WFI Mask Webinar Dealt with Key Issues

More Rapid Air Changes Spread the Virus

U.S. Needs to Provide Aid to India

ASHRAE Provides Guidance for Protecting Voters

Chinese Researchers Create Charged Nanofiber Media with Silver for Anti-Microbial  Function

Filti Supplies MERV 16 Air Filters Using Nanofiber Technology

Gyms Need Better Air Filtration Generally

Large French Retailer Installs Camfil HEPA Filters

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WFI Mask Webinar Dealt with Key Issues

On Tuesday WFI held an on line webinar relative to masks. Christine Sun stated that “the webinar included three experts in the field for the latest update on the facemask market, technologies and testing used to certify the masks used. Ms. Janelle Bentz, Nelson Labs, provided updates on testing methods, Dr. Peter Tsai, University of Tennessee, provided knowledge on the meltblowing and electrostatic charging technologies, while Mr. Bob McIlvaine, McIlvaine Company, provided updated information on the facemask market.

In addition to the presentation, we also had experts discussing and reviewing important topics in the Q&A session. There was significant discussion around the testing of masks and where the market is heading, plus questions about the manufacture of meltblown materials for masks.”

Wendover Brown of Vogmask asked the question as to whether nanofibers were efficient enough to meet the N95 efficiency requirements. Dr Tsai answered a slightly different question as to whether the nanofiber media would capture the virus.

His answer was an explanation that the pore size in the nanofiber media is considerably larger than the virus. Pore size in turn is a function of packing density which in turn determines pressure drop.

The implication was that only the charged meltblown media had the ability to capture the virus at acceptable pressure drop in a face mask. 

This view is counter to that of some of the media suppliers. They point out that measurement is made at 0.3 microns because this is the most difficult particle diameter in terms of capture.  Smaller particles are subject to Brownian movement and are easier to capture.

In addition the argument is that the virus particles are attached to either droplets or fomite which is larger in particle size. So we need further discussion of this subject.

Bob McIlvaine was asked to define high efficiency masks. He replied that the metric should be fitted filter efficiency (FFE). A combination of filter efficiency and leakage which would prevent inhalation of  90% of the 0.3 micron particles would have a 90% FFE. So the filter efficiency might only be 93% but if the leakage is 3 % or less then the mask is just as efficient as an N95 with 5% leakage.

Realistically this FFE of 90% efficiency should be considered very high. Probably the best that can be achieved on the average is 85% for a mask in actual use by the public. The reason is that the way the mask is worn is very important. Averaging less than 10% leakage can be challenging.

Pressure drop is a bigger problem with masks than with filters but the same principles apply. 

Here is what American Air Filter says about the subject.

Particles that are 0.5μm in size or smaller tend to follow increasingly erratic paths as particle size decreases, a phenomenon known as the diffusion effect. As such, HEPA and ULPA filters are often rated according to their most penetrating particle size, or the size of particles that most readily pass through them. As depicted in this line graph, filters that achieve the same efficiency rating, in this case ULPA filters rated at 99.999%, are not necessarily equal in their MPPS performance.

There is a need to evaluate risk along with fitted filter efficiency. Guidance should be on a relative rather than absolute basis. For example until COVID most visitors and  personnel in a hospital did not wear a mask. Masks were used by those involved with infectious or vulnerable patients.
 

In the future it is very likely that everyone entering a hospital including visitors will need to wear a mask to reduce hospital acquired infections (HAI). This does not mean that the visitor needs to have a mask with the same fitted filter efficiency as the nurse working with cancer patients.

The CDC is struggling with absolutes such as when to wear a mask outside and when to go without one. The fitted filter efficiency is just one more variable to be integrating. So there can not only be a choice of whether or not to wear a mask but what FFE level mask do you need? 

McIlvaine Company will be pursuing this subject with various people in the industry and welcomes input from the readers.  This would include additional questions for Dr Tsai and for Janelle Bentz who is an expert on the testing.

