What is the best way to keep public spaces COVID-safe?

One of our Volunteers recently asked me if we should install plexiglass barriers to reduce the risk of exposure to COVID-19 in our Market. My partly cynical, partly exasperated response was, why? At WalMart and Target, you still have to step around the barrier to use the credit card machine, which seems to immediately nullify the entire purpose (and the massive investment)!

Looking at our checkout space, I’m sure it’s possible to engineer something that would be somewhat effective…but now that we know COVID-19 is airborne, wouldn’t an air purifier be better?

Here’s what the EPA has to say:

Air cleaning may be useful when used along with source control and ventilation, but it is not a substitute for either method. Source control involves removing or decreasing pollutants such as smoke, formaldehye or particles with viruses. The use of air cleaners alone cannot ensure adequate air quality, particularly where significant pollutant sources are present and ventilation is insufficient.”

“Engineering Controls” means modifying the physical space, or how people move in and through that space to decrease risk. The CDC recommends using a combination of the following controls to minimize exposure to COVID-19 in public spaces:

  • modify traffic flow to ensure six foot minimum distances between people at all times
  • install transparent shields in areas where maintaining a minimum distance of six feet is not possible
  • use signs, tape marks, and visual cues to remind people to keep an appropriate distance
  • increase percentage of outdoor air
  • increase total airflow supply to occupied spaces
  • consider using portable, high-efficiency particulate air (HEPA) filtration systems
  • limit contact if possible (delivery and curbside pickup)
  • clean and disinfect high touch surfaces
  • frequent hand washing

That’s great, but…

I’m just not finding any definitive evidence for which is better – like, if you’re a small business and you only have $200 to spend on “hazard controls”. The CDC’s “Hierarchy of Controls” helps businesses prioritize strategies to prevent the spread of COVID in the workplace.

Applying this flow chart to the Homestead Market, we could ELIMINATE or REPLACE the hazard by requiring/encouraging delivery or curbside pickup; both air filtration and plexiglass barriers are considered ENGINEERING CONTROLS; ADMINISTRATIVE CONTROLS, while easier to implement like encouraging social distancing, remote working, and staggered staffing are less effective than other interventions; and, of course, PPE, which everyone on the planet knows about by now (right?).

Remember the Vice-Presidential Debate?

The 2020 Vice Presidential Candidates were set to share a stage and participate in a live, in-person debate without masks. While they were maintaining a distance of more than twelve feet in a large auditorium, the only engineering control used that night was plexiglass.

“The problem is that a plexiglass barrier does not block aerosols; it only blocks spray,” says Donald Milton, an infectious disease aerobiologist at the University of Maryland School of Public Health. While plexiglass can block respiratory droplets coming from the candidates’ mouths, that kind of spray is more of a concern when people are within about 6 feet of each other, he says.


Virus-laden aerosols can linger in the air for hours, float around plexiglass partitions, and accumulate in poorly ventilated rooms. Jelena Srebric, a professor of mechanical engineering at the University of Maryland, told NPR, “The best way to really protect people is to remove viral particles at the source.” Meaning by wearing masks. Properly. And then, building their now-famous box fan/duct tape/HEPA filter contraption.

So, what is a small nonprofit to do?

After opening the windows…given the choice between one or the other, I would still choose an air filter (but with less cynicism and more researched confidence). Apparently, that plexiglass barrier would also be helpful, especially for those who do not wear their masks properly, or who do not have an effective mask.

Help us buy a Medical Grade air purifier!

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To help our Market stay healthy, open, and COVID-safe, we would like to purchase this $400 air purifier with Medical Grade H13 HEPA filters. We have $200 toward this from a local donor, please email arwen@theholistichomestead.org if you would like to help us purchase the rest!

Or, if you would like to contribute directly to getting plexiglass barriers built for our Market, click here to made a secure, fast, and direct donation today! Thank you!

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