Artificial odors, including sausages, cheese, dog treats, and so forth.
2. Soil damage caused by walking, kicking, shuffling, and so on. Walking causes physical
changes to the surface and brings out odors of plants (e.g., plant sap from crushing the
plant, and subsequently bacteria growing on damaged areas of plants).
3. Odors of footwear (which vary according to the components of the shoe, such as rubber,
leather, cloth, etc.), including shoe polish and items ground into the soles.
4. Individual human odor, as discussed earlier (including secretions of different glands and
microbes present on human skin), and foot sweat