Where is soil-to-air corrosion typically most severe?

Soil-to-air corrosion typically occurs in a transitional zone from above the ground to just below the surface, which is why the area from ground level to several inches below ground level experiences the most severe conditions. This zone is where moisture, oxygen, and other corrosive elements can come into contact with the metal structure, promoting oxidation and degradation.

The combination of atmospheric and soil conditions creates an environment that is highly conducive to corrosion. Above ground level, the exposure to air may limit moisture retention but can be affected by environmental factors such as rain and humidity. Below ground level, corrosion mechanisms differ, with microorganisms and electrolytic solutions in the soil contributing to corrosion, but the interaction with air diminishes.

Thus, the most severe soil-to-air corrosion typically occurs right around ground level, where the metal structures are simultaneously exposed to both the soil and the atmosphere, leading to compounded corrosion effects.