When many folks go about looking for a source of a smell, we check the usual suspects first: The garbage can. The pets. The bathroom. The children. You know — all the usual places.

However, for an estimated 6.5 percent of Americans over the age of 40, the struggle to locate where an odor is coming is more difficult simply because the smell doesn't actually exist.

This phenomenon is called phantom odor sensation, and thanks to a study published in the journal JAMA Otolaryngology-Head and Neck Surgery, we know for the first time how widespread this particular medical condition might be.

Can you smell that?

To determine the prevalence of these phantom smells, researchers turned to data from 7,417 participants over 40 years of age from the 2011-2014 National Health and Nutrition Examination Survey (NHANES). The participants in this survey were asked a simple question: "Do you sometimes smell an unpleasant, bad, or burning odor when nothing is there?"

Researchers took the answer to that question and then factored in the standard variant characteristics of the respondents: Age, sex, education level, race/ethnicity, socio-economic status, certain health habits and general health status.

Senior woman leans over and smells flowers outside Women over the age of 60 were less likely to experience phantom smells compared to women between the ages of 40 and 59. (Photo: wavebreakmedia/Shutterstock)

Among the participants, 534 reported experiencing these phantom smells that no one else around them could smell. Rather surprisingly to researchers, the phantom smells lessened as people aged. Women over the ages of 60 and 70 reported fewer instances of detecting these non-existent smells, while women between 40 and 59 were more likely to experience them. Women were twice as likely overall to report phantom smells than men, but researchers are unable to explain this discrepancy.

A Swedish study, published in 2017 in the journal Chemical Science, also found the phantom smells to be a more comment occurrence among women compared to men.

Quality of life played a part as well. Phantom odor perception was 60 to 65 percent more likely among those who reported an income-to-poverty ratio of less than 3 compared to those in the highest ratio groups. The low socio-economic status of these participants may increase their chances of being exposed to environmental or chemical toxins that contribute to the phantom smells. Certain health conditions, like persistent dry mouth or history of head injuries also contributed to the likelihood of experiencing phantom odors.

Sniffing out the cause

A refrigerator full of fruits and vegetables Phantom odors can affect your ability to detect spoiled food — though there doesn't appear to be a speck of it in this particular fridge. (Photo: Anna Omelchenko/Shutterstock)

Smelling odors that aren't there can seem like just an annoyance, but it can have serious ramifications for overall well-being.

"Problems with the sense of smell are often overlooked, despite their importance. They can have a big impact on appetite, food preferences and the ability to smell danger signals such as fire, gas leaks and spoiled food," Judith A. Cooper, acting director of the National Institute on Deafness and Other Communication Disorders (NIDCD), said in a statement.

The NIDCD helped to fund the data collection efforts of the study.

Researchers hope this whiff of information will help further awareness and potentially more research regarding phantom smells.

"The causes of phantom odor perception are not understood," Kathleen Bainbridge, a member of the epidemiology and biostatistics program at the NIDCD and lead author of the study, said. "The condition could be related to overactive odor-sensing cells in the nasal cavity or perhaps a malfunction in the part of the brain that understands odor signals.

"A good first step in understanding any medical condition is a clear description of the phenomenon. From there, other researchers may form ideas about where to look further for possible causes and ultimately for ways to prevent or treat the condition."

One in 15 Americans detect phantom smells
6.5 percent of Americans over the age of 40 experience phantom odors, but we're not sure what causes this sensation.