 

More Rapid Air Changes Spread the Virus

Vigorous and rapid air exchanges might not always be a good thing when it comes to addressing levels of coronavirus particles in a multiroom building, according to a new modeling study.

The study suggests that, in a multiroom building, rapid air exchanges can spread the virus rapidly from the source room into other rooms at high concentrations. Particle levels spike in adjacent rooms within 30 minutes and can remain elevated for up to approximately 90 minutes.

The findings, published online in final form April 15 in the journal Building and Environment, come from a team of researchers at the U.S. Department of Energy’s Pacific Northwest National Laboratory. The team includes building and HVAC experts as well as experts in aerosol particles and viral materials.

“Most studies have looked at particle levels in just one room, and for a one-room building, increased ventilation is always useful to reducing their concentration,” said Leonard Pease, lead author of the study. “But for a building with more than one room, air exchanges can pose a risk in the adjacent rooms by elevating virus concentrations more quickly than would otherwise occur.

“To understand what’s happening, consider how secondhand smoke is distributed throughout a building. Near the source, air exchange reduces the smoke near the person but can distribute the smoke at lower levels into nearby rooms,” Pease added. “The risk is not zero, for any respiratory disease.”

The team modeled the spread of particles similar to SARS-CoV-2, the virus that causes COVID-19, via air-handling systems. Scientists modeled what happens after a person has a five-minute coughing bout in one room of a three-room small office building, running simulations with particles of five microns.

Researchers looked at the effects of three factors: different levels of filtration, different rates of outdoor air incorporation into the building air supply, and different rates of ventilation or air changes per hour. For downstream rooms, they found an expected clear benefit from increasing outdoor air and improving filtration, but the effect of increased ventilation rate was less obvious.

Scientists studied the effects of adding varying amounts of outdoor air to the building air supply, from no outside air to 33 percent of the building’s air supply per hour. As expected, the incorporation of more clean outdoor air reduced transmission risk in the connected rooms. Replacement of one-third of a building’s air per hour with clean outdoor air reduced infection risk in downstream rooms by about 20 percent compared to the lower levels of outdoor air commonly included in buildings. The team noted that the model assumed that the outdoor air was clean and virus free.

“More outside air is clearly a good thing for transmission risk, as long as the air is free of virus,” said Pease.

When the infected person in the office to the left coughs, respiratory droplets containing viral particles exit via the office’s vent in the ceiling. Some droplets exit the building, while some are sent back into the building and into multiple rooms through the air-handling unit. A PNNL team found that a high ventilation rate can increase viral particle levels downstream of a source room. (Illustration/Animation: Cortland Johnson/Sara Levine, Pacific Northwest National Laboratory)

The second factor studied—strong filtration—also was very effective at reducing transmission of the coronavirus.

The team studied the effects of three levels of filtration: MERV-8, MERV-11, and MERV-13, where MERV stands for minimum efficiency reporting value, a common measure of filtration. A higher number translates to a stronger filter.

Filtration decreased the odds of infection in the connected rooms markedly. A MERV-8 filter decreased the peak level of viral particles in connected rooms to just 20 percent what it was without filtration. A MERV-13 filter knocked down the peak concentration of viral particles in a connected room by 93 percent, to less than one-tenth of what it was with a MERV-8 filter. The researchers note that the stronger filters have become more common since the pandemic began.

The most surprising finding of the study involved ventilation—the effect of what researchers call air changes per hour.  What’s good for the source room—cutting transmission risk within the room by 75 percent—is not so good for connected rooms. The team found that a rapid rate of air exchange, 12 air changes per hour, can cause a spike in viral particle levels within minutes in connected rooms. This increases the risk of infection in those rooms for a few minutes to more than 10 times what it was at lower air-exchange rates. The higher transmission risk in connected rooms remains for about 20 minutes.

“For the source room, clearly more ventilation is a good thing. But that air goes somewhere,” said Pease. “Maybe more ventilation is not always the solution.”

“There are many factors to consider, and the risk calculation is different for each case,” said Pease. “How many people are in the building and where are they located? How large is the building? How many rooms? There is not a great deal of data at this point on how viral particles move about in multiroom buildings.

