There were reports in the Tel Aviv and the Sharon region of a strong chemical smell on Thursday.
Most complainants reported a strong smell of chlorine or bromine, or insecticide.
While most residents simply closed their windows and remained calm, others became concerned there had been a chemical attack.
Police and city administrations in the region received numerous calls, and Environment Ministry officials were dispatched to take readings.
The officials reported low concentrations of gas in the air, which they say do not pose a danger to public health.
"All measurements in the Tel Aviv area are negligible," they reported. "The Environmental Protection Agency is continuing to perform measurements, and trying to locate the source of odors. We are continuing to monitor other areas too."
The officials also stressed they had yet to identify the souce of the smell.
However, a local environmental consultant told Channel 10 that concentrations producing a pungent scent were not healthy.
"This is an exceptional case," the consultant said. "Such chemicals in high concentrations can be dangerous. The smell is quite strong."
"The city administration could not identify the source," he added.
However, the IDF Home Front Command identified the source of the smell as drilling off the coast of Ashdod.
Ramat Hasharon Mayor Itzik Rochberger complained that while the HFC told him the source of the smell, officials from the Environment Ministry were still in the dark.
"If it were a harmful substance what would happen?" he asked. "Why is no synchronization between the government systems?"