This post is about what we know today about how to occupy commercial and public buildings, from offices to schools, in order to prevent the spread of the SARS-Cov-2 (the now designation for what had been the novel coronavirus 2019).
If in 1992, “it’s the economy, stupid” was the phrase coined as the message of the day, today as we face another surge in SARS-Cov-2 cases, it should be “it’s the ventilation, stupid.”
This is taken from a Zoom webinar I gave last week and is actually an update to my (.. admittedly very widely read) blog post on April 29, COVID-19 and the Risk from Recirculated Air in Buildings, but I must acknowledge, while this may refresh your recollection, there is little if any new guidance. And you might ask, ‘why advice from an attorney?’ to which I say, as an environmental attorney who reviews a lot of standards and codes, including about indoor air quality, I offer a perspective where others have not, including that my now much quoted April 29 blog post that was among the earliest writings on the topic.
In addition to more widely recognized transmission via direct contact with respiratory droplets generated by infected people or from contaminated surfaces, inhaling fine droplets and particles (often described as aerosols) being smaller than 10 microns is a principle pathway for infection of SARS-Cov-2. While uncertainties exist with respect to transmission pathways, it is beyond dispute that we cannot wait for 100% scientific certainty and owners of commercial buildings must now target airborne transmission within those buildings as part of any larger strategy.
Much of this can be easily implemented without much first dollar cost.
First and foremost, open the windows! If the building has operable windows, by all means provide ventilation by introducing outdoor air through those openings in the wall.
Increasing numbers of experts who study indoor air quality suggest the Centers for Disease Control and Prevention has placed insufficient emphasis on protection from small, virus laden, airborne droplets within the built environment. While others that deal specifically with buildings, like REHVA (the Federation of European Heating, Ventilation and Air Conditioning Associations) and ASHRAE (previously, the American Society of Heating, Refrigerating, and Air-Conditioning Engineers), have both acknowledged the indoors airborne hazard and in response described ventilation control measures.
Of course, the measures described here must be implemented by building owners in combination with increased disinfection of high touched surfaces, closing water fountains, and encouraging occupant behaviors like community wide use of face masks and hand washing.
Reasonable, but not certain inferences, including REHVA guidance, tell us:
Ventilation is key to reducing airborne transmission of SARS-Cov-2. Ventilation is the process of providing outdoor air to a space or building by natural or mechanical means to maintain the quality of indoor air. Appropriate building engineering controls are necessary and proper including avoiding air recirculation, enhanced by particle filtration and air disinfection, and avoiding overcrowding.
The most significant REHVA recommendation is “no use of recirculation” in any building with a mechanical ventilation system. However, the recirculation of indoor air is actually required by law, through application of standards incorporated into building codes, to save energy in the operation of buildings. But recirculated air can transport airborne contaminants including SARS-Cov-2 from one indoor place within a building to other areas in the building.
Particulate filters (MERV 13 filters and above) and disinfection equipment in recirculated air streams (such as ultraviolet germicidal irradiation and germicidal ultraviolet) can significantly reduce this risk, where feasible, but they need to be professionally installed and then regularly serviced.
Additionally, portable air cleaning machines may be beneficial in modest sized spaces.
Significantly, in a mechanically ventilated building, ventilation rates should be increased by HVAC system modifications. Increase air supply can be accomplished by extending operating times to start ventilation at least 2 hours before building usage, if not 24/7. Multiple matters need to be considered in addition to only the ventilation rate, including temperature control, relative humidity, air flow distribution and direction.
Again, if ventilation is provided by opening windows, by all means, open them. Theoretically at least, natural ventilation could introduce pollutants from the outside air, but ..?
Lest it be lost on anyone, ventilation plays a critical role in removing exhaled virus laden air, thus lowering the overall concentration and therefore any subsequent dose inhaled by the occupants.
Concomitantly, and while it might seem obvious, minimizing the number of people within an indoor space (from classrooms to restaurants and ..) accomplishes the same in limiting the spread of SARS-Cov-2.
Of import the science does not support plexiglass room dividers (.. becoming common in courtrooms and restaurants) for reducing risk of airborne transmission. Maybe they do NOTHING, but anecdotal evidence articulated by environmental engineers suggests they change the airflow patterns in the room and can cause pooling of air and hotspots, dangerously reducing ventilation effectiveness. Plexiglass barriers are only effective in preventing spray-borne drops from hitting you in the face if you are very close to a person (e.g., a sneeze guard for a cashier in a supermarket). It is like a shield to protect you from someone who is trying to spray you with a water gun.
World Health Organization curated studies describe that humidification and air-conditioning have no practical effect as coronaviruses are quite resistant to environmental changes and are susceptible only for a very high relative humidity above 80% and a temperature above 30 ˚C.
Note, duct cleaning has no practical effect and changing of outdoor air filters is not efficacious.
Arguably retro commissioning or otherwise tuning up HVAC systems could be advantageous or not.
But this is Not what is being done in the U.S. today. In fact, many local codes make increased ventilation illegal. ASHRAE 62.1, the standard specifying ventilation rates “to provide indoor air quality that is acceptable to human occupants and that minimizes adverse health effects” is widely suggested to not be enough in a SARS-Cov-2 period building, despite being mandated by many jurisdiction that have adopted the ICC codes that incorporate the standard by reference. And the use of no recirculated air, at all, is considered extreme by some, but likely necessary for a period of time (i.e., maybe until the population has been vaccinated?) in order to prevent the spread of coronavirus. ASHRAE’s leadership issued two statements last Spring in response to SARS-Cov-2, including, “changes to building operations, including the operation of heating, ventilating, and air-conditioning systems, can reduce airborne exposures.” But many building owners believe the ASHRAE epidemic task force, heavily weighted with academics, has been too slow to do anything (the European based REHVA acted months ago) and should do more, promptly providing direction on suspension of use of its standards, in particular those related to recirculated air and/ or provide greater guidance on filtering viruses.
State and local codes officials have, almost without exception failed, despite their more than 2,100 new SARS-Cov-2 related statutes, regulations and executive orders, to suspend code (BOCA, IECC, IgCC, etc.) requirements mandating use of recirculated air and the like. Code requirements for demand controlled ventilation should also be disabled during this pandemic.
Moreover, executive orders that close a restaurant or bar or other business after the building has been retrofitting to exchange indoor air 20 times per hour, avoid air recirculation, enhanced by particle filtration with MERVE 13 filters and air disinfection with UV-C technology, and additionally avoids overcrowding; are at best the wrong headed decisions of lazy policy making public officials and at worst unconstitutional takings without rational basis.
Make no mistake, “it’s the ventilation, stupid.”
Until effective vaccines exist and are in wide-spread use, enhanced ventilation in buildings will be key, and even more significant than the important social distancing including community masking, and hand washing, in limiting the spread of SARS-CoV-2.