“These numbers are very specific to this model—this particular type of model, the amount of viral particles being shed by a person. Every building is different, and more research needs to be done,” Pease added.

Filtration, outdoor air mixture, and air-exchange rate are a few of the factors in a multiroom building that affect levels of the virus that causes COVID-19.

(Photo by Roman Zaiets | Shutterstock.com)

Co-author Timothy Salsbury, a buildings control expert, notes that many of the trade-offs can be quantified and weighted depending on circumstances.

“Stronger filtration translates to higher energy costs, as does the introduction of more outside air than would usually be used in normal operations. Under many circumstances, the energy penalty for the increased fan power required for strong filtration is less than the energy penalty for heating or cooling additional outside air,” said Salsbury.

“There are many factors to balance—filtration level, outdoor air levels, air exchange—to minimize transmission risk. Building managers certainly have their work cut out for them,” he added.

U.S. Needs to Provide Aid to India

U.S. infectious-disease expert Anthony S. Fauci said Wednesday that the world has failed so far in tackling the global nature of the coronavirus pandemic with a suitably global response, leading to tragedies such as the current outbreak in India.

The nation of more than 1.3 billion is in the grip of a devastating surge, with more than 360,000 new cases in the past 24 hours — another global record — and 3,293 deaths, raising the toll past 200,000. Hospitals and crematoriums have been overwhelmed, and global assistance is only now slowly trickling in.

“The only way that you’re going to adequately respond to a global pandemic is by having a global response, and a global response means equity throughout the world,” Fauci told the Guardian Australia.

India’s coronavirus death toll topped 200,000 Wednesday with no indications of slowing down as shipments of foreign aid arrived in an effort to supplement dwindling medical supplies. The help, at least one official worried, will not address the thousands of patients turning up at already overrun medical facilities where staff is foregoing sleep and their own health in an effort to provide treatment.

"The current wave is particularly dangerous," Delhi Chief Minister Arvind Kejriwal told Reuters. "It is supremely contagious and those who are contracting it are not able to recover as swiftly. In these conditions, intensive care wards are in great demand."

According to India’s Ministry of Health, nearly 150 million doses of COVID-19 vaccine have been administered thus far, but the eligibility has not been opened to all 1.3 billion people. Currently, India is only vaccinating those over age 45. The country is relying on two vaccines for their rollout, namely the AstraZeneca jab and Covaxin, which is manufactured by Bharat BioTech Limited.

India is a major producer of the AstraZeneca jab, but has turned its attention elsewhere to address the crisis at home which in turn has hampered exports that other regions were relying on, such as Africa. The export ban is also a major blow to the COVAX initiative, which had relied on vaccine supply coming from India to supply dozens of low-income countries with jabs.

ASHRAE Provides Guidance for Protecting Voters

ASHRAE’s Building Readiness guidance provides practical information and checklists to help minimize the chance of spreading SARS-CoV-2, or other viruses at polling places in the future.

“Protecting our voters and poll workers from increasing the spread of COVID-19 at polling places is essential to protecting the health, welfare and safety of the entire population,” said Dennis Knight, ASHRAE Epidemic Task Force vice chair. “Many different HVAC system types are used in polling places, so adaptation of these guidelines to specific cases is necessary.”

Here is a summary of key general recommendations related to HVAC and water supply systems for polling places:

Space Selection: Select a space with a larger area for people to spread out, and if possible, a high ceiling to provide more volume for dilution. Consider space with operable windows if there are potential ventilation issues.

Inspection and Maintenance: Consider assessing the condition of systems and making necessary repairs. All building owners and service professionals should follow ASHRAE Standard 180-2018 “Standard Practice for the Inspection and Maintenance of Commercial HVAC Systems.”

HVAC Operation: The HVAC and toilet exhaust systems should be running when the space is occupied. If the HVAC system cycles on/off with the thermostat, consider running the fan constantly during occupied hours. If toilet exhaust is controlled by manual switches, leave the fan running for 20 minutes after use, or consider setting the switch to “on” and use signage that directs not to change the setting.

