We proudly advertise that FLÎKR Fire will not produce carbon monoxide or put soot into your home. while this is true we want to clarify a few things. While some fuels produce carbon monoxide as a by-product of burning, isopropyl alcohol does not. However, in the absence of enough oxygen, ANY fuel (even a cigarette lighter) can begin to produce carbon monoxide and soot. This can occur for various reasons but most often in a tightly sealed space (which often contains an air exchanger). knowing this we have always said thatFLÎKR Fire must only be burned in a well-ventilated room; by, “well-ventilated” we mean the active exchange of air (thereby oxygen). However, the moreFLÎKR Fire gets out into the world (yay!) the more we realize the need to further educate both our sellers and buyers. Unfortunately, given the possible variations in a home, There is no single standard or test by which we can guarantee plentiful oxygen. So as a refinement of our statement about being, “well- ventilated” we now say thatFLÎKR Fire should not be burned in a room smaller than 300 ft2. To especially ensure soot does not appear around your home no other flames should be lit and a window must be cracked in the roomFLÎKR Fire is burning. Also regularly wipe out the burn chamber. If soot appears anywhere other than where flame touches stop usingFLÎKR Fire indoors as this can signal a lack of oxygen in your environment. With tens of thousands of units sold, we have had .0001% of customers report a problem with soot. ButFLÎKR Fire is more than a business to us and we are driven to get the number of issues to absolute zero. we continue to sell with confidence in our product while we are excited to keep problem-solving with any and all customers.