Smell is the keying of chemical compounds by receptors captured in our nose and transmitting a signal of the presence of these compounds to the brain. We have evolved these receptors to determine the presence of specific chemicals to ensure health and wellbeing, but we can now use the receptors for enjoyment and understanding, beyond the physical requirement to sense dangerous materials and compounds.
Scent works at distance like vision and hearing, but scent has another dimension, in that simpler compounds seem to last longer in the environment to be experienced than more complex compounds, which deteriorate quickly. Most scents are complicated and have multiple compounds, and the proportion of these creates a signature smell, so two materials may have similar chemicals, but one has one more than the other, then the smell will be different, if the human nose can recognize the compounds. We are able to smell many thousands of chemicals, but other species can sense more, so it is understandable that some animals will have a better or different understanding of the elements in the environment than we do. Nevertheless, scent is an extremely important sense that transmits information, but it is commonly overlooked for first, vision, and second hearing.
Through evolution, we have developed the sense of smell to detect materials, however we can now use the sense to convey information, as well as receive such. We are able to create and capture smells through perfumes, essential oils, reduction, and other methods. These can be used for specific knowledge, especially along cultural lines. Some groups have special meaning associated with certain smells, and this knowledge allows us to use these smells as signals or warnings.
Because of the bias toward vision and even hearing, we do not often think of using smell in design except perhaps cooking. However, as architects, we should. Scents and memories are very closely related. When we smell, we sniff the scents through our noses. In our nasal cavities, we have chemical receptors called the olfactory receptor cells that transfers the smell from your nose to the brain through the olfactory bulb which is responsible for analyzing smells in the brain. Due to the closeness of the olfactory bulb with the amygdala and hippocampus (the regions of the brain responsible for retaining memories), many smells overlap with memories, and memories can be easily triggered with a specific smell.
There are cultural aspects to utilizing smells in interior design, as well. For every different city and region, there are universal smells that the area is accustomed to, and there are many different smells that the area or community has never grown fond of. Knowing each community is essential to create living spaces that will be liked. For example, a person from Chicago, Illinois may be accustomed to the smell of their environment and genuinely enjoy the aroma of the streets, but a tourist from Atlanta, Georgia might smell the area and dislike it immediately. Preference of smells pertaining to a community can be as specific as between counties or cities in the same state or as general as between nations or ethnicities.
Smell is similar to taste, touch, hearing, and vision in the case that the sense provides information about an object or space. In addition, smell is similar to vision and hearing because it can be transmitted over a distance. However, smell is different than the other senses in that it can determine precise chemicals, and the brain must rely on memory and intrinsic knowledge to determine what those chemicals mean. Other senses, besides taste, can provide an understanding on the size and motion of an entity, but smell and taste cannot.
Because scent has such charged meaning, one should use the sense to either attract or repel, although it can also be used to create moments of variation in a space. However, it is important to limit the amount of the odor to ensure it does not annoy or put off the user. Because smell carries memory and specific knowledge, it should be limited in scope to defined locations and groups. For example, rich floral perfumes are appreciated by older generations, but the younger population tends to prefer simple and sometimes artificial odors over the complex flowery scents. So, the designer must define the target audience then release this at the specific points. Even those that appreciate a smell will grow tired of it over time.
We can describe smell by a few variables. These include, complexity–how many chemicals is it composed of, volume or amplitude–how much of this scent is in the space, qualitative value–what does the scent mean and to whom, and finally, frequency–is this a smell that occurs once a day, or is it something that you only smell in certain season?