What is back-drafting?

Back-drafting refers to a condition where combustion products, such as carbon monoxide or other fumes, are drawn back into the living spaces of a house instead of being safely vented outdoors. This often occurs due to negative air pressure in a building, which can be caused by various factors, including malfunctioning exhaust systems or inadequate makeup air for combustion appliances.

Understanding back-drafting is crucial for building safety and indoor air quality, especially in homes where gas appliances are used. If back-drafting happens, it can pose significant health risks to occupants due to the inhalation of harmful gases.

The other options describe different concepts: increasing indoor air pressure relates to ventilation strategies but does not define back-drafting; normalization of indoor radon levels pertains specifically to radon mitigation rather than general air quality; and sealing vent systems, while possibly related to airflow issues, does not directly align with the phenomenon of back-drafting. Recognizing the significance of back-drafting aids in ensuring safe indoor environments, particularly in buildings with combustion appliances.