Plants in hospitals

Tony Travis ajt at
Wed Oct 21 17:43:48 EST 1992

In article <921021161238.MIN-LJTBa00256.bionet-news at> you wrote:
: Okay... here's a question which I got from a student who stopped by my office 
: this morning.  According to the student, one of my colleagues stated in lecture
: that some hospitals prohibit house plants in patients' rooms in order to 
: prevent a loss of oxygen during the evening when they respire.  While I 
: found this statement rather ludicrous myself, I could see a hospital 
: official making this kind of statement in order to limit houseplants for some
: other reason (the mess they make, or perhaps the fact that nobody takes care
: of them and they have to be thrown out later on).  

Humans are, in fact, more sensitive to increased CO2 than decreased O2
in the air they breathe and since plants respire they contribute to the
increase in CO2 concentration in a room at night when they are not
fixing CO2 by photosynthesis.

However, as I pointed out in response to a question a while ago I find
it difficult to believe that a few plants can produce enough CO2 to
significantly change the level of CO2 in the volume of air contained in
an average hospital ward overnight in comparison to the CO2 produced by
the patients.

The rate of exchange of air in the ward with air outside (or the
ventillation system) is likely to be such that it would be almost
impossible to detect an increase produced by plants in the room.

Anyone who has tried to measure rates of CO2 fixation in even a small
growth chamber will tell you how sensitive the IRGA has to be to detect
any change in CO2 level.  Maybe you should set up a student project to
actually monitor the CO2 level in a hospital ward with or without
plants and shut the administrators up once an for all :->

Dr. A.J.Travis,                       |  Tony Travis
Rowett Research Institute,            |  JANET: <ajt at>
Greenburn Road, Bucksburn,            |  other: <ajt at>
Aberdeen, AB2 9SB. UK.                |  phone: 0224-712751

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