CATER Mask Decisions

January 26, 2021

HVAC, Fan Filter Units, Air Purifiers and Safe Bubbles

Benefits of Latest ASHRAE Recommendations Explained by enVerid

Philadelphia Reopens Restaurants but has a Self-Certification Process to Expand to 50% from 25%

Michigan Allows Indoor Dining with Certification Process

Chicago Now Allows Indoor Dining

More High Efficiency Masks

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HVAC, Fan Filter Units, Air Purifiers and Safe Bubbles

The latest ASHRAE recommendations can be part of the safe bubble concept. The safe bubble concept includes a rating which assures those entering the bubble that they will be as safe as mandated by local regulations.

If companies such as SGS can validate that sanitation meets the guidelines they can validate air quality. The mandate for 25% occupancy was used in the Alert yesterday as an example. To meet this mandate a facility must show that it has no more risk than if it reduced occupancy to 25%.  So this is the equivalent of a 75% risk reduction from full occupancy.

Instead of the typical cloth mask, if everyone entering the bubble has a tight fitting efficient mask the risk will be reduced by 99%. But people will not wear their masks at all times and some may not wear them properly. Most importantly people need to take off their masks to eat and shower. They also desire to remove their masks when in areas of low risk.

HVAC and local air filtration can be used to offset the vulnerabilities of mask wearing. People  will need to remove their masks in lunch rooms. Local air purifiers and particularly fan filter units are valuable in reducing risk in this area. When an individual is in a relatively isolated work space he can remove his mask if the HVAC system is adequately controlling and cleaning the air he breathes.

In lobbies, elevators, and other spaces where diverse people will be mingling in relatively close quarters air cleaning will contribute significantly to risk reduction.

A validating firm such as SGS is not going be able to assess absolute risk because this is a function of the varying viral load in the community. However it can creditably determine the relative risk reduction. 

Mask use and efficiency plays such a crucial role it has to be the foundation of the risk assessment. The local dust hood in industrial ventilation is the equivalent. It is unthinkable that you would let lots of dust escape at the source and rely solely on HVAC to purify the air.  Instead plants go to great lengths to minimize fugitive dust. The COVID risk assessment has to start with the mask effectiveness and then assess ambient air cleanliness.

The Respirable Crystalline Silica Rule by OSHA is an example. Recent OSHA requirements increase the amount of dust control which is required. But the rule is written in a manner to coordinate masks and air filtration.

• Determine the amount of silica that workers are exposed to if it is, or may reasonably be expected to be, at or above the action level of 25 μg/m3 (micrograms of silica per cubic meter of air), averaged over an 8-hour day.

• Protect workers from respirable crystalline silica exposures above the permissible exposure limit (PEL) of 50 μg/m3, averaged over an 8-hour day.

·         Use dust controls and safer work methods to protect workers from silica exposures above the PEL

·         Provide respirators to workers when dust controls and safer work methods cannot limit exposures to the PEL

The difference between COVID and silica dust risk mitigation is that in one case you use masks when you cannot otherwise control the risk. In the other you discard masks when you can. For COVID you can discard your mask when you can easily control COVID with HVAC.

The investments in filtration will be permanent and will also provide protection from indoor air pollutants. The mask demand will fall as the virus load drops. The following graph shows that masks provide most of the protection when the viral load is high but can be used less frequently as the viral load drops and installation of air purification improves.

Benefits of Latest ASHRAE Recommendations Explained by enVerid

enVerid Systems, fully supports the ASHRAE Epidemic Task Force's (ETF) updated "Core Recommendations for Reducing Airborne Infectious Aerosol Exposure," and calls on office, school, and institutional building managers to reevaluate their HVAC strategies for mitigating COVID-19 in light of the updated guidance to ensure desired exposure reduction while minimizing associated energy penalties.

On Jan. 6, 2021 ASHRAE's ETF posted a refined and concise summary of its recommendations across its many detailed guidance documents, including its Commercial Guide and School Guide. As stated in the ASHRAE press release, the Core Recommendations are "based on the concept that ventilation, filtration and air cleaners can be combined flexibly to achieve exposure reduction goals subject to constraints that may include comfort, energy use and costs."

The Core Recommendations for Ventilation, Filtration, and Air Cleaning are the following:

• Provide and maintain at least required minimum outdoor airflow rates for ventilation as specified by applicable codes and standards.
• Use combinations of filters and air cleaners that achieve MERV 13 or better levels of performance for air recirculated by HVAC systems.
• Only use air cleaners for which evidence of effectiveness and safety are clear.
• Select control options, including standalone filters and air cleaners, that provide desired exposure reduction while minimizing associated energy penalties.

