Modern life could be putting health at risk by damaging our sense of smell
Traffic pollution, uncollected rubbish and messy homes are all having a harmful effect on the nose, says Dr Kara Hoover, an expert in olfactory evolution.
Having an impaired sense of smell increases the risk of mental problems such as anxiety and depression as well as obesity, she maintains.
Speaking at the American Association for the Advancement of Science (AAAS) annual meeting in Boston, Dr Hoover said: "Our sense of smell evolved in a very rich landscape in which we were interacting regularly with the environment.
"Now today we're not interacting with the environment and we're in very polluted places. Pollution is disrupting our sense of smell.
"That means it puts you at greater risk for things like mental health disorders such as depression and anxiety and it also puts you at greater risk for physical health problems such as obesity.
Scientists believe that pollution could be disrupting our ability to smell
"It also puts you at greater risk for social health problems – not being able to pick up on social cues from other human beings."
Our sense of smell seems to be very similar to Neanderthals
Dr Kara Hoover
Loss of smell sense was linked to poor mental health in a number of ways, Dr Hoover pointed out.
She said: "People who have suffered from a loss of smell have increased anxiety over their own body odour because they don't know if they smell bad or not.
"They're anxious about not being able to smell danger like gas leaks or smoke.
People who have suffered from a loss of smell have increased anxiety over their own body odour
"They suffer from poor quality of life and depression because they're no longer engaging with food (or) loved ones in terms of their sense of smell."
Studies had also shown a link between smell loss and obesity.
"If you have an impaired sense of smell you're getting sated more from taste and seeking richer tastes; salty and fatty food," said Dr Hoover.
One study of adults with a very strong sense of smell found that they tended to have low body weight.
10 common health myths Thu, November 10, 2016
Here are 10 common health myths that most people think are true.
Play slideshow Getty 1 of 11
Common health myths and old wives' tales
People from more disadvantaged backgrounds are more at risk because of their greater exposure to pollution, she believes. Bus passengers were eight times more exposed to traffic pollution than car drivers.
Similarly, people forced to live in dirty and polluted areas, or whose rubbish was not collected regularly, were likely to suffer more smell impairment.
She wanted to see more "greening" of cities to provide a healthier smell environment.
Bus passengers are eight times more exposed to traffic pollution than car drivers
Dr Hoover has conducted new research comparing the smelling ability of Homo sapiens with two now extinct human sub-species, Neanderthals and Denisovans.
She made the surprising discovery that the Denisovans from Siberia had a "less functional" sense of smell compared with early modern humans and Neanderthals.
Dr Hoover said: "Essentially, they can't smell grass, so this might suggest that they have a different adaptation.
"Our sense of smell seems to be very similar to Neanderthals'. They respond to odours the same way as us."