Which type of hazardous materials requires immediate evacuation of the area?

The requirement for immediate evacuation of an area is primarily associated with hazardous materials that are highly toxic or pose an explosive risk. Highly toxic substances can cause serious health impacts or fatalities upon exposure, even in small amounts. The rapid onset of effects from these materials necessitates quick action to protect public health and safety. Additionally, materials that present an explosive risk can lead to catastrophic events if not handled properly, posing immediate threats to life, infrastructure, and the environment.

In contrast, materials that are environmentally friendly, non-toxic, or harmless do not pose such immediate dangers to individuals in the vicinity, thus evacuation is not warranted. Similarly, materials characterized by low volatility typically do not evaporate quickly or pose instant risks, further reducing the need for urgent evacuation. Therefore, considering the potential threats from toxic or explosive materials emphasizes the need for immediate action to ensure safety in hazardous environments.