[Cristina]

Cristina asked the Naked Scientists:
   
Dear Dr. Chris.

Back in school, I learned that plants emit oxygen during the day and carbon dioxide at night. And that's why it's dangerous to have plants in the same room where we sleep.

So my questions are: Is this completely true? Do all kind of plants emit the same amount of carbon dioxide? Which symptoms should we feel if we are in a room with too much carbon dioxide?

I'm living in a studio (basically one big room) of 4 x 15 metres
approximately and I have 9 plants (medium to small sixes). Am I exposing myself to too much carbon dioxide at night? Should I get rid of my plants?

Can I have even more without worrying about it?

Loving your program more and more every week.

Cristina (from Spain, living in Cambridge, UK)

What do you think?

[Don_1]

Plants do use oxygen by night and 'exhale' CO₂.

However, I rather doubt you are likely to suffocate during the night.

[Bored chemist]

This idea started because, long ago, some hospitals removed the floweres from the wards at night. People thought it was due to the plants using up the O2.
Actually it was to stop people knocking them over in the dark.

To a rough aproximation you need a tree to provide enough oxygen for you to breathe. Since the tree is growing you know that it must, on average, take in more CO2 than it produces.
So the night time rate of CO2 production must be smaller than the rate of CO2 absorbtion during the day.
Since that's roughly the amount of CO2 you produce it's fair to say that, even if you had a whole tree in your room it wouldn't produce as much CO2 in the night as you do.

Keep the plants, but put them on sturdy tables soo they don't get knocked over, and sleep well.
Unless they are trifids :-)