As many as one in 15 Americans over the age of 40 experience phantom odors. That's according to a study published in the journal JAMA Otolaryngology-Head and Neck Surgery. Sadly, these aren't scents of roses, freshly cut grass, and cooked bacon, but more unpleasant smells (think: burning hair, rotting eggs, and ashtrays). 

Phantom odors are a little-understood phenomenon and why exactly we get them is a bit of a mystery. Researchers suspect it is related to overactive odor-sensing cells found in the nasal cavity or even a glitch in the area of the brain responsible for interpreting odor signals, but this is still guesswork. We do, however, now know a little bit more about who gets them – and how prevalent they are across the US.

Researchers led by Kathleen Bainbridge from the National Institute on Deafness and Other Communication Disorders (NIDCD) at the National Institutes of Health (NIH) analyzed data from the 2011-2014 National Health and Nutrition Examination Survey (NHANES). In total, 7,417 adults 40 years and older were involved.

One in 15 (6.5 percent) reported having smelled a non-existent odor, a little more than what was found (4.9 percent) following a similar study in Sweden last year. But this result was not spread evenly across the entire population. Women, for example, were roughly twice as likely to experience phantom odors than men. It was also much more common among people from a lower socioeconomic background, with those in the lower income brackets 60 percent more likely to report phantom odors than those in the highest. The researchers suspect this may be because they are more likely to be exposed to pollution and toxins in their daily life.

Interestingly, age was also a big influencer, just not necessarily in the way you might expect. Women aged 40 to 49 or 50 to 59 (9.6 and 10.1 percent respectively) were more likely to report phantom odors than women aged 60 to 69 or 70 plus (7.5 and 5.5 percent respectively). The same was true for men: 2.5 percent of men aged 70 plus and 5.3 percent of men aged 60 to 69. 

Other factors that may put you at a higher risk include a history of head injuries, dry mouth, and poor overall health.

"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," Bainbridge said in a statement. Not only that, but the enduring presence of a foul stench can have quite a major impact on your quality of life. 

So, what now?

"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," Bainbridge added.

While the pervasiveness of phantom odors across the population suggests it's not always something to worry about, it can be a sign of an underlying problem. In the past, it has been linked to tumors, Alzheimer's, and epilepsy, for example. As always if unsure, it's always best to get it checked out!