There are many paths to reducing risks associated with the transmission of COVID-19. Infection control is about reduction of risk, not elimination of possibility. A broad, systems approach, with purposeful redundancy, is required. HVAC is just one part of the equation. 

We’ve seen much focus on using social distancing to limit airborne transmission by expelled droplet nuclei between people in close proximity. That is an important measure. However, droplet nuclei quickly get smaller and may also stay airborne long enough to be entrained into the HVAC system. To prevent it from becoming a means of distribution, MERV 13+ filtration is being recommended by ASHRAE, as well as other measures, such as UVC. Dynamic has a range of systems that can help in the fight against COVID-19.

The Dynamic V8 provides MERV 15 performance, with lower pressure drop and a far longer service life than passive alternatives. In the normal course, the Dynamic V8 has many advantages over passive filters. It is widely used as both a retrofit and in new construction in critical applications such as laboratories, healthcare, military installations, and art museums.  In the current situation, the Dynamic V8 has several specific advantages:

• Low pressure drop allows for retrofit into a wider range of systems:  The higher static pressure inherent in high-efficiency passive filtration upgrades make them difficult or impossible in many instances. The Dynamic V8, with its low static pressure, no pre-filter, and flexibility of design allow it to be used in many situations where passive filters cannot be used. Dynamic V8s can be permanently mounted in AHUs for upstream or downstream access; in slide-out racks for package equipment; or duct-mounted in VRF applications. With a clean static pressure of typically less than .3”w.g., there a lot of options.
  
  
• Longest Maintenance Cycle:  In actual installations, Dynamic V8s without pre-filters will last 2-5 years between changeouts. Again, in the normal course, this means less energy, less landfill, and less labor. In the current crisis, maintenance staffs are stretched thin and changing filters is not only time-consuming, it is also dangerous.
  
  
• Positive Seal:  The seal of any filter is critically important to its effectiveness in the field. A small gap can allow an astonishing amount of unfiltered air to get around the filter. The Dynamic V8 has a positive seal throughout its construction to eliminate bypass. The media pads seal inside the frames; the frames seal to the assembly; and the assembly seals in the rack.
  
  
• A Deeper Cleaning of the Air:  The MERV test is a useful tool for comparing filtration options.  However, it is not the whole story: 
  
  Firstly, it does not take into consideration particles below 0.3 micron.  Secondly, it does not consider changes in particle size distribution.

Like all Dynamic polarized-media air cleaners, the Dynamic V8 uses an active, non-ionizing, DC voltage to create an electrostatic field that polarizes both the media fibers and the particles in the air. This gives Dynamic Air Cleaners the ability to agglomerate and collect ultrafine particles.  For example, in an in-situ test in an urban environment, a Dynamic V8 Air Cleaning System in a commercial building yielded indoor levels of ultrafine particles (0.015-0.1 micron) that were 92 to 99% lower than outdoor levels.

UVC has been used for decades to inactivate molds, bacteria, and viruses in air and water.  Most UVC in HVAC applications is optimized to inactivate biologicals that might be on the surfaces of coils and in drain pans. Dynamic Sterile Sweep® UVC Systems couple high output 254nm UVC lamps with translucent glass media in Dynamic Air Cleaners, in a “Catch, Hold, Kill” configuration optimized for airborne inactivation.  This provides the necessary contact time for UVC to work.  90% of captured bacillus subtilus is inactivated after 5 minutes, and 99% after 20 minutes. These systems were part of the Anthrax clean-up at the U.S. Postal Service and continue to be the basis of design in many Federal mailroom applications. More commonly, the Sterile Sweep and 1” or 2” V-Banks are used as a frequent pre-filter for Dynamic V8s in hospital applications.

Again, infection control is about reduction of risk, not elimination of possibility. A holistic approach may include:

• MERV 13+ air filtration.
• UVC germicidal systems with sufficient intensity, proximity, and dwell time.
• A well-sealed HVAC system.
• Localized supplemental air cleaning systems.
• Increased ventilation rates and airflow patterns that draw contaminants out of the breathing zone.
• Isolation and negative pressurization of the areas where the sick are treated.
• Personal protection of face, eyes, nose and mouth.
• Personal hygiene and frequent handwashing.
• Frequent sanitation of surfaces.
• Social distancing.

Dynamic Air Quality Solutions has been designing and manufacturing air cleaning systems for over 35 years and is known for high-efficiency air filtration with low pressure drop—allowing for retrofit into air handlers that might not have the fan horsepower for high-efficiency passive filters. The company also offers germicidal UVC systems. Both product lines have been used for decades in high-impact medical, laboratory, and pharmaceutical applications.

We are committed to doing everything we can to help fight this pandemic.

ASHRAE Building Readiness Guide 18 Aug 2020

Yes, the Coronavirus Is in the Air  by Dr. Linsey C. Marr, The New York Times 30 Jul 2020

Hygiene Theater is a Huge Waste of Time by Derek Thompson, The Atlantic 27 Jul 2020

ASHRAE Reopening Guide for Schools and Universities 22 Jul 2020