Some sufferers of phantosmia (one form of olfactory disorders collectively known as "dysosmia") smell rotting corpses. Others smell garbage or rotting food. Imagine biting into a big piece of chocolate cake, only to smell phantom dog poop. Or leaning over to sniff a rose that smells like a dead rodent.
I'm one of the lucky ones. I smell smoke that isn't there. That's better than not smelling smoke that is there - at least from a safety standpoint. Though nothing is burning, my throat closes and my lungs balk at deep breathing. My eyes water. It seems...real. I no longer have to ask family, friends, and coworkers, "Do you smell smoke?" I recognize the phantom - a slightly plastic, chemical smoke. The first time I smelled it, I was driving home from work. The air conditioner was on. I immediately thought the car was on fire. I watched for any signs of malfunction, the slightest whiff of smoke, any sign that the electrical system was on fire. I didn't panic, but I kept my eye on opportunities to pull over and ditch the car. A car burns fast.
I made it home, where I lifted the hood of the car and did a 360-degree visual inspection of the car. Nothing out of the ordinary.
I still smelled it an hour or so later. Only this time, I was in the kitchen, cooking dinner. I calmly inspected the appliances, checked the oven and stove for burning grease or food, and made sure I knew where the fire extinguisher was. It was puzzling. I asked my husband if he could smell anything burning. He said no. I asked the kids. Nope. I pulled open the trap-door to the attic. It smelled of sun-warmed wood, insulation, and cardboard. Not smoke. In fact, the smoke smell was easily subsumed by the odors of food cooking, the smell of warm attic, a spritz of perfume. Again, it turns out that I'm one of the lucky ones: I still taste and smell other things quite normally. I can even overwhelm this phantom smoke with real scents. Last night, it was a little smear of Mentholatum on each nostril, just like they do in the morgue. It's not that the smoke smell, itself, is so awful; the worst part is the choking and the watering eyes. That makes it hard to sleep.
Types of smell disorders range from anosmia (lack of a sense of smell) and hyposmia (decreased sense of smell), to hyperosmia (overly sensitive sense of smell), parosmia (smelling the wrong thing), and phantosmia (smell hallucinations). Causes include upper respiratory infections, head injuries, nasal polyps, sinus infections, hormonal imbalances, dental problems, certain medications, exposure to some types of chemicals, brain tumors, and radiation treatments for head and neck cancers - to name a few. Apparently, dysosmia can be a symptom of a deadly medical problem - or an end in itself. Clearly, it's important to consult your doctor - and possibly an ENT or neurologist - to rule out more serious physical problems. It can also be psychological.
If you suffer from phantosmia, it's a good idea to keep a journal detailing the smells: what time they hit, what they smell like, what might have triggered them. Brewing coffee is a reliable trigger for me; stress seems to make phantosmia more likely to occur. There is some indication that consuming soy also triggers phantom smells. You may be able to get some relief from the symptoms by using a saline nasal wash. It is recommended that you do this on all fours, with the top of your head down on the floor, for maximum effect. Track the results - you may discover other things that cause the smell or things that make it go away. Once your doctor has ruled out things like brain tumors and nasal polyps, you may be your own best resource in alleviating the symptoms.
If you have experienced the symptoms of a smell disorder, drop by the Parosmia/Phantosmia group on Yahoo - you're not alone. There's lots of information and support there.