What safety measure helps prevent ignition of flammable substances?

The correct answer involves the practice of regular monitoring of temperature, which is crucial in preventing the ignition of flammable substances. Many flammable materials have specific temperature thresholds at which they can ignite, known as ignition points. By continuously monitoring the temperature within an area where these substances are present, potential overheating situations can be identified and mitigated before they lead to combustion. This proactive approach is essential in maintaining a safe environment, as it allows for the detection of conditions that might facilitate ignition, ensuring that flammable materials are kept at safe temperatures.

The other options involve practices that can actually contribute to increased risk. For instance, extensive use of open flames directly introduces a source of ignition that can easily ignite flammable substances. The use of unventilated spaces can allow for the accumulation of flammable vapors, heightening the risk of ignition. Lastly, the application of high pressure in systems that contain flammable materials can create conditions that are favorable for ignition, especially if there are leaks or if materials become unstable under pressure. Thus, regular temperature monitoring stands out as a critical safety measure in preventing ignition risks associated with flammable substances.