Certified Apartment Maintenance Technician (CAMT) Practice Exam

The correct answer is carbon monoxide. Carbon monoxide (CO) is a colorless, odorless gas that can be produced when fossil fuels, like natural gas, are incompletely burned in gas heating systems. This makes it highly dangerous, as it can lead to poisoning in enclosed spaces where ventilation may be insufficient.

The risk of carbon monoxide buildup is particularly significant in residential settings, where malfunctioning heating systems, blocked exhaust vents, or improper installation can increase the likelihood of CO accumulation. Symptoms of carbon monoxide poisoning include headaches, dizziness, confusion, and can be fatal if exposure is prolonged without adequate oxygen.

While ozone can be a concern in certain environments and is associated with electrical devices and high-voltage equipment, it is not a primary byproduct of gas heating systems. Carbon dioxide is a naturally occurring byproduct of combustion but is less hazardous compared to carbon monoxide since it is non-toxic at normal levels and does not cause poisoning in the same way. Nitrogen dioxide, also a byproduct of combustion, can contribute to respiratory issues, but it is not as immediate a danger as carbon monoxide in gas heating systems.