Yoga involves the practice of paying attention to your breathing. Parhaps you can get the manufacturers of these devices to spend a lot of time in their office breathing in the 'environmentally friendly' products of combustion from the gel. Certainly, closing up your windows with masking tape and plastic sheets will enhance the benefits of this combustion product.
For myself, I will install a burner that takes the air from the outside and sends the products of combustion outside to permit the neighborhood to enjoy the products of combustion.
The amount of heat produced from the gel pot is minimal, really meant as a decoration. This cosmetic fireplace can be replaced by an electric fireplace that looks as good, provides more heat, and has no products of combustion.