"With this important update, ASHRAE makes clear that buildings can achieve safe air exchange rates with a mix of ventilation, filtration, and air cleaners to mitigate aerosol transmission," said Christian Weeks, CEO of enVerid Systems. "Additionally, the ETF emphasizes that energy expenditure is a critical factor in determining an optimal HVAC strategy for COVID mitigation. We applaud the ETF's rigorous effort to evolve their recommendations to account for key operational considerations, and we encourage building managers to reevaluate their HVAC COVID-19 strategies to align with ASHRAE's updated guidance to deliver safe indoor air without the high energy penalty of ventilation-only approaches."

In the early days of the pandemic, the ASHRAE ETF released preliminary guidance that called for maximizing outside air ventilation. This strategy has several drawbacks including high energy penalties and increased carbon emissions. During an October webinar, Prof. William Bahnfleth, Chair of ASHRAE's Epidemic Task Force, explained that initial guidance from ASHRAE was very conservative without consideration for cost, operational, and seasonal weather impacts. Over time the ASHRAE ETF has evolved its guidance, and the Core Recommendations refine the ETF's findings into a streamlined prescription to mitigate the transmission of infectious airborne aerosols in commercial buildings.

According to Prof. Bahnfleth, "ASHRAE's Core Recommendations are based on an equivalent clean air supply approach that allows the effects of filters, air cleaners other removal mechanisms to be added together to achieve an exposure reduction target." Experts from Harvard Chan School of Public Health recommend six air changes per hour (ACH) as the ideal exposure reduction target for schools. Six ACH means the air inside building spaces will be exchanged for clean air once every 10 minutes. Clean air is defined as outside air or recirculated air that has been filtered by high-efficiency filters such as MERV-13 filters and local HEPA filters.

"We welcome the new ASHRAE ETF Core Recommendations, and the emphasis on a flexible combination of HVAC strategies to address indoor air quality allowing important considerations such as energy penalties, outside air quality and other factors to be part of the equation," said Robert Ioanna, Senior Principal at Syska Hennessy. "Today's priority is halting transmission of SARS-CoV-2. Tomorrow's will be ensuring HVAC systems address the dual priorities of pandemic proofing and maximizing energy efficiency – with the end goal of high IAQ, lower operating costs and reduced carbon emissions." 

enVerid continues to share a range of resources to help inform building engineers, owners, and consulting engineers about IAQ, infectious aerosols, and contaminants of concern.

Most recently, enVerid published the enVerid COVID-19 Energy Estimator, a free, open-source tool to help building owners, mechanical engineers, and facility managers evaluate the risk, costs, and carbon impacts of different ventilation and filtration approaches to reopen buildings safely. The Energy Estimator shows that installing high-efficiency filtration can be as effective and lower cost than increasing ventilation rates to achieve target air exchange rates to reduce bioaerosol exposure risk.

Additional resources for building managers and engineers include a White Paper on filtration and ventilation, a Guide for Improving Classroom Air Quality for COVID-19 Mitigation and a Webinar Series on COVID-19 & IAQ: New Best Practices that features ASHRAE ETF experts.

enVerid Products

enVerid's HVAC Load Reduction^® (HLR) technology saves money for commercial property owners and occupiers by enabling the reduction of outside air without compromising indoor air quality. HLR technology does this by scrubbing indoor air of all molecular contaminants of concern. ASHRAE Standard 62.1 defines two procedures for mechanical ventilation: the Ventilation Rate Procedure (VRP) and the Indoor Air Quality Procedure (IAQP). Unlike VRP, which defines ventilation requirements based on space size and occupancy without accounting for the efficiency benefits of air cleaning technologies, IAQP is a performance-based ventilation approach that allows for lower outside air (OA), and therefore lower energy expense when air scrubbing technology is used.

Designing HVAC systems using IAQP combined with sorbent-based air cleaning and high-efficiency filtration significantly reduces first- and operating costs without increasing the risk of airborne transmission of viruses.  For illustration, in a 100,000 ft² office building in New York City, by reducing rather than increasing 10,000 CFM of OA, $500,000 can be saved on combined first costs and 20-year operating costs without increasing airborne virus transmission risk.

The enVerid Air Purifier is a ceiling mounted HEPA air filtration system with an ultraviolet germicidal irradiation (UVGI) sterilization lamp that has been shown to capture 99.99% of viruses including a surrogate for the COVID-19 virus. A low-cost, easy to install, and energy efficient solution, the enVerid Air Purifier is ideal for offices, classrooms, retail stores, and other commercial applications seeking to boost effective air changes per hour.

Philadelphia Reopens Restaurants but has a Self-Certification Process to Expand to 50% from 25%

The safe bubble concept with validation is an alternative to the Philadelphia self-certification which will allow restaurants to expand from 25% to 50% occupancy

Starting Saturday, indoor dining can resume at Philadelphia restaurants after the city lifted a nearly two-month ban due to the spread of the coronavirus.

