risk their life that the two simple elastic straps of a N95 mask can maintain a reliable seal in a lethal environment? Further, people simply cannot trust their two elastic straps to maintain a reliable seal in a lethal environment. The fit testing cannot always guarantee against leakage when the wearer is working since the mask can move while speaking or sweating.Most importantly, what has been missing in the N95 fit testing is the duration of wear which needs to be at least 60 minutes.This would allow 20 to 30 minutes of actual work when considering time needed for donning and safely doffing protective gear.

High filtration means nothing if the mask cannot be worn comfortably for extended periods of time. Users often remove the mask or place it on their forehead while working because of breathing discomfort and feeling anxious from insufficient air. This leaves them un-protected. In SARS outbreak, many doctors and nurses contracted the virus even when wearing a N95 mask. Some reports have pointed out that because the mask was so difficult to breathe through that most of them did not keep the N95 masks on all the time. Some might have unconsciously pulled the masks away for seconds while performing intubation procedures on infected patients.

About Wearing Mask

Although masks may not be fully functional in protecting the wearer because of leakage, their containing spittle serves the great purpose of limiting spray of infectious substances in addition to providing an isolation layer covering the nose and mouth. Wearing facemasks is clearly a low cost and effective way for infection prevention.

On the other hand, for workers, our soft-stretch hoods provide a more complete protection bycovering the entire head, face, and neck. They can replace facemasks in many environments and can be worn in conjunction with a mask or respirator.

 

Did your safety instructor tell you a N95 is all you need?  

Could it be possible that something better, more appropriate, more advanced, and even more affordable is available?