Baffled city investigators began calling them “maple syrup events”: mysterious waves of sweet-smelling air that periodically wafted over Manhattan, delighting some, troubling others and vanishing as quickly as they had arrived.
After each episode — in 2005, 2006 and again this year — residents flooded the city’s 311 information hot line with calls. The city’s Department of Environmental Protection dispatched air testers. But nobody could pinpoint the smell — or its source.
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