Review building ventilation with facilities. Staff were worried about virus transmission via building HVAC systems. We contacted our facilities manager who told us they’re following special ASHRAE guidelines developed for COVID-19. Communicating this to staff made everyone less worried.
Based on what a library consortium did in Seattle, WA, a good first step is to talk with Public Works and/or Summit (our HVAC vendor) and see what type of filter is in use in each of our library buildings. Beyond that, working within ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) standards would be advised.
If you're interested, diving a bit deeper into the mechanics, which Public Works probably already knows...
Our current recommendation is to use a filter with a Minimum Efficiency Reporting Value (MERV) of 13, but a MERV 14 (or better) filter Is preferred.
Research has shown that the particle size of the SARS-CoV-2 virus is around 0.1 µm (micrometer). However, the virus does not travel through the air by itself. Since it is human generated, the virus is trapped in respiratory droplets and droplet nuclei (dried respiratory droplets) that are predominantly 1 µm in size and larger.
ASHRAE currently recommends using a minimum MERV 13 filter, which is at least 85% efficient at capturing particles in 1 µm to 3 µm size range. A MERV 14 filter is at least 90% efficient at capturing those same particles. Thus, the recommended filters are significantly more efficient at capturing the particles of concern that a typical MERV 8 filter which is only around 20% efficient in the 1 µm to 3 µm size range. Filters with MERV ratings higher than 14 would capture an even higher percentage of the particles of concern. High-efficiency particulate air (HEPA) filters are even more efficient at filtering human-generated infectious aerosols. By definition, a HEPA filter must be at least 99.97% efficient at capturing particles 0.3 µm in size. This 0.3 µm particle approximates the most penetrating particle size (MPPS) through the filter. HEPA filters are even more efficient at capturing particles larger AND smaller than the MPPS. Thus, HEPA filters are more that 99.97% efficient at capturing airborne viral particles associated with SARS-CoV-2.
I don't know if Hockessin is the same as other NCC branches, but I just had Wayne from Public Works check our air filters, and they appear to all be MERV 10, which according to ASHRAE, is below what is recommended for COVID (MERV 13+).
One of my staff works her main job as an adjunct professor in a nearby university. They have older buildings, but administration has informed staff that HEPA filters have been installed...so perhaps that might be an option, if there are concerns about air filtration in our libraries? As HEPA is even more efficient than MERV (see underline above).
But then again, upgraded MERV filters may be our best option
But installing HEPA filters may be technically untenable for most shopping centers, according to air filtration experts....
News outlets ran with the angle that Cuomo was mandating that malls install HEPA filters in order to reopen. But a statement put out later on June 29 clarified that the governor was announcing that "air conditioning filters with a Minimum Efficiency Reporting Value (MERV) rating capable of filtering COVID-19 particles or similar air exchange measures will be mandatory for large mall reopenings."