re:12-Sep-97 Will sleeping in a closed room with an electric fan cause death?

Cecil's Columns/Staff Reports
1

Just how long CAN a person stay alive in a closed bedroom before being overcome by CO2 (that’s carbonDIoxide, the stuff we exhale)?
Cecil dismissed just plain running out of air, but I don’t think so.I’m guessing 24 hours. I often feel I’m suffocating when I wake up.

Anyone able to help with the calculations?

Please stick to these Assumptions:
1)The room is small like mine (8’x8’x8’)
2)and nearly airtight (masonry-walled brownstone basement room with the casement window long painted shut)
3)Don’t change the problem by adding gas leaks or radon. The question is NOT why I can’t breath, but whether lack of air alone COULD be the problem.

I got partial numbers relating to the problem, but can’t do the math. Unlike the Assumptions, if you have better numbers I’d like to know them.

4)I read that a person lying in bed consumes eight quarts of air per minute.
5)(From the EPA website) 3 percent CO2 will put you in a coma.
6)Since the air starts off at 0.5 percent CO2 and 20 percent O2, you only have to use up (convert by breathing) 1/8 of the oxygen before you are overcome by CO2.

I.e., you would run out of air 8 times faster than you would guess from oxygen usage calculations alone.

Now, how long is that exactly? (If the answer is less than 24 hours, we should get Cecil to reconsider.)

2

Please post a link to the column you’re referring to. Don’t just wait for Arnold to do it.

  • Jill
3

I don’t know how to post a link. I suppose that makes me stupid, but I’m not good with computers.
The column under discussion is the one in the Topic: re:12-Sep-97 Will sleeping in a closed room with an electric fan cause death?

4

http://www.straightdope.com/columns/970912.html

5

Don’t ever say that, Lamerino. Stupidity is incurable. Ignorance is not, as I see you have discovered.

Welcome to the board!

Your brain-in-a-jar,
Myron

Imbibo, ergo sum.

6

It sounds like you might be mixing up carbon monoxide and carbon dioxide. I wasn’t aware that carbon dioxide was harmful - I thought you could breathe air that was 80% CO2 as long as 20% was O2.

CO is another story - it robs your blood cells of their oxygen.

7

NO. NOT CO. That stuff is worse. Doesn’t everyone know that?
CO2, the stuff you exhale, is what is in question here.

This is what the EPA site said:
"We have
general information on the topic some of which I have noted below. All of
our information can be accessed via our website at www.epa.gov/iaq/pubs

Carbon dioxide can be used as a rough indicator of general ventilation
quality when related to the number of occupants within the building or space.
One of the by products of human respiration is carbon dioxide gas. If a
building is occupied with a normal number of people, and it is properly
ventilated, the carbon dioxide level will typically not exceed 1000 parts per
million (ppm) at its highest point during the day. If the level is higher
than 1000 ppm, either the outdoor air supply rate is too low, or there are
more people in the building than the building was designed to handle.
Examples of average occupant densities for office building is 7 persons for
each 1000 square feet of floor space, 30 persons per 1000 in schools, and
four people in homes. (NOTE: carbon dioxide levels that are less than 1000
ppm do not insure that indoor air quality is good. Carbon dioxide
directly relates to human respiration, and not to other pollutants that may
be present). However, with levels exceeding 1000 ppm which may indicate poor
ventilation, pollutants from other sources may accumulate.

Human health effects directly related to carbon dioxide exposure include
increased respiration rates and breathing difficulty at levels above 15,000
ppm; headaches, dizziness, and nausea at levels above 30,000 ppm; and stupor
and death at levels between 60,000-80,000ppm. "

8

Well, let’s take a look at lamerino’s numbers and do a BOTEC.

OK, by definition, that’s 512 cubic feet = 35.3 cubic meters (I’m going to do a lot of these calculations in metric because I’m more comfortable with that).

Now, of course, the room is not empty by definition – it contains at least lamerino, and probably some furniture, too. I will assume that 90% of the total volume is air space.

That’s probably not airtight – you’d be surprised how many small leaks there can be and how they can add up – but, since that makes the calculations easier, I’ll buy it provisionally.

I don’t have numbers for or against these statements at my fingertips, so again, I will accept them provisionally.

Eight quarts/minute is, FTR, 0.0076 cubic meter/minute.

The air in theseparts starts off at about 0.03% CO2; possibly you should look at the overall air quality of your housing. I will agree, however, that 0.47% probably doesn’t make much of an absolute difference.

Now, the room contains about 31.77 cubic meters of air (volume of room - volume taken up by other objects). Our hypothetical sleeper breathes 0.0076 cubic meter/minute of that air. A crude calculation of 31.77/.0076 gives 4180 minutes = 69.6 hours. Unless the sleeper is already comatose, there’s plenty of air in the room.

But wait, there’s more! The air starts out with a negligible carbon dioxide content (0.5%, 0.03%, whatever), whilst, after it has been used by the sleeper, it is nearly 3% CO2 (breathing is regulated by the CO2 content of air, not by the O2 content; otherwise, deaths by hypoxia would be less common). We assume that the 0.0076 cubic meter/minute figure for sleeping air consumption is for good-quality air, and, as the CO2 concentration goes up, the rate of breathing also goes up. Thus, the amount of air consumed is essentially the integral of function of decreasing air quality over time.

