While generally safe, the primary threat posed by gas heaters is carbon monoxide poisoning, although the combustion process produces less carbon monoxide than the combustion of wood or coal. The design of these heaters and warning systems provide some protection.
Most ventilated gas heaters require sufficient ventilation to ensure proper combustion, and most shut off if airflow is insufficient. In addition, regulations often require systems to have built-in oxygen sensors to determine if improper ventilation is causing potential safety hazards. Still, experts advise regularly examining ventilation systems to ensure they are free of obstructions, as safety systems can malfunction and pose a risk to occupants.