The nature of the mysterious odor detected in Tel Aviv and Herzliya areas during the last month has been revealed, as Environmental Protection Ministry tests have pointed to the toxic chemical bromine, Maariv reported Thursday.

After the smell was first noticed by hundreds of thousands in Tel Aviv on May 3 — prompting feverish speculation about chemical attack and concerns about health threats — air samples were sent to various laboratories, and the results were analyzed by ministry experts and academics.

The results contradict the initial claims of a ministry official who said with “almost certainty that the smell poses no danger to citizens,” as bromine is a toxic element that is usually transported in steel tanks; exposure to it can cause respiratory difficulties and even death in extreme cases.

Environmental Protection Ministry officials said the substance was found in varying concentrations in different places on the days the smell was noticed. The officials refused to comment on the possible source of the chemical, saying a criminal investigation is ongoing and no further details of the case can be released at this point.