If you sit around a camp fire for even a few minutes your clothes are done. I just made some lox bagels and the onion odor easily washed off my hands but not the smokey smell. Doesn’t smell like fish, just smoke. And of course, smoke penetrates to the interior of hams.
Can it be that our noses have evolved to notice even slight bits of smoke, because of the potential hazard posed by fire?
I like the idea that we have evolved around fire, though not because it’s a hazard, but because it’s an ancient tool of warmth and light and safety from big predators. However, I don’t think that’s what’s going on.
Smoke is an aerosol, an air suspension of fine particles. The particles are some mix of liquids and solids. They condense on surfaces so that the surfaces how have a coating of those liquids and solids, which may take quite a long time to completely evaporate to the point of nothing volatile (and therefore nothing to smell).
Think of how yellow the walls and curtains get in the room of a smoker.
Lots of strong smells, like onion, are just gasses, and they diffuse away pretty quickly. Wood smoke contains gasses you can smell, and also particles that can continue to emit those gasses.
Smoke seems to have some kind of oily component that lasts and lasts.
Same as the odor from restaurants that deep-fat fry with bad exhaust fans when you leave and your hair and clothes reek of old French fry grease.
After I had a roommate who fried a lot of food, my kitchen ceiling had to be scrubbed clean of the yellowed oily residue.
We are just entering our season for bushfires, which has been preceded by months of occasional controlled burning, so I’ve had plenty of recent experience in smelling ambient smoke. While it can persist for 2-3 days, it will pretty much disappear if there is a shower of rain (although areas actually burnt retain a distinctive odour). That suggests to me that fine smelly smoke particles are being washed out of the atmosphere by the rain. Areas protected from rain do hang on to their smoky smell notably longer.
This is it. Smoke doesn’t simply wash off with water. As for ham, smoke dissolve into the fat, not so much into the meat.
Although a lot of the volume of wood and plant material smoke is soot (essentially, carbon), the most reactive components are polycyclic aromatic hydrocarbons (PAHs), which as the name suggests are “smelly”. PAHs are very sticky because they are essentially liquified resin (or colloquially, ‘tar’) that acts like a varnish, sticking to everything it contacts, and are very complicated hydrocarbons that are readily oxidized and break down, which results in constantly releasing volatile organic compounds, particularly benzene. When these substances attach to textiles like cotton or wool, they essentially permanently bond to the fibers and cannot just be washed or aired out, although some solvents or enzymes can cause them to break down enough that they no longer emit volatiles in volume. Many of these PAHs and their organic volatiles are metabolites that are readily absorbed by living (or recently living) tissues—hence, the smoking of meat or dried vegetables—and can be mildly toxic and/or carcinogenic with regular exposure.
Stranger
I can’t tell you why it is persistent, but I can tell you that there is a whole set of specialized tools to deal with it. Fire and smoke remediation is a big part of the Restoration industry. Oxidation will eventually neutralize most odour causing molecules, but it takes a long time.
There is a special caustic firewash product for painted walls. It will damage other finishes, so it is only used on wall paint. Significant smoke damaged surfaces may need to be sealed with ‘smoke seal’ / shellac. For structural elements that are not severe enough to be, or can’t be replaced, we will scour them with dry ice or soda blasting and then seal them. Soft goods and anything with lots of surface area is often written off.
General room odour is treated with high volume air exchange and hydroxyl or ozone generators. Both of these produce oxidizing free radicals and work very well.