Ventilation: A good supply of outside air, in accordance with ASHRAE Standard 62.1-2019, to dilute indoor contaminants is a first line of defense against aerosol transmission of SARS-CoV-2. Pre- and post-occupancy purge cycles are recommended to flush the building with clean air. If the polling place is not ventilated or poorly ventilated and filter efficiency is not good, consider opening doors and windows, and consider re-locating all voting to the outdoors.

Air Distribution: Air flow distribution should not cascade air from the face of a person onto others, so take care in using personal fans.

Filtration: Use of at least MERV-13 rated filters is recommended, if it does not adversely impact system operation. If MERV-13 filters cannot be used, including when there is no mechanical ventilation of a space, portable HEPA air cleaners in occupied spaces may be considered. Also consider portable air cleaners in locations with more vulnerable staff.

Air Cleaning: Air cleaners such as germicidal ultraviolet air disinfection may also be considered to supplement ventilation and filtration. Technologies and specific equipment should be evaluated to ensure they will effectively clean indoor air without generating additional contaminants or negatively impacting space air distribution by creating strong air currents.

Temperature and Humidity: It is desirable to set the thermostat at the higher end of the comfort zone, 75-78ºF and maintain relative humidity between 40-60%.

Energy Use Considerations: In selecting mitigation strategies, consideration should be given to energy use as there may be multiple ways to achieve performance goals that have greatly different energy use impact. Control changes and use of energy recovery to limit or offset the effect of changes in outdoor air ventilation rate and filter efficiency may reduce or offset energy and operating cost penalties.

Water System Precautions: Buildings that have been unoccupied could have stagnant water, and water systems should be flushed to remove potential contaminants. Utilizing ASHRAE Standard 188 and Guideline 12 can help minimize the risk of water-borne pathogens such as legionella.

 

Chinese Researchers Create Charged Nanofiber Media with Silver for Anti-Microbial  Function

A  nanometer fiber filter membrane for filtering PM2.5,  was achieved with  multi-needle electrospinning equipment. By adding silver nitrate to the spinning solution, a polyvinylidene fluoride antibacterial nanofiber filter layer with high filtration efficiency and low resistance was successfully prepared on the traditional air conditioning filter meshes. Researchers found that four key factors affecting the filtration performance. They include ambient humidity, substrate meshes, voltage, and production rate. Among them, voltage and production rate are the key factors affecting the filtration performance. According to the development trend of multifunctional nanofiber membranes, the preparation of air conditioning filters with nanofibers as the main filter material was realized, producing air conditioning filter membranes with antibacterial and deodorizing functions. This article provides a reliable experimental basis and empirical reference for the preparation of nanofiber membranes based on multi-needle electrospinning technology.

https://aip.scitation.org/doi/10.1063/5.0009170

 

 

Filti Supplies MERV 16 Air Filters Using Nanofiber Technology

 

Filti, an air filtration and nanofiber technology company, has launched the 9500 Home Filter. The patent-pending 9500 Home Filter is an HVAC filter constructed using nanofiber technology, an N95-quality material that is proven to filter 95% of aerosolized, airborne particles – like COVID-19 – moving through the material.

Why is an N95-quality HVAC filter important? Air conditioners and heaters recirculate air throughout a room or building. Typically, HVAC filters are designed to trap dirt, debris, allergens and other impurities from recycling into the airflow. However, microscopic viruses, such as COVID-19 which studies have proven to be airborne, can easily move through most low-efficiency HVAC filters. Without a filter material that can successfully trap the smallest pollutants, aerosolized particles can be recirculated in the building.

"We wanted to provide people with a similar level of safety and protection within their homes that they get from wearing an N95 mask," says Dakota Hendrickson, co-founder of Filti. "We knew we could use our expertise in filtration to truly make a difference, and it was important to give people a way to better protect themselves and their families at home."

The replaceable filter is the only MERV 16 (Minimum Efficiency Reporting Value) residential HVAC filter on the market, according to the company. The extremely efficient yet highly air permeable nanofiber fabric, allows for an increased airflow ratio that won't put additional stress on a residential HVAC system.

