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.Link