The use of fans to distribute the air in a closed area ___ sufficient to avoid toxic concentrations of carbon monoxide.

• A. is not
• B. is
• C. may be
• D. could be

Answer: (A)

Distributing air with fans only circulates the same air and any carbon monoxide already present; it does not remove or dilute the contaminant. To keep CO concentrations from becoming toxic, you must remove the gas from the space or dilute it with outdoor air through proper ventilation. Fans can help with air movement, but without exhaust paths and make-up ventilation (or eliminating the CO source), the concentration can remain high or even spread to other areas. That’s why relying on fan circulation alone is not sufficient to avoid toxic CO levels.