The Science of Scent
Our sense of smell is a powerful thing. More powerful than most of us realize. Mostly, we think of scents as the pleasant fragrances that are part of our daily life, sometimes as an aerosol spray to cover up, or mask, the unpleasant odors around us. But “scent as fragrance” is just tip of the iceberg when it comes to what scent diffusion can really do for us, and to us. Scents can impact our moods, impact our health, and even improve our wellness and well-being.
Scent has the ability to trigger positive and negative impacts on our moods which directly affects behavior. When scent molecules are inhaled, our olfactory system sends information to the hypothalamus which then produces hormones. These hormones in turn create an emotional reaction which can be positive or negative, depending upon the type of scent. Scent is the most powerful, instinctual sense that we have as humans.
The use of scents to alter moods and affect our health, wellness, and well-being can be traced back nearly a thousand years. Using natural plant extracts to create essential oils that affect both our physical and psychological state is deeply rooted in many cultures. More recently, the application of natural essential oils is thought of as both an art and as a science. Today, the true power of scent, and the science of scent, is being applied not only to directly eliminating odors but as way to kill airborne pathogens such as viruses and bacteria.
Detecting and Eliminating Malodors
Malodors are the result of several classes of compounds: Nitrogen compounds such as smoke, garbage, urine, and seafood, and organic acids such as vomit, sweat, mold and mildew. Whatever their source, these smells are a very troublesome issue in the shared-mobility space, especially in rideshare and autonomous vehicles. Malodors are even more problematic in driverless (autonomous) vehicles where there isn’t anyone to personally monitor the cabin’s freshness on a ride-by-ride basis. The good news is – there are electronic sensors that can monitor and report that these classes of malodors exist in the vehicle. And in even better news is – there are active ingredients that can be released into the vehicle’s cabin air to eliminate the offending order, while also adding a fresh scent.
By combining special active ingredients with a dry-air scent diffusion, malodors can be eliminated in rideshare and autonomous vehicles. Sensors can also be added to continuously monitor the vehicle’s interior for offending odors based on these nitrogen and organic acid compounds and release a counter-acting malodor ingredient. The counter-acting malodor ingredient is a molecular compound that chemically reacts with the malodor molecules to create a new compound in the air with a different scent characteristic. Known to chemists as a Schiff or Michael chemical reaction, the resultant molecular compound is far less volatile, and has a much less offensive odor characteristic. Finally, an additional fresh scent can be added to the diffusion to further eliminate odors from smoke, garbage, and even pet biological evacuations.
Knocking out Airborne Bacteria and Viruses
In the same way that malodors can be airborne and molecularly present in a vehicle’s cabin, airborne pathogens such as viruses and bacteria can be prevalent as well. U.S. National Institutes of Health scientists from the National Institute of Allergy and Infectious Diseases (NIAID) confirmed in recent months that viruses can infect individuals through both airborne (aerosol) transmission and direct surface contact. Their tests demonstrated that when an infected individual coughs, sneezes, or talks, the virus is carried by droplets and remains viable and still able to infect others as an airborne-based pathogen for at least three hours. Anyone who is within 6 feet of that person can breathe those droplets into their lungs. These findings were released in a peer-reviewed article from The New England Journal of Medicine that included researchers from Princeton University, UCLA and the National Institutes of Health.
To counteract the transmission of bacteria and viruses in rideshare and autonomous vehicle cabins, testing has been underway on a variety of “active ingredients” that are known to reduce the effects of these oral pathogens. To thwart airborne bacteria, more than 14 unique essential oils have been found to have a beneficial effect on reducing 6 types of common oral bacterial pathogens. In the same manner, natural virucidal agents have been identified that are known to reduce the transmission of airborne viruses. Unlike some essential oils that have “antiviral” properties that inhibit the proliferation of a virus, a “virucidal” agent is an active ingredient that actually kills the virus.
Whereas malodor active ingredients cause a chemical reaction and a new compound to be formed with reduced odor characteristics, airborne pathogens are counteracted by virucidal active ingredients that deliver a destructive biological reaction – eliminating the pathogen in the air.
Recirculated Air vs. Fresh Air
For both rideshare drivers and passengers, the possibility of contracting a virus by breathing infected vehicle cabin air is quite real – even with protective plastic shields and a HEPA-equipped cabin filtration system. According to a study by the PNAS1, a person speaking loudly for just one minute could generate more than 1,000 virus-infected droplets. These droplets are small enough to hang in the air for as much as eight minutes as well as be moved around through the vehicle’s ventilation system.
Volker Braeunling, a global technical director of automotive filters at Freudenberg, said: “But in the ambient air, you don’t see a single coronavirus flying around because these viruses are in the droplets coming from a human being who is sneezing or coughing.” He further elaborated that the virus-ridden droplets evaporate quickly, reducing the virus particle size to the one-micron level. At such as small size, an airborne virus can be easily transmitted and particularly dangerous because “The [car’s] filter must have a high efficiency to capture these fine particles and droplets.2”
Viruses can be very small, about 120 nanometers, or .12 microns, in length in some cases. These airborne viruses normally begin as larger droplets from talking, sneezing, or coughing. But once these droplets evaporate, what is left is an airborne pathogen that is much smaller in size than any standard vehicle cabin filter can trap. Today, the majority of ventilation system filers can stop particles that are around 10 microns, while the best filters available can filter down to the 0.3 micron level. As such, as airborne pathogens are being inadvertently released by infected droplets, and then recirculated throughout the cabin’s interior through the ventilation system.
With the air-system set on “recirculate” in the cabin of a rideshare vehicle, airborne pathogens are potentially recirculating within the ventilation system from a previous sick passenger and/or sick driver. If a vehicle is recirculating the air within the cabin, this is especially dangerous for the diver as well as the next passenger, even if a plastic shield is between the driver and passenger. In today’s vehicles, most HVAC systems pull air from the lower front passenger side of the vehicle and push it to both the front of the vehicle, and to the back second row where the passenger is sitting.
When using the “fresh air” option, the air exits outside through vents at the rear of the vehicle. When the vehicle is moving, these exit vents are located in a low pressure area on the vehicle’s surface and essentially “pull” the air through the vehicle, providing constant flow-through. Using this setting means any airborne pathogens released by the driver are then circulating through the vehicle, past the passenger, on their way to the exit vent. Unfortunately, in this scenario, any plastic shield installed between the driver and passenger cannot contain that amount of airflow, defeating its protective purpose.
In many ways, scent diffusion systems are providing new in-roads into health, wellness and well-being solutions in the shared mobility marketplace. Through the unique combination of technology and natural active ingredients, the science of scent has officially arrived as an option to help combat both bacterial and viral airborne contagions in this fearful time.
Of course, it’s great to have an in-vehicle scent that is pleasing to our olfactory system, but now we have the means to use existing natural active virucidal ingredients that can directly affect our personal health, wellness, and well-being in our everyday lives. This allows for exploration in the new field of the science-of-scent that is seeing rapid growth and as a means to get rideshare safely rolling again.
Related “Wellness Ride” articles and announcements:
Rideshare and Wellness Ride: https://inhalio.com/markets/rideshare-scent-diffuser/