Why do iron objects rust readily in coastal areas?
The reason that iron rusts anywhere is because oxygen and iron produce iron oxide, more commonly known as rust, in a chemical reaction. Coastal areas tend to be more humid than other areas, so there is more moisture in the air. Water is about 33% oxygen, while air is about 21% oxygen. So, air with more water has more oxygen, which makes iron rust faster. Think of it this way, if you separated 200 cubic meters of air with no water in it into separate parts, you would have 42 cubic meters of oxygen. This is a very exaggerated landlocked area. Let’s say we had another area where the air is so humid, that half the air is water. With, again, 200 cubic meters of air, there would actually be 100 cubic meters of air and 100 cubic meters of water. There would be 21 cubic meters of oxygen in the air section, and 33 cubic meters of oxygen in the water section. 21+33=54 cubic meters of oxygen in the coastal area. So, to sum up, more coastal=more humidity=more oxygen=faster rust on iron.
