Date: Sunday, October 27, 2002
please explain to my son on an elementary level, how the
oxygen is replenished in our homes/cars if we keep all the windows
closed for extended time periods (Oct- Mar-winter in Ny) He's worried
that we may not be getting enough air in the house, especially if we are
all breathing it in. Please respond as he is nervous about this and we
have to keep our windows open until we get a response.
A very interesting question.
I don't have an answer from any particular research,
but I will tell you my understanding of this matter.
Your son has a very good point. During the time homes
are closed up (for example, wintertime), air quality
can reach unhealthful levels.
We rely during the summer for open windows and the
occasional open door to allow some venting of the air
in the house out to the environment, and replenishment
with 'fresh' air.
There are many materials which can contribute to the
unhealthful air I mentioned above. Some are:
smoke from smoking and cooking
volatile components of dyes from carpeting and
fabrics, and of finishes on furniture ond floor
"dirt" stirred up by walking inside the house of
materials deposited on carpeting including residues of
herbicides, pesticides, salts, etc.
volatile residue of cleaning material, for example,
remaining small amounts of dry cleaning materials on
clothing, drapes, etc.
volatile compounds from the combustion of heating
natural chemical releases from the earth which enter
the home via cellar floor cracks, eg. radon
To the extent a house is tightly buttoned-up, the conc
entrations of these materials can reach levels where
irritation can be caused to human mucous membranes.
Any amount of venting of home air to dissipate such
materials can have immediate effects in diminishing
the unhealthy components of interior air.
Having mentioned all these possible sources of
materials which could make house air unhealthy, we
should remember that the oxygen we need for survival
in home air is only a minor component of the air we
breathe. Oxygen levels can be substantially reduced
in an air sample before our bodies would perceive a
One should not become paralyzed into fearing for their
'air health'; HEPA filters are available which can
reduce airborne contaminants substantially. As your
son mentions, the easiest method is to 'air out' the
house with fresh air to get rid of pigments, dyes, and
other "air pollution". Personal, I never wear shoes
in the house, so no contaminants enter the home as
residues of pesticides or herbicide or even plant
While the safety of some of the contaminants has been
established, other contaminants have not been
evaluated. This is an open field awaiting research
which could have great influence in establishing home
planning methods which insure the venting of
contaminants and replacement with fresh air. Perhaps
your son will one day want to do a scientific study of
Thanks for using NEWTON!
My first thought is to tell your son that there have been no reports
deaths due to this problem among the millions of homes in the world.
That seems to tell me we are safe even with all the doors and windows
Beyond that, even well built homes have an interchange of air with the
outside - Every time you open the door... feel the draft that likely
comes in around even closed windows... notice the draft around
If we were to live in a non-permeable plastic bag, your son's concern
would be real, but that is not the case. You have likely noticed the
notes on plastic bags - "this is not a toy" and "a suffocation hazard."
But if you look at what they "rap" the new homes in, it is described as
a vapor barrier. It stops moisture from going through, but allows air
Tell you son to breath easy.
There is little need for concern that oxygen will be depleted. First,
even a single room contains a LOT MORE OXYGEN than anyone would need for
respiration. Second, even though the windows and doors are closed,
houses exchange a lot of air with the outside unless it is sealed. This
is further increased every time someone comes in or out of the house.
Only in very confined spaces such as an empty refrigerator, does one
have to be concerned with a lack of adequate oxygen for respiration.
Some modern structures have been make "air tight" but even in these
cases it is the volatile chemicals that diffuse out of carpets and
furnishings that are of more concern than a lack of oxygen.
Although, for purposes of energy conservation, homes are increasingly
built to minimize air infiltration, there is virtually no chance that
the home in which you live is air-tight. Fresh air leaks in, like it or
not. Every time you enter and leave, air inside is exchanged with and
replenished by air from outside. The heating system causes air-flows
that contribute to the inside/outside exchange. Range hoods and attic
fans (even when not operating) are paths through which air may enter and
leave. Drafts near windows and doors can be evidence of air exchange. He
need not worry, his (your) home undoubtedly has sufficient air exchange.
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Update: June 2012