NEW ORLEANS — At almost 300 years old, somewhat moldy from the remnants of Hurricane Katrina and surrounded by muddy water and swamps, this city is not exactly known for being lemony fresh.

The signature scent around Bourbon Street, after all, is the smell of spilled liquor.

But from the French Quarter to New Orleans East, people here have been complaining about a tinge to the air that is unsettling even by local standards.

Many suspect that it has something to do with the oil disaster in the Gulf of Mexico, which has already leaked millions of gallons of crude about 50 miles off the Louisiana coast. The authorities involved in the cleanup of the fallen Deepwater Horizon oil rig have been burning oil on the surface of the gulf and using chemical dispersants around the leak.

Could New Orleans possibly be smelling that, from more than 100 miles away? Many say yes. But the mystery odor, which is stronger on some days and in some areas than others, is hard for residents to describe.