Now, I’m a calculus whore (I only do it for money, and then the results aren’t satisfactory to anyone). A crude calculation suggests, however, that the doubling time for CO2 concentration in bad air is about 580 minutes. Even assuming that the air starts off 0.5% CO2, our sleeper ought to have 1039 minutes = 17.32 hours before he reaches the point where he never wakes up again.

Incidentally, the original column was on whether an electric fan somehow added to or subtracted from the air something that contibuted to asphyxiation. The evidence is that that electric fan might actually extend our guinea pig’s lifespan by stirring up the “dead”, air.

“I don’t just want you to feel envy. I want you to suffer, I want you to bleed, I want you to die a little bit each day. And I want you to thank me for it.” – What “Let’s just be friends” really means

9

in reply to the question about how long a person can live in a closed off room. here are a few facts that will mess with you some more :). if the windows have been long painted shut it’s probably an old house, therefore not airtight,also heaters are often kept in the basement, meaning ductwork coming down( and giving a way for fresh air.) a heater would not work without fresh air the same as you wouldn’t. third you say a person may consume 8 quarts of air an hour. is this the amt of CO2 a person produces or just the amt of air a person breathes, because not all the air you breathe in comes out as co2, this is why cpr works, plus how much of a gap is under the door to the basement? I think you could stay down there indefinitely and have nothing to worry about.

10

Now, see, that’s why I asked you not to change the assumptions. No, I don’t have heat ducts, but an electric space heater. (The old coal boiler was removed decades ago and holes plastered over.) The age of a brownstone basement doesn’t affect it’s airflow, as it is stone and below ground. There’s no gap under the door, since the floor and hall have wall-to-wall carpet, also decades old.

The 8 quart number I got out of a syndicated newspaper feature called “Our Fascinating Earth/Phil & Nancy Seff”. Not a great source, but I did say I’m open to better numbers.
Since Akatsukami (reader above)(thanks Akatsukami, this was the analysis I was looking for) said 17.32 hours, I have cause for concern. When sick I think nothing of such time spent without leaving the room.
As to the fan, Cecil said it didn’t probably matter, which is true. But then he still analyzed the deaths for simple running out of air, as this discussion does.

11 
 Your respiration rate will have *VERY* little effect on the rate at which you use up oxygen. (It will have a slight effect as your body is working slightly harder, thus using slightly more.)

 Multiply that .0076m^3/min figure by the 20% initial O2 concentration, you are using .00152m^3/min of oxygen. The original room had 35.3m^3 of air = 7.06m^3 of oxygen. The danger point is when 15% (3%/20%) is converted to CO2. It will be exhausted in 77 hours, the danger point in only 11.6 hours, or if we accept his high initial CO2, 9.6 hours.
 Your math is the time to total exhaustion, not to 3% CO2.
12

Ran across this info from ASHRAE
American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE

ASHRAE Standard 62-l989, Ventilation for Acceptable Indoor Air Quality, specifies the
outdoor air ventilation requirements
at a minimum of 15 cfm per person in non-smoking areas, regardless of occupant usage

This means there should be enough fresh air introduced to completely
renew the air in the house roughly every three hours.

every home has individual factors which affect indoor air quality. These range from the
number
of occupants and their personal habits, to pets, furniture, carpeting and cleaning
products. The effects of long term human
exposure to a number of indoor air pollutants are yet unclear; human tolerance levels
of certain chemicals also vary.
Efforts to determine various “safe” levels of indoor air pollutants are being carried out
by a number of organizations

I suggest that you crack the door and put your fan in front of it.

13

Where and what kind of bed is it? Is it just a matress on the floor, or do you sleep on the top bunk? CO2 is heavier than normal air, so if you sleep on a mattress on the floor you might not last quite as long as you would on an elevated bed.

my $.02
 Morkster

Legal Notice: Receipt of this message constitutes your unconditional acceptance of agreement with all terms, conditions, conclusions and opinions, either expressed or implied, as interpreted by the author without further clarification. Use of any information contained herein [inclusive of any and all attachments] or omitted in part or in whole from the actual message is strictly prohibited and will be subject to collection of significant financial damages.

14

The top of the bed is 20" from the floor. It’s about 3" from any wall. Has legs, not a drawer or anything underneath. No headboard. 200 count sheets, non-allergic blanket and low pillow. My nose is about 20-26" from the floor, depending how I roll at night.

(2 cents buys a lot in my neighborhood :))

P.S. I think the fan, like all motors, produces poisonous ozone. Korean fans are the worst.(Except at soccer matches, where Aussie fans kick butt.)

15

Close enough. The bed has a dust ruffle- if that makes a difference I will be glad to remove it so the calculators out there won’t get distracted.

Also, I’m perfectly average height, weight, health, lung capacity, and paid up on my rent so the landlord won’t knock and let it hall air.(Which is probably as bad as mine, anyway.)

No TV, fridge, hot plate or curling iron to change the atmosphere in any way.

I am continent but use a bedpan and chamberpot anyway to avoid climbing stairs to the loo at night. What else? Have a note on the door: “Do not knock day sleeper-leave packages with neighbor.”

Can’t think of it now…getting woozy…must find Toto…

16

Some people agree with you at this thread:
http://boards.straightdope.com/ubb/Forum1/HTML/000634.html