I am in my kitchen smelling dirt. Three new plants -- a white kalanchoe and two red begonias -- sit on a stand at my window. It is April, nearly a decade ago, and I have bought them because it is finally spring. I admire their small, dense flowers and green, waxy leaves. But I hadn't planned on their powerful, raw smell. Working around the house, I try to think about something else. When I go upstairs, the smell follows me, earthy, pushy, almost wet. I wonder how it is that I can smell three small houseplants on the floor below. That afternoon, at the grocery, I can't shake their dank odor. Could the smell somehow have gotten into my clothes? A day later, miles away at my doctor's office in Manhattan, I am shocked that it smells there, too. But she has no potted plants. I finally get it. This assertive smell, my uninvited companion for almost two days, is inside my head, not out. Mortified, I think I must smell. Talking to friends, I cover my mouth with my hand. I brush my teeth more often, swish mouthwash compulsively. But my husband says I smell fine -- no bad breath. I finally call my doctor. I discover that I suffer from phantosmia. 'Osmia,' from the Greek osme, means 'smell.' Coupled with 'phanto' (like 'phantom'), it refers to an illusory sense of smell. I smell a smell when no odorant is present. Inevitably, medical tests followed. I had an MRI of my brain (ruling out a tumor), then a CT scan of my sinuses (looking for infection), and finally, an EEG (olfactory hallucinations do occur in epilepsy). The results were negative, and two rounds of antibiotics (was there a hidden nasal or sinus infection?) constituted my only -- and fruitless -- treatment. One day a year later I realized that the earthly smell was finally gone. But to my dismay a new smell immediately took over. My husband had burned a big pot of chili. Burned chili became my new default odor. At least it smelled better than dirt. Then, about seven years ago, a trip to Provence erased the chili. Lavender wafted in the air, becoming my new smell du jour. Southern France's lavender-infested landscape -- dried bouquets, scented soaps and candles, even flavorings for food -- trailed me back home. Some might think me lucky -- lavender is hugely popular. But I hated this smell that had squirmed its way into my brain. I tried in vain to fool my nose. Holding lemons under my nose didn't kill the odor. Smearing pungent perfumes and lotions around my nose didn't work either. A powerful odor like ammonia might trump the lavender for a moment, but that cure is worse than the disease. For a couple of years now, the smells have varied, some stronger than others. What's new is that these smells are only fleetingly connected to the outside world. Hints of ammonia but definitely not ammonia. Touches of a paper mill in their assertiveness but not quite that paper mill stench. When I smelled burned chili, I knew chili was out there somewhere. When I sniff my current guests, I can't connect them to the real world. They spook me like a phantom limb. Sometimes I can't tell whether a smell is inside or outside my head. Walking my dog, I cried as I smelled manure, convinced it would lodge in my head. At home, I rejoiced that the stink was gone. The next day, the horrid smell reappeared at the same spot. This time I noticed the warning sign: Gardeners had spread fertilizer. Only then did I know the smell was real. Avoiding gruesome odors is my first line of defense. There's a coffee shop nearby that I simply won't enter. It's jam-packed with wooden barrels of reeking coffee beans; locals complain they can smell the roasting blocks away. I send my husband to buy coffee while I wait in the car with the windows up. I've tried the opposite tactic, going out of my way to imprint favorite perfumes, fresh flowers, that wonderful bakery smell. Alas, my phantosmia specializes in the disagreeable. That is typically the case, I now know. Dr. Donald Leopold, chairman of the department of otolaryngology at the University of Nebraska Medical Center in Omaha, has studied smell disorders for 30 years. In phantosmia, Leopold says, both the upper nasal passages and the brain play a part, especially the brain, 'where the actual smell perception is generated.' Almost always the patient has lost some ability to smell. Leopold says that the brain, 'which has a propensity to make smell,' overcompensates by offering up odors, usually disagreeable ones, that may have existed previously but were suppressed. It appears that certain 'traffic cop' neurons, which had worked to exclude such odors, turn off. Though Leopold assures me that 'treatment is available,' I haven't tried the nasal saline drops, antidepressants, antiseizure medicines or sedatives recommended by one doctor or another. Mainly I try to think past the phantosmia, forcing my attention elsewhere. If that fails, I try to laugh at it, more absurd than awful. I win more of these skirmishes than one might expect. I learn that this disorder is best kept private. Some friends squirm when they hear about it, as if I were crazy. For that matter, phantosmia is linked to certain psychiatric disorders (schizophrenia, depression, Alzheimer's), but I don't have them. I do wonder, though, what it means to hallucinate smell. Those neurological explanations aren't entirely satisfying. There's nothing plainer than the nose on my face, but nothing more mysterious, either. 