The launch of the 9500 Home Filter is a return to Filti's core products after pivoting in March to produce N95-quality nanofiber material that could be made into face masks. After selling enough material to make nearly 15 million masks, the company now hopes its new N95-quality HVAC filter will provide the next level of protection nationwide.

Gyms Need Better Air Filtration Generally

The more intense the exercising, the more air you need to breathe in. And, as some studies show, the more people in the gym area, the more air pollution levels increase. Sources of this poor indoor air quality can be the occupants, dangerous chemicals from cleaning agents and building materials, the HVAC system, and inadequate ventilation and air filtration. In the case of Urban Apes, many of the climbers use magnesium-carbonate chalk to maintain a good grip while climbing. During peak periods, the total particle concentration measured in their gym therefore spiked to the dust-pollution levels at industrial premises. About half of these particles were the tiny PM1 particles that can get into the lungs and damage health. What this meant was high concentrations of fine dust in the air – as well as dry mouth and eye irritation from the dry air caused by the properties of the chalk. Urban Apes wanted to improve the gym’s air and protect the occupants’ health, while keeping energy consumption low

Camfil filters and air cleaners were brought in to deliver better air filter performance and achieve the best possible indoor air quality. The CC 6000 Air Cleaner, a free-standing unit, was placed in the large gym while the CC 2000 Air Cleaner, a wall mounted unit, was placed in a smaller room. The Benefits Included: • Significant improvement in indoor air quality and fewer dust particles in the room air (particle reduction in PM1, PM2.5 and PM10 of 70% and more) • Improved comfort levels for the athletes, guests and employees • Less cleaning of premises needed • Less pressure on their existing ventilation system and extended filter lifetime

 

Large French Retailer Installs Camfil HEPA Filters

A large French retailing group includes many hypermarkets brands, supermarkets and DIY shops. The group is present in many countries in Europe and between 3,000 and 4,000 people visit its headquarters and training center located in the Paris region every day. Further to the lockdown in France in March 2020 due to the COVID-19 pandemic, this large retailing group wanted to go on welcoming its staff to the premises of its headquarters in the best and safest way. The group wanted to be able to continue to train its new employees and franchisees in its hundred or so dedicated rooms. The control of the indoor air quality is a key factor for the health safety of the staff and trainees and also to help them feel protected, reassured, and confident. There were many different types of rooms involved: individual or two-person offices, open spaces, or large training amphitheaters. The customer did not want any work to be done in the rooms to clean the air.

To be able to guarantee the continuity of its activities and to ensure the safety of people with clean air free of airborne particles and viruses in the various buildings, Camfil proposed professional air purifiers equipped with HEPA H14 filters certified according to EN 1822. 

About 180 units of City M and 350 units of City S were installed to maintain good air quality in areas respectively of 45 square meters and 75 square meters. To ensure the filters’ filtration efficiency, each H14 filter has a serial number, is individually tested before it is shipped and delivered with its test report.

All the employees were able to work on the site as soon as September 2020. All training and the annual negotiation meetings with the franchisees are now carried out on the site. Once the health crisis is over, the staff will continue to benefit from clean air and reduce allergic reactions thanks to the ECARF (European Centre for Allergy Research Foundation)- certified City M and City S air purifiers (ideal for eradicating allergies). Improved air quality and fewer allergies contribute to less absenteeism and better productivity of staff.

According to INRS’ (National Institute for Research and Security), the City M air purifier includes HEPA filtration technology and is highly recommended to remove airborne contaminants such as the Covid-19 virus. A study financed by the Auvergne-Rhône-Alpes region on the City M equipped with HEPA H14 filters was carried out in January 2021. This study confirms the efficiency of Camfil HEPA H14 technology with filtration of up to 99.9% of the virus in 20 minutes of use (10 cycles of air recirculation) and total disappearance of infectious viruses on the filters at 48 hours. This allows for maintenance of the filters, without the risk of contamination of the operators.