NEW YORK (CBSNewYork) — Loss of the sense of smell is one of the least understood medical conditions.

Not only can it deny people one of life’s greatest pleasures, it can also be dangerous — even life-threatening.

A bouquet of flowers, the inviting aroma of a delicious meal, and the comforting smell of home are familiar for most, but what if you could never smell them at all.

“I felt bad about it, like I was missing something that everybody else had,” Diane Kapllani said.

Kapllani was born without a sense of smell. It’s a condition called ‘anosmia.’ She said she realized something wasn’t right when she saw others enjoy the smell of flowers.

“I tried, you know, to go up to them and put my nose in and I thought to myself, ‘like what are they talking about,’ like I don’t get it,” she said.

It could be dangerous too.

A cigarette that Kapllani threw out a car window blew into her back seat and started a fire — she smelled nothing.

“I was unaware,” she said.

Other drivers had to flag her down to get her attention

“I was shook up, I was very shook up,” she said.

Leah Holzel lost her sense of smell came on suddenly after a viral infection. She was devastated.

“The loss is momentous,” she said.

Experts said that sense of loss occurs because smell is connected to the part of the brain that controls emotion.

“When you smell something that reminds you of something long ago it’s as if you’re experiencing it again, and that’s a very powerful emotion,” Pamela Dalton of the Monell Chemical Senses Center explained.

For Leah it felt like all of that was gone.

“It was a very morbid feeling that I had lost everything around me,” she said.

Leah is using one of the only treatments available– breathing essential oils and spices — and using memory to help trigger the brain to remember certain things, like what roses smell like.

For those like Kapllani — who were born without a sense of smell — there are no treatments. She said that even if she can’t stop and smell the roses, she’s adjusted.

“I enjoy the colors of the flowers,” she said, “There’s other ways of enjoying everything without it.”

Loss of smell can also be caused by chronic sinus problems, nasal polyps, and head trauma.

A recent study by the Centers for Disease Control found that about 13-million Americans have some difficulty or can not at all detect odors.