Have you ever come home to the smell of a roast cooking and thought, yum!? You sat down to read the paper, and after awhile, you did not notice the aroma as much. Then, someone else comes through the door and comments about the great smell! You hardly notice at this point.
Our noses have evolved to screen out consistent smells in an area we inhabit for several minutes. This allows us to focus on new or more subtle smells that might spell danger or opportunity. Those bits of information would otherwise be overpowered by the dominant smell we first noticed.
If you left the house and went to get the mail, when you returned you would notice the roast again as soon as you opened the door. Our sense of smell resets in this manner. However, if you had roast every day, your nose would eventually screen much of that aroma out as a background odor natural to that environment.
FATIGUE FOR FRAGRANCES
The same is true of fragrances in the workplace, and the fact they are noticed less over time is called "olfactory fatigue." Olfactory fatigue is why you get a complaint that an air freshener is "broken" or "empty," go to the room to check, and find it is full and functioning just like always. The problem is in the words, "just like always."
SOLUTION: ROTATION AND COMBINATION
The solution is fairly simple - rotation and combination of fragrancing. As long as the fragrances continue to change periodically, noses will continue to acknowledge them. One of our manufacturers has developed a fragrancing system where two different fragrances can be alternated or paired to keep noses guessing. The result? A reduction in complaints about air freshening.