The smell was first reported from areas along the north coast of San Diego County Wednesday afternoon.
The County Air Pollution Control District said Friday that while the smell was annoying, it was not dangerous and did not pose a public health risk.
Bob Kard is the director of the County's Air Pollution Control District (APCD).
He said samples tested from areas where the odor was smelled showed only normal and low background levels of 56 hydrocarbons and 48 different types of toxic air contaminants.
“In other words, the results were very good news," said Kard. "Nonetheless, we know the odors were out there and bothering people.”
Kard said the Air Pollution Control District continues its effort to trace the source of the mysterious smell.
He said the District is plotting complaints and wind information in the hope of identifying a geographic origin.
But Kard said the process could take a week and may mean little since the odors have gone away.
Calls came into various agencies Wednesday complaining of a heavy odor that they described as fuel-like in varying degrees, from gasoline to kerosene.
County inspectors immediately canvassed the areas to try to locate a source and APCD staff collected samples to test.
APCD officials also contacted the Navy, Coast Guard, Camp Pendleton, Lindbergh Field and the Federal Aviation Administration, which all reported they had no idea what the source of the odor might be.
