Which of the following is a safety hazard associated with gas heating systems?

The presence of carbon monoxide buildup is a significant safety hazard associated with gas heating systems because carbon monoxide (CO) is a colorless, odorless gas that can be produced during the incomplete combustion of fossil fuels, including natural gas and propane. When gas appliances are not functioning correctly or when ventilation is inadequate, carbon monoxide can accumulate in a space, leading to serious health risks or even fatalities. Symptoms of carbon monoxide poisoning can include headaches, dizziness, confusion, and, in severe cases, loss of consciousness and death. Therefore, proper installation, maintenance, and regular inspection of gas heating systems are critical in preventing carbon monoxide buildup and ensuring user safety.

In contrast, low humidity levels, exposure to ultraviolet light, and high energy consumption do not directly relate to the safety hazards posed by gas heating systems in the same manner. While they may present some discomfort or inefficiency, they do not carry the acute life-threatening risks that carbon monoxide accumulation does.