What happens if a person with wounds on their hands grabs a rusty fence?
The underlying problem is the danger of tetanus. But tetanus cannot be caught from rust. The tetanus bacillus lives in the intestines of herbivores, such as horses. It produces spores, which are very resistant to the external environment. For example, they can withstand boiling water. This is why surgical equipment must be autoclaved at 134 degrees Celsius.
The spores, which are produced in their millions, remain there, waiting for conditions to return to their normal vegetative form. Hence the risk of materials that have been exposed to airborne dust for a long time. A rusty material has been exposed for a long time.
But tetanus spores do not thrive in just any wound. They are exclusively anaerobic and do not multiply in the presence of oxygen. They need a wound with dead tissue, where blood and therefore oxygen cannot reach. There they multiply and produce a tetanus toxin that causes uncontrollable muscle contractions. The patient dies when he or she is unable to relax his or her respiratory muscles.