Smell and odor nuisance, what is that?

As Aerox we offer our clients sustainable solutions for the reduction of industrial odor emissions. In the conversations we have with our contacts we often receive questions about how this exactly works, what smell actually is, why something stinks and why we actually are in this market.
Hence it is interesting to consider what odor and odor nuisance actually are. In this article we have responded to the questions: What is smell? Why do you smell this? And when is smell a stench?

Sense of smell

Humans smell with the nose, or better described with the olfactory epithelium. The olfactory epithelium is a piece of fabric at the top of the nasal cavity. In the epithelium are foothills of nerves, the olfactory receptors. When you smell something, these are volatile and in water and fat soluble substances in the air, which are detected by a binding to an olfactory receptor in the nasal cavity. This gives a signal to the brain which then confirms that the smell is observed.
 
Smell is used by people much more than we think. Humans have about 400 smell receptors, which can detect different odors. Where initially it was believed that people can discriminate approximately 10,000 different smells, recent publications indicate calculations showing numbers of over a trillion (Science, March 2014, Humans Can Discrimination More than 1 Trillion Olfactory Stimuli). The smell receptors are directly connected via holes in the skull to the olfactory bulb (Lat: bulbus olfactorus) in the limbic system in the brain.
 
Sense of smell is our only sense with such a direct connection. From an evolutionary perspective, the limbic system is an older part of the brain that amongst other things is involved in emotions and emotional memory, but also in primary defense responses. Certain odors can directly call for a defense response and that's a good thing. After all, it can be an odour that is related to direct danger or a substance of a hazardous nature.
 
Other fragrances just do the opposite and evoke positive responses. The experience of the vast majority of all odors however, depends on what one has learned and how something is labeled. This is the reason that smells sometimes call for strong memories or reactions. These have influence on our mood and with that also our well-being.

Smell

Natural odors are almost always composed of multiple different odor molecules, sometimes even hundreds. With artificial odors this is often not the case as these consist of 1 single or a mix of only a few substances. Artificial odor substances are added to products with the aim to add particular odor to a product. However, our advanced olfactory system and registration in our brains is almost always able to recognize the difference between natural and artificial products.
 
Natural or artificial odors where we suffer from give us a negative perception. These odors are called smell and of which the perception can have a very personal nature. What one person can see as an odor, for another person this is a smell. Of course there are also odors, such as sewerage air, which everyone classifies as stench. Pleasant scents, such as those of coffee, however can also be experienced as stench. This usually happens as the concentrations are strong: not a single fresh cup of coffee but from a chimney of a factory. Stench is hence "a negative odor perception".
 
Aerox is already active in this specific and very interesting market for decades. You can guess the reason why: the environmental and social importance of industrial odor reduction. Ever increasing urban sprawl does come with a field of tension between industry and residential areas. Both are and will remain necessary and all parties must therefore work together and take their responsibilities.
With our specific in-house knowledge we have very good relations with all of our customers who fully endorse this approach. Obviously we will keep on doing so whilst knowing that the end result of our efforts ensures fresh air in the direct environments of our customers worldwide.

Erik C. Versteeg, Managing Director, Aerox B.V., April 11th, 2017