The weather has started getting cold and for some people that means it’s time to turn on more indoor fans.
Sounds weird? You bet. But COVID-19 has scrambled pretty much everything else, so why not indoor ventilation habits?
The idea is to create your own virus-catcher by putting a filter in front of a box fan somewhere in the room or buying a mobile ventilation unit with specialty filters, like R2D2 with a medical degree. Eventually, the thinking goes, floating bits of aerosol moisture from everybody’s breathing will be pulled in and get trapped along with any COVID viruses they contain.
Blocking the airflow over an electric motor isn’t usually a good move so the EPA tested the filter-and-box-fan setup to make sure it wasn’t a fire hazard, spurred by the growing use of them to keep wildfire smoke out of homes in the West. No worries, they said in a press release: “Fan temperatures remained below safety standards and no tests revealed any observable fire hazards.”
So they’re safe. But are they effective?
There’s no question that ventilation is a key to keeping indoor space healthy. That’s why HVAC (“heating, ventilation, air conditioning”) systems have filters. The Concord School District, for example, has more than 1,000 filters in all the furnaces and blowers throughout its schools and other buildings, and they all get changed quarterly.
The Centers for Disease Control puts ventilation at the center of its recommendations for controlling COVID-19 indoors. But there’s a catch.
I’ll quote from the CDC website: “The room described in Example 2 is now augmented with a portable HEPA air cleaning device with a smoke CADR of 120 cfm (Qhepa = 120 cfm). The added air movement within the room improves overall mixing, so assign k = 3. Question: How much time is saved to achieve the same 99% reduction in airborne contaminants by adding the portable HEPA device to the room?”
If the system isn’t big enough, doesn’t move enough air, there’s no guarantee that the room is much safer.
This is particularly true because air movement is very complicated. It’s an example of fluid dynamics, a topic so gnarly that it makes physics students weep and change their major to psychology.
Unless you hire a professional to run smoke tests or blower tests to determine how air is actually moving in a room there’s no guarantee that all of the air, or even much of it, will pass through your unit and get cleaned. It feels good to bungee-cord a MERV16 filter over a box fan you pulled out of the garage and put it on a convenient table, or have a mobile ventilation unit blinking away in the corner where people won’t bump into it, but that’s no guarantee.
The poster child for caution occurred in May in California when an unvaccinated teacher who had symptoms pulled her mask down to read to a class and ended up infecting 12 of her students who were all fully masked – even though the room had open windows on two sides plus “portable high-efficiency particulate air filters.”
The result of all this is that we by all means work to improve ventilation in our homes and offices or businesses. But we have to careful not to fool ourselves that it’s a substitute for all the other COVID-19 safeguards we need: Vaccination, masking in crowds, basic sanitation.
And getting vaccinated – did I mention getting vaccinated? Don’t forget that one.
For coronavirus-related information and updates throughout the week, visit concordmonitor.com/coronavirus.
How are we doing on vaccinations? Maybe a little uptick, but a very little one.
The state’s tally of how many state residents become fully vaccinated each week peaked back in April at almost 10,000 and went steadily down through July to below 300 a week, which is almost nothing in a state with 1.35 million people.
Since the beginning of September, the weekly tally has edged up from 140 to almost 180 a week. That’s still painfully low but it might be an indication that vaccine requirements from companies are starting to have an effect.
In general, though, there’s still a 45% chance that any New Hampshire resident you encounter is unvaccinated. Keep that in mind.
What’s the trend on the spread and impact of the disease? Not good, but not getting worse.
The state’s data makes it clear: We’re in slightly worse shape as we were at the peak of the second surge in April.
At the moment the daily count of new cases has averaged 455 over the past two weeks, compared to a high of 434 in April; there are 144 people in the hospital with COVID-19 compared to an April peak of 133; and almost exactly 2 people are dying each day on average compared to 1.6 in April.
On the other hand, none of those numbers have increased in the past week even as temperatures have driven more of us indoors, so maybe we have hit a new peak. Maybe vaccination will prevent a copy of last winter when everything got worse in December and much worse in January.
(David Brooks can be reached at 369-3313 or dbrooks@cmonitor.com or on Twitter @GraniteGeek.)
