If its like 1920 to earlier, yeah it could be that the pipes have corroded too much on the inside.You can usually tell copper vs steel by scraping the pipes with a hard object to see if its copper or steel under the oxidization.   

The BIG factor is making sure the product has a better scratch resistant FINISH over the wearlayer, preferably aluminum oxide or a ceramic bead and two coats if possible.

If you have curtains throw them in the wash.Whatever is left, ozone (O3, made from O2) will oxidize it, one molecule at a time.

Ozone works on odors that can be oxidized like smoke and mildewy type smells, but urea cannot be oxidized the same way.

Also make sure you have a scratch resistant FINISH, Aluminium Oxide, Ceramic bead etc.

I’ve not used these myself for metal roof projects yet, but can report good things from this brand.https://www.lowes.com/pd/Teks-9-x-1-1-2-in-Zinc-Pl...The ones with small washers tend to be used for metal applications and the ones with large washers for spreading the load across surface area (probably ideal for translucent material of a greenhouse).As others have mentioned, the key is to have a decent coating that resists oxidation and a good seal.If these are used for penetrating metal, It’s sometimes helpful to give the screw a light tap with a hammer to keep the screw from wandering, potentially scratching or denting the roof when the driver gets wobbly.

I have bought one years ago and we use it to get rid of smells and odors, it oxidizes everything organic, BTW that includes mold and mildew.The smell originates probably also from the padding, that will be tough to get ridg of.

Wood floors are soft and scratch easily and would require refinishing with every new tenant where a better quality LVT with at least 12 mil wearlayer AND  A SCRATCH RESISTANT  FINISH like Aluminum Oxide or one of the newer Ceramic Finishes will last longer.

It was near an old dryer vent so probably absorbed ambient moisture or it could have been a leak near the entrance of the feed through the wall.When I install new breakers &/or a new panel I apply Ox-Gard Anti-Oxidant.

Sorry for that big, orange, nitrous oxide cloud a couple years back, by the way.Always open to new ideas!