Hello my name is XXXXX XXXXX will be my pleasure to assist you. If you are talking about a vent free kerosene heater then this are usually very clean burning as long as you are using the clear K-1 kerosene. One thing I would recommend is lighting the heater outside and putting it outside when extinguishing as this is when the make the most smell and soot. When they are hot and burning normal the are very efficient and clean.
i have jus heard that there is problems with the breathing of the fumes from the burning of kerosene and with these two i want to be safe.
Just be sure you have a carbon monoxide detector and like I said lite it outside and it will be safe even if lighting inside its still safe its just it will smell. Only when lighting and distinguishing. I have used one myself for 12 years with 2 small children under the age of 2. It was much cleaner and safer than the woodstove we used to use.
thank you so much!!!!!!