What is the characteristic of carbon dioxide (CO2) that impacts human safety?

The characteristic of carbon dioxide (CO2) that significantly impacts human safety is that it depletes oxygen. In enclosed or poorly ventilated spaces, an increase in carbon dioxide levels can lead to a decrease in available oxygen for breathing. This can result in symptoms such as shortness of breath, dizziness, and in severe cases, loss of consciousness or suffocation. As CO2 accumulates, it can displace oxygen in the air, creating a hazardous environment for individuals exposed to high concentrations of this gas.

While carbon dioxide has other notable characteristics, such as being a greenhouse gas or lacking odor, these traits are not directly linked to immediate safety risks in the way that oxygen depletion is. Therefore, understanding CO2's property of depleting oxygen is crucial for assessing potential risks related to human safety in various environments.