What type of tools should not be operated in flammable atmosphere environments?

When operating in flammable atmosphere environments, it's crucial to minimize the risk of igniting combustible materials, which is why power tools should be avoided. Power tools can generate sparks, heat, or even static electricity as they operate, all of which pose a significant fire hazard in areas where flammable gases or vapors are present.

In contrast, manual hand tools typically do not create sparks and are generally safer for use in these sensitive environments. Pneumatic tools, while they can also pose risks, may be specifically designed to be spark-free or have features that reduce spark generation, such as using non-sparking materials. Emergency tools can vary greatly in design, but they can also be made for safe use in flammable areas. Thus, the risk associated with power tools makes them the least appropriate choice in flammable atmospheres.