"Can't you smell that smell?"

I could perhaps understand this happening in København but it is rather suspicious in New York City. A lingering odour, similar to the scent of gas, was reported yesterday in parts of Manhattan and northern New Jersey*. City officials said that they did not know what it is but that it wasn't harmful. Sort of like NY air quality after 11 September I would imagine.

*I can see people noticing this in Manhattan but how in God's name can you detect a specific, new smell in North Jersey?