No. That is not a concern on any kind of level. Quick look indicates asphyxiation at 16-21%. At 5-15% concentration it is explosive. Current levels are about 2

No. That is not a concern on any kind of level. Quick look indicates asphyxiation at 16-21%. At 5-15% concentration it is explosive. Current levels are about 2000 parts per billion. It will not release that quickly on anything more than a localized level, and it would probably kill you via explosion, first. Since it would be gradually released we would all be long dead from the greenhouse effect.