Final answer:
During a fire, vaporized oils carried by smoke settle as a difficult-to-remove 'oily residue'. This residue is similar to greasy soot seen in industrial settings or from environmental events like oil spills, posing cleanup challenges and environmental impacts.
Step-by-step explanation:
During a fire, smoke can carry vaporized oils, which eventually settle to leave an oily residue on surfaces, which is difficult to remove. This residue represents some of the challenges associated with fires beyond immediate damage, as cleanup and restoration can be extensive due to the greasy soot that must be removed from various surfaces. Not only does this impact human-made structures, but the environmental impact, similar to an oil spill on water, can be significant and long-lasting, affecting ecosystems and wildlife.