Which of the following correctly describes a flammable explosive atmosphere?

A flammable explosive atmosphere is defined by the presence of a mixture of air and flammable vapors, gases, or dust that can ignite under certain conditions. This condition occurs when the concentration of the flammable components falls within a specific range that is capable of supporting combustion or explosion if an ignition source is present. The essence of the statement is that it details the necessary components for an explosive environment.

In contrast, high levels of moisture do not inherently create a flammable explosive atmosphere; instead, moisture can sometimes dilute flammable vapors. Extreme cold typically reduces the volatility of many substances, which further mitigates the risk of creating a flammable atmosphere. Lastly, being free of contaminants is generally unrelated to the definition of a flammable atmosphere; instead, the focus is on the presence of specific flammable constituents rather than their absence. Thus, the correct description identifies the critical condition under which combustion or explosion hazards can arise.