When is it inappropriate to conduct non-soil fumigation?

Non-soil fumigation should not be conducted during extreme weather conditions because such conditions can significantly affect the efficacy and safety of the fumigation process. Extreme temperatures can alter the volatility and penetration of fumigants, making it difficult to achieve the desired pest control results. For instance, high temperatures may increase the evaporation of fumigants, while low temperatures might hinder their vaporization and dispersion. Additionally, strong winds can disperse fumigants away from the intended target area, leading to ineffective treatment or unsafe exposure to non-target areas.

Addressing the other options, while conducting non-soil fumigation without proper equipment can certainly lead to ineffective treatment, the question specifies "inappropriate" timings rather than operational capability. Fumigation can be performed at night when certain pests are more active, making nighttime application potentially advantageous. Lastly, conducting fumigation when treatments are not needed is more related to resource waste or unnecessary application rather than timing appropriateness, which does not fit the context of environmental conditions impacting fumigation procedures directly.