JERSEY CITY Environmental officials in two states said they have given up hope of finding the source of a mysterious odor that swept across parts of New York City a week ago.

New Jersey officials said they checked out more than 140 industrial facilities in the northern part of the state to see if they were responsible for the foul stench that drifted up the Hudson River on Jan. 8.

The inquiry didn't turn up any unusual emissions, said Elaine Makatura, a spokeswoman for the state's Department of Environmental Protection.

New York City officials analyzed air samples taken during the hours when the invisible vapors lingered over Manhattan, Brooklyn and Staten Island and also came up empty.

"We have done the extensive lab analysis, and there is nothing conclusive as to a particular chemical signature from the samples we took," said Charles Sturcken, a spokesman for the city's Department of Environmental Protection.

Pressed for details on what the city was doing next, Sturcken said that unless the bad smell returned, it was finished with the matter.

"The investigation of the odors from last Monday has been concluded," he wrote in an e-mail.

Officials in both states began their inquiries the morning of Jan. 8, when people on Staten Island began calling authorities to complain about a pungent smell that some feared was leaking natural gas.

Within minutes, similar complaints were being called in across the harbor in Manhattan, then as far north as the George Washington Bridge. People in two New Jersey counties, Bergen and Hudson, were reporting the smell by 11 a.m.

Then the stench dissipated.

Mayor Michael Bloomberg suggested that the vapors smelled like mercaptan, a chemical added to odorless natural gas so people can detect leaks.

There was also a theory, early on, that the smell might have come from vegetation decaying in coastal wetlands, but Makatura said New Jersey officials found no evidence to support it.

To date, investigators in both states say they have no idea what the gas was or where it came from and are largely out of leads to check.

"Odors are elusive," Makatura said.