You might put a freestanding deodorizer wherever there is space on a shelf. Being in the same room may seem sufficient, but whether odor molecules reach the product also depends on airflow and furniture placement.
A study published in 2014 examined placement in a small model space representing a kitchen with a counter facing the adjoining room. Its findings suggest that understanding a deodorizer’s performance requires looking at the space where it is used as well as the product itself.
Moving beyond performance inside a bag
The main aim was to explore a method of evaluating deodorizers under conditions intended to represent living spaces. The industry test discussed by the authors at the time placed a deodorizer in a sealed 10-liter bag containing an odorant and assessed its effect.
Bag tests have the advantage of measuring a product’s capacity under standardized conditions. In a room, however, ventilation continues and furniture and walls alter air movement. Some locations can have more odorant than others. Could an evaluation method account for these uneven concentrations?
The paper was written by Kotaro Kitajima, Yasuyuki Hasegawa and Eizo Murakami. The first two were affiliated with Kobayashi Pharmaceutical and Murakami with Asahi Kogyosha. It is a technical paper by industry-affiliated researchers.
Creating uneven odor concentrations in a two-cubic-meter model
The team built an acrylic test chamber with a volume of 2 cubic meters. Inside were obstacles representing a kitchen counter and part of a wall, together with a cylinder representing a waste bin.
Hydrogen sulfide was supplied continuously from inside the cylinder under fixed conditions, with ventilation set at 0.5 air changes per hour. Sensors at 5 locations tracked local concentrations. Beforehand, each sensor’s output had been calibrated against hydrogen sulfide concentrations so its readings could be converted into concentration values.
The product tested was a freestanding deodorizer that acts when hydrogen sulfide comes into contact with it. It did not disperse deodorizing ingredients into the surrounding air. This distinction helps explain why changing its location might matter.
The following three conditions were compared, each measured over 15 hours:
- No deodorizer
- A deodorizer placed in the high-concentration area
- A deodorizer placed away from that high-concentration area
This was neither a test with real food waste nor an assessment by people smelling the air. It involved just one odorant, hydrogen sulfide, and measured its airborne concentration.
Lower concentrations nearby were accompanied by changes farther away
Without a deodorizer, hydrogen sulfide concentrations became high between the cylinder representing the bin and the obstacles. Concentrations were lower at other measurement points, creating an uneven distribution within the model.
When the deodorizer was placed in the high-concentration area, the concentration immediately nearby was approximately 75% lower than without the product. At around 800 minutes, the value used for comparison by the authors was approximately 0.45 ppm. Concentrations at the four more distant measurement points were also reported to be roughly halved.
Although the product acts locally, readings fell farther away as well. The authors suggest that hydrogen sulfide was removed near the deodorizer, reducing the amount available to spread elsewhere. Their explanation was not that deodorizing ingredients traveled to those distant locations.
When the product was placed away from the high-concentration area, however, concentrations at the measurement points were approximately 90% of those without a deodorizer: a reduction of only about 10%. The same product produced substantially different reductions depending on its position in this model.
The second position lay where clean air could pass relatively easily. The authors suggest that the deodorizer may have had insufficient contact with hydrogen sulfide, limiting removal. This is an interpretation of the concentration results, not a direct measurement of airflow and contact rates.
Placement is also a question of how performance is measured
The study captured placement-related differences as concentration changes at multiple points. This allowed the evaluation to include spatial variation that a single measurement might miss, along with effects away from the product. The authors concluded that the results showed the potential to develop a performance test representing use in living spaces.
However, the two-cubic-meter model did not reproduce a real room completely, a limitation the paper itself identifies for future work. Results could change with room size, ventilation, obstacles, odorants and product mechanism. A percentage reduction in concentration is also not a percentage reduction in perceived odor strength or unpleasantness.
The everyday lesson for contact-based deodorizers is to ask whether odor molecules can reach them. These results cannot establish an optimal position for every home or guarantee the same percentage reduction throughout a room.
Conclusion
In this model experiment, a freestanding deodorizer did not work equally well wherever it was placed. Positioning it in the high-hydrogen-sulfide area reduced concentrations both nearby and at more distant measurement points.
The larger aim was to incorporate such spatial differences into deodorizer evaluation. Studying both product performance and the routes by which odorants travel can bring assessments closer to the conditions of everyday use.
References
- Kitajima, K., Hasegawa, Y., & Murakami, E. (2014). The research of the deodorizer performance evaluation method in the life space. Journal of Japan Association on Odor Environment, 45(6), 423–428. DOI and article details / Full research article (PDF).
