It's not dangerous unless you're an infant. Even when asleep, children and adults will quickly be roused by rising CO2 concentrations. Infants are the only humans who sometimes lack the necessary mechanism. The threshold for rapid loss of consciousness or fatality is very high -- 10-20% -- and is highly unlikely to be reachable by dry ice subliming in a bedroom.

Is that likely to cause problems? CO2 burns and it requires a lot of it to displace oxygen.

What do you mean, it burns?

Well, it will stick to the ground since it is heavier than air, and it is toxic long before oxygen is displaced [1]. And dry ice contains a very large amount of gas!

[1] http://www.principia-scientific.org/at-what-concentration-do...

>What do you mean, it burns?

Discomfort. But I can't seem to find a source on what percentage is necessary. It might be higher than the suffocation percentage.

You mean, the gas? Dry ice, yes, because it is cold, but the gas? (This is the first time I heard that and I find it hard to imagine.)

I think Dylan's referring to the way elevated CO2 stings your eyes, nose, throat. Lungs too if it gets that far. It's weird sensation, and it definitely feels "hot" in a way. Asphyxiation by CO2 is quite unpleasant.

Ah, I see. That makes sense. Thanks for the clarification.

When you come into direct contact with something that cold, it causes a sensation that feels very nearly identical to being burned.

10 % concentration lets you asphyxiate, and it is heaver than air. If I remember correctly, 1 L dry ice turn to 750 L in gaseous form.

In a large, cool room and under a cover it probably is not an issue, but something to be aware of. In a small room or a car it could get critical quickly.

This is what I'm talking about: https://www.youtube.com/watch?v=YIgV2Q8Leh0

I'm sure they used at least as much for the body, which is a lot once it sublimates into gas.