Which statement correctly describes the behavior of carbon monoxide after a fire has been extinguished?

Which statement correctly describes the behavior of carbon monoxide after a fire has been extinguished?

• A. It remains at toxic levels indefinitely.
• B. It is immediately cleared by ventilation.
• C. It decays rapidly to zero within seconds.
• D. It dissipates over time after removal from the fire environment.

Answer: (D)

Carbon monoxide does not spontaneously disappear or decay rapidly after a fire. It behaves as a gas whose concentration falls primarily through dilution and ventilation. Once the fire is controlled and the space is ventilated or opened to fresh air, CO gradually dissipates as the contaminated air is replaced. It can linger in enclosed areas or within pockets of debris, but over time these concentrations decline with air exchange. So the best description is that CO dissipates over time after removal from the fire environment.

Carbon monoxide does not spontaneously disappear or decay rapidly after a fire. It behaves as a gas whose concentration falls primarily through dilution and ventilation. Once the fire is controlled and the space is ventilated or opened to fresh air, CO gradually dissipates as the contaminated air is replaced. It can linger in enclosed areas or within pockets of debris, but over time these concentrations decline with air exchange. So the best description is that CO dissipates over time after removal from the fire environment.