Well I checked the setup at 8am (20 m inutes ago) and the temperature inside 19.5C, outside 8C! with 74% humidity which is tolerable.
I have left ventilation to allow fresh air to come in one end where my fan is and it pushes the air to the other end of the GH and it leaves via a ventilation hole there. so I don't think there are any nasties left behind.
I
am using propane gas in a BBQ cylinder.