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A good-air and bad-air day comparison

PostPosted: Wed Oct 15, 2008 1:31 pm
by Wilberforce
A good-air and bad-air day comparison

When a building is being internally heated, two things happen: The relative humidity drops. Also, the air
expands when heated, becoming less dense. Because the indoor air has lower density, it has lower pressure.
This means that there will always be a cold draft somewhere in the building, regardless of how well-sealed
the weather stripping/caulking is thought to seal windows and doors. All a homeowner can hope to do is to
reduce excessive drafts. Unless a building is hermetically sealed (as a can of soup is) there will always be
some leakage, to equalize indoor/outdoor pressures. This effect becomes more pronounced as outdoor
temperatures fall and/or indoor temperatures rise. One cannot control the outdoor temp, but the indoor
temp can be controlled. Setting the heating thermostat a few degrees lower may help erase some of that
temperature differential.

Thus indoor pollution is a function of outdoor pollution. That is, when outdoor PM and CO levels rise, so do
indoor levels of PM and CO. One can run a HEPA air cleaner continuously in order to remove (but not eliminate)
PM. But a means must be found for sequestering carbon monoxide which has seeped in through those gaps
around home portals. As I've said, there is no perfect seal in the average home. People who have complained
about nausea and headache from their neighbor's fireplace smoke exhibit the classic symptoms of carbon
monoxide poisoning. The best way to stop that is to extinguish the fire, which is the source of that carbon monoxide.

Here are some of my own PM readings. Set 1 data is from a EPA-certified 'bad-air' day; set 2 is from a 'good' day.
Comparisons of outdoor readings and corresponding indoor ('clean-room') readings:

                                            fine (0.5 µm)            coarse (2.5 µm)
(1a) Bad air day outdoor        2700                            200
(1b) Bad air day indoor            280                              40

(2a) Good air day outdoor        300                             40
(2b) Good air day indoor            80                              15

Notice the indoor clean room (with the always-running HEPA filter) readings are considerably lower than the
outdoor readings. My air cleaner is just an inexpensive Sears unit. I'm sure an expensive version could do
an even better job than this. It is a good idea to take a particle counter to the store with you when you
are going to purchase a new air cleaner. Some are better than others. Take two readings: one at the
running unit's intake, an another at the output. The output reading should be about of one-tenth (or less)
than that of the intake. This means that the unit's efficiency is about 90% particulate removal. (My cheapie
unit is only about 60% removal and I get good indoor readings; see the above data)

My next instrument purchase will be a carbon monoxide meter. I will keep you posted on that.

measuring and filering

PostPosted: Wed Oct 15, 2008 4:24 pm
by Ernest Grolimund
I bought a $300 Sears envirosense air cleaner with two opacity meters, a hepa filter and a charcoal filter for toxic gases like carbon monoxide perhaps and it was overwhelmed by the smoke I was up against. It told me that too. It was always reading red or very unhealthy. But the IQ Air air cleaner gets everything. Of course I have talked to neighbors and the smoke is less and it's not flying thick yet. I have some carbon monoxide detectors and they never went off so I wouldn't be worried about just carbon monoxide. CO is light but benzene and the other 200 air toxic gases are heavier than air. Activated charcoal gets the most of them that you can get. We also have a canary in our coal mine of a house in our asthmatic daughter. Not one bad day or cold since we bought the IQ Air air cleaner. Amazing. The only attack she had was when she stayed at a friends house and they lit a fire. Next day she had a mild attack.

Dylos calibrating

PostPosted: Wed Oct 15, 2008 4:27 pm
by Ernest Grolimund
Woody: Post the pm2.5 numbers from the state next to the dylos readings if you can. They are available on the DEP website. Call to get help on obtaining it.

PostPosted: Wed Oct 15, 2008 6:34 pm
by turning_blue
Thanks so much for posting this.

The conversation between you and Ernest is very helpful too. Thanks for communicating this so well. It's what I need. Keep up the great work! Great teachers here!!!

PostPosted: Thu Oct 16, 2008 1:30 am
by Wilberforce

(A) I'm not sure if activated charcoal will effectively adsorb carbon monoxide, as it is a very
small molecule. But AC will adsorb VOCs and other large-molecule poisonous gases effectively.

(B) The CO detector alarm will not go off until CO concentration reaches dangerous levels.
But chronic exposure to even low-level concentrations are still detrimental to health. If smoke
from an outdoor wood boiler is entering your house, rest assured that invisible CO is entering
the house also. CO is what gives headaches and nausea. PM causes coughing, sneezing, and
asthma attacks.

That brings up a question: what about the outdoor CO concentrations, especially in proximity
an OWB? Mount your CO detector out there and see if the effluent sets it off. If not, then there
is not a high level of danger. But the gas is still there, and cannot be ignored.

This is potentially a killer gas which should not be there at all!

What Do Carbon Monoxide Levels Mean?
"Although the automobile is to blame for most of the CO problem, chimney smoke from wood stoves
is beginning to compete with it as the most objectionable source of air pollution in some suburban
areas. In this case, it is not just the CO that matters, but other gases and particulates as well."

PostPosted: Thu Oct 16, 2008 8:29 am
by turning_blue
I am now buying a CO detector for the rooms that are so quickly filled with neighbor's chimney smoke. Thanks for mentioning this. Actually last year, when my I had a big monitor set up in our family room from a local anti-pollution group, it was picking up a lot of CO. We thought it was an error. I will post the monitor type as soon as I can. The wood stove next door was on at the time too.

Thanks again for bringing attention to this.