They can only operate at 25% capacity and with no bar seating. No more than four people can sit at a table, and they must be from the same household. Guests must wear masks unless they're actively eating or drinking.

Restaurants must go through a self-certification process to go to 50% capacity, otherwise, they are limited to 25%.

Philadelphia is also allowing other "riskier" settings and activities to resume. Theaters and performance spaces are allowed to reopen with a cap on the total number of attendees, including staff, of 10 percent maximum occupancy. If the maximum occupancy is unknown, allow 10 persons per 1,000 square feet. Everyone in attendance must be masked, and no food or drink is allowed.

the 1 person/100 ft2 is another risk yardstick which instead of occupancy could be used as the risk reduction equivalent.

Michigan Allows Indoor Dining with Certification Process

Michigan is applying the “Pull” portion of the Push-Pull initiative relative to restaurant risk reduction. By voluntarily achieving certification these restaurants will be featured on the State safe dining website.

The Michigan order will allow for indoor dining at restaurants with certain requirements; concessions at casinos, movie theaters and stadiums; personal services requiring mask removal; and non-residential gatherings of up to 10 people from two households. 

The new order will last three weeks, until Sunday, Feb. 21.  

The voluntary MI COVID-19 Safer Dining program allows food service establishments to become certified by having their ventilation system inspected and submitting their inspection report to the state indicating they are optimizing airflow.

Once certified, businesses will be featured on the Michigan.gov/covidsaferdining website and receive a copy of their certification to post at their establishment to alert diners of their participation. 

Funding is proposed for food service establishments to participate as part of the $10 million included in the recent supplemental budget request for restaurant supports administered by the Michigan Occupational Safety and Health Administration.

Chicago Now Allows Indoor Dining

Chicago and suburban Cook County are officially open for indoor dining for the first time since late October under coronavirus pandemic restrictions, officials said Saturday morning.

The announcement that the two regions have moved to Tier 1 means restaurants will reopen for indoor service — but at 25% capacity or 25 people per space, whichever is fewer. Bars and restaurants opening for indoor service will also be held to a raft of other restrictions.

According to guidelines, tables will be limited to no more than four people indoors or six people outdoors. Diners must wear a face covering except with seated and eating or drinking, and they must put it back on when interacting with servers, under Gov. J.B. Pritzker’s August rules. The Tier 1 restrictions also state tables must be spaced 6 feet apart; indoor service will be limited to a maximum of two hours; and bars and restaurants must close by 11 p.m. Bars that do not serve food cannot go back to indoor service yet

More High Efficiency Masks

Here are additional masks with some degree of filtration efficiency but not necessarily a fight fit

WWDOLL KN95 face mask (25-pack)

Photo courtesy of Amazon.

Featuring five layers, a foldable design and an adjustable nose bridge, this mask is available in black for a different look than the standard white color.

Amazon $39.99 (for 25-pack)

Dasheng N95 mask (5-pack)

This NIOSH-approved mask has dual-point welded straps and an adjustable nose grip for a secure fit.

Lowes $19.99 (for 5-pack)

SupplyAid KN95 protective face mask (5-pack)

Photo courtesy of The Home Depot.

Featuring a five-layer design, this mask has an adjustable nose bridge and ear bands to prevent shifting during movement.

The Home Depot $16.98 (for 5-pack)

Bielcor N95 face mask (20-pack)

Photo courtesy of Sears.

With a rigid outer shell, this mask was designed for humid or moist environments. As a NIOSH-approved mask, it can fit adults or children.

Sears $23.40 (for 20-pack)

World Tech KN95 face mask (2-pack)

Photo courtesy of Ace Hardware.

This mask features bacteria and filtration systems with an adjustable nose bridge and ear bands.

Ace Hardware $5.99 (for 2-pack)

AOK N95 face mask (1-pack)

Photo courtesy of wellbefore.com.

If you’re looking to order a single mask, this option is for you. It’s not only NIOSH-approved but has a cup shape and two nose bridges for a close fit. It comes in various sizes to fit different ages and face shapes.

wellbefore.com $2.99 (for single mask)

ChiSip KN95 face mask (20-pack)

Photo courtesy of Amazon.

Featuring five layers, an adjustable nose bridge and ear loops, this mask is sold in four colors... even pink!

Amazon $39.99 (for 20-pack)

Makrite N95 face mask (20-pack)

Photo courtesy of Clinical Supplies.

Designed to fit smaller faces, this NIOSH-approved mask has an adjustable nose bridge and elastic loops that go around the wearer’s head.

Clinical Supplies $99.99 (for 20-pack)