Healthy Indoors | 19
all mixed up in the room. When you have
fans or people walking in a room, the air
gets even more mixed up.
If your focus is removing pollutants from
the room, it's best to assume the new and
old air get at least somewhat mixed up be-
fore exiting.
Where'd you get that air?
Although he didn't mention it, I believe
Poppendieck was talking about the new
air being ventilation air from outdoors.
But air can enter a room in different ways.
Many of us live in homes with forced-air
heating and cooling systems that recircu-
late air throughout the home. If you have
good filtration integrated with such a sys-
tem, that can help, too. I've written quite a
bit about using filters rate at MERV-13 or
higher, and they can reduce the pollutants
in your indoor air significantly. Fibrous me-
dia air filters won't remove pollutants in the
gas phase, but they can capture the partic-
ulates, including the droplets and aerosols
carrying the coronavirus.
Then there's the air that infiltrates into
the house from outdoors or from buffer
spaces, like the garage, crawl space, and at-
tic. Contrary to what some people still be-
lieve, a house does NOT need to breathe.
Breathing dead possum from the crawl
space or air sucked through a dead squirrel
in the attic is not as good as straight out-
door air. The best thing to do is air seal the
house as much as possible and rely on oth-
er ways to improve your indoor air quality.
Allison Bailes
Allison Bailes of Atlanta, Georgia, is a speaker, writer, building
science consultant, and founder of Energy Vanguard. He is also the
author of the Energy Vanguard Blog. You can follow him on Twitter
at @EnergyVanguard.
Mechanical whole-house ventilation sys-
tems help improve indoor air quality by in-
troducing outdoor air into the house. If the
coronavirus is the only pollutant you're con-
cerned with, all outdoor air is good air. But
you should be concerned with more than
just this one pollutant. In most homes, the
majority of the small particulates that are
most dangerous to health (PM2.5) comes
from outdoors. During wildfires, there's a
whole heck of a lot of particulates in the
outdoor air, so good filtration must be part
of your IAQ strategy. Also, in some areas,
you may need to pay attention to your out-
door air quality on a regular basis and pick
the best times to introduce outdoor air.
Room, Zone, Building
The last issue here is scale. Poppendieck's
tweet focused on a room, which is the right
scale for a quarantine room or a room
where you might bring other people into
your house for a while. But all the air in your
house is connected, and that can help. If, for
example, you set up a quarantine or enter-
tainment room with an exhaust fan or ex-
haust vent for an energy or heat recovery
ventilator (ERV or HRV) and your outdoor
air is supplied to another part of the house,
you'll come close to having displacement
flow. That means you'll be removing rela-
tively unmixed air that has a lot of the orig-
inal pollutants in it.
Air flow through a building is a complex
subject. If you're a researcher, diving in and
understanding that complexity is important.
If you're a homeowner, teacher, or building
supervisor, what's most important is to look
for ways to increase the amount of ventila-
tion in poorly ventilated spaces, clean the
air with MERV-13 or higher filters, and block
infiltration from garages, crawl spaces, attics,
or other places that have worse air than is in
the house already. You can also use portable
air cleaners, like the Comparetto Cube, to
help remove pollutants in a room.
David Byrne and the Talking Heads
were ahead of their time musically, but did
you know they were early advocates for
good indoor air quality? Here's what they
had this to say in the song Air:
Air can hurt you too
Air can hurt you too
Some people say not to worry about the air
Some people never had experience with...
Air...Air
So, pay attention. Changing the air in
your house, office, or classroom is critical.
But how quickly are you really removing
the old air with all its pollutants? And what
are you replacing it with? Ventilation, filtra-
tion, source control, and moisture control
are your best options for good indoor air
quality.
Some 'a you people just about missed it!
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