Which of the following is NOT a characteristic of carbon monoxide?

Carbon monoxide is characterized as a colorless, odorless gas that is produced most commonly from the incomplete combustion of fossil fuels, such as gas, oil, coal, or wood. It can accumulate in spaces where burning occurs, particularly in poorly ventilated areas, leading to potentially dangerous levels that pose serious health risks. The fact that carbon monoxide is odorless is critical for understanding why it is often referred to as a silent killer; people may not realize they are being exposed to it, making awareness and detection paramount in indoor environments.

The notion that carbon monoxide has a noticeable smell is incorrect, as this characteristic can lead to misunderstanding and potential danger. It is important to note that other gases, such as natural gas, do have distinct odors added to help alert individuals of their presence, while carbon monoxide does not share this property. Thus, identifying carbon monoxide's attributes, including its lack of smell, helps promote safer practices regarding the use of combustion appliances and the importance of proper ventilation in living and working spaces.