Which factor does NOT affect the risk level of a hazardous substance?

The time of day when an incident occurs does not directly influence the inherent risk level of a hazardous substance. While the time may have implications for factors such as emergency response capabilities, visibility, or population density, these factors do not alter the chemical or physical properties of the hazardous material itself.

In contrast, the volume of the material influences the potential for exposure and the severity of the incident—the more material that is present, the greater the potential impact. The properties of the hazardous material, including its toxicity, reactivity, and persistence in the environment, are critical for assessing risk. Weather conditions during a spill, such as wind direction and temperature, can also significantly affect how a hazardous material disperses and poses a threat to people and the environment. Therefore, the time of day is not a determining factor for the risk level of a substance itself.