What safety measure should be taken with thermal fog generators?

Using thermal fog generators requires careful safety precautions, and one of the most crucial measures is to avoid turning on electric switches while fog is present. When thermal fog is generated, it creates a dense mist that can contain flammable chemicals. If any electrical equipment is activated in the presence of this fog, it could trigger a fire or an explosion due to the flammable nature of the fog's contents.

Therefore, ensuring that no electrical switches are activated during the operation of a thermal fog generator helps mitigate the risk of accidents and protects both the operator and the surrounding environment from potential hazards. This emphasizes the importance of maintaining safety protocols when using equipment that generates fog, where the presence of chemicals can significantly elevate the risk of fire and other safety hazards.

The other options do not align with safe practices: inexperienced operators often should not use complex equipment without supervision or guidance; keeping pilot lights on could create an ignition source; and allowing fog to linger increases the risk of exposure to harmful chemicals and doesn't adhere to safety standards for dispersal and area clearance.