[olau]

Is suspect you can search for this, but here's a quick shot - how much living material is inside them? Let's say all the plants weight the same as one human. And they don't need to keep warm. So most likely they're not respirating more than one extra human. And I don't think having three people in a bed is unsafe.

[Timucin]

I just had a chance to do a bit research and read about the facts and I believe you're right.

It seems even a small pet, like a hamster, could produce more CO2 than a home full of trees/plants during the night.