The weather has started to get cold and for some people it means it’s time to turn on more indoor fans.
Sounds weird? You bet. But COVID-19 pretty much messed up everything else, so why not indoor ventilation habits?
The idea is to create your own virus catcher by placing a filter in front of a box fan somewhere in the room or by buying a mobile ventilation device with special filters, such as R2D2 with a medical degree. At some point, it is thought, floating pieces of aerosol moisture will be sucked in from everyone’s breath and trapped along with the COVID viruses it contains.
Blocking airflow via 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 on by the increasing use of them to control wildfire smoke keep away from the houses to the west. Don’t worry, it says in a press release: “The fan temperatures remained below the safety standards and no tests revealed any identifiable fire hazards.”
So you are safe. But are they effective?
There’s no question that ventilation is a key to keeping indoor spaces healthy. That is why HVAC (“heating, ventilation, air conditioning”) systems have filters. The Concord School District, for example, has more than 1,000 filters in all ovens and fans in its schools and other buildings, all of which are changed quarterly.
The Centers for Disease Control puts ventilation at the center of its recommendations for combating COVID-19 indoors. But there is a catch.
I quote from the CDC website: “The room described in Example 2 is now being expanded with a portable HEPA air purifier with a smoke CADR of 120 cfm (Qhepa = 120 cfm). The additional movement of air in the room improves the overall mix, so assign k = 3. Question: How much time is saved to achieve the same 99% reduction in airborne pollutants when the portable HEPA device is built into the room? ”
If the system isn’t big enough, not moving enough air, there is no guarantee that the room will be much safer.
This is especially true because the movement of air is very complicated. It’s an example of fluid dynamics, a subject so gnarled it makes physics students cry and switch their major to psychology.
Unless you hire a professional to run smoke tests or fan tests to see how the air actually moves in a room, there is no guarantee that all or any air will pass through your device and be purified. It feels good to attach a MERV16 filter over a box fan pulled from the garage with bungee cord and place it on a practical table, or to have a mobile ventilation device blink away in the corner where people won’t come across it, but it is not a guarantee.
The flagship of caution occurred in California in May when an unvaccinated teacher who was experiencing symptoms pulled down her mask to read to a class and ended up infecting 12 of her students, all of whom were completely masked – even though the room was open on two sides Windows had plus “portable high-efficiency particulate air filters”.
The result of all of this is that we are definitely working on improving ventilation in our homes and offices or businesses. But we have to be careful not to delude ourselves that it is a substitute for any other COVID-19 protective measures we need: vaccination, masking in crowds, basic sanitation.
And get vaccinated – did I mention I was vaccinated? Do not forget that.
Information and updates on the coronavirus during the week can be found at concordmonitor.com/coronavirus.
How are we with vaccinations? Maybe a small upward trend, but a very small one.
The number of the state’s how many state residents are fully vaccinated each week peaked at nearly 10,000 in April and steadily declined to below 300 per week by July, which is almost nothing in a state of 1.35 million people.
Since the beginning of September the weekly number has increased from 140 to almost 180 per week. That’s still painfully low, but it could be an indication that companies’ vaccine requirements are having an impact.
However, in general, there is still a 45% chance that every New Hampshire resident you encounter is unvaccinated. Keep that in mind.
What is the trend in the spread and effects of the disease? Not good, but not worse.
The state’s data make it clear: We’re in slightly worse shape than we were at the peak of the second surge in April.
Currently, the daily number of new cases has averaged 455 for the past two weeks, compared to a high of 434 in April; 144 people are hospitalized with COVID-19, compared to a high of 133 in April; and on average, almost exactly 2 people die every day compared to 1.6 in April.
On the flip side, none of these numbers have risen in the past week, even though temperatures have pushed more of us into the house, so we may have hit a new high. Perhaps the vaccination will prevent a copy from last winter when things got worse in December and much worse in January.
(David Brooks can be reached at 369-3313 or [email protected] or on Twitter @GraniteGeek.)