No explanation has been given for the smell that made its appearance from midday on Monday (18.05.2026) until the early hours of Tuesday in areas of Attica, causing concern among residents.
The origin of the mystery smell that blanketed Attica has yet to be determined. According to Nikos Michalopoulos, director of research at the National Observatory of Athens, so far no pollution has been found in the so-called “institutional pollutants”, meaning those substances for which there are limits and measurements at the European level.
According to what he said, the first data showed no alarming change in the key air pollution indicators. This fact led scientists to turn to analysing odour itself, which does not fall within statutory limits and is more difficult to measure.
As he said, such odours are generally associated with the presence of sulphur-containing chemicals, which may come either from human activities, such as industrial production, or from natural causes, including the marine environment. However, in this case the strong odour did not appear to be caused by a natural phenomenon.
Possible LPG leak
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As he pointed out, the possibility of a leak from natural gas installations has been ruled out, and the scenario of origin from the sea has been rejected, as according to Mr Michalopoulos, natural emissions do not present the specific odour described by citizens.
The most prevalent scenario for him is that it is an emission of LPG into the atmosphere, possibly from propane or butane, substances to which sulphur compounds are added to make them detectable in the event of a leak.
Nikos Michalopoulos did not rule out the possibility that the odour could have come from either marine activity – such as cargo dumping or a leak from a ship – or from a land-based source, such as the wider area of the Gulf of Elefsina.
“For it to be felt in such a large area and with such intensity, we are talking about a significant amount,” he noted, adding that all the data converge on the fact that it is not a natural phenomenon but a man-made emission, probably illegal.
Talking to Newsroom, he stressed that the precise identification of such incidents is particularly difficult. This is because Greece lacks the necessary specialised equipment to directly record compounds such as propane and butane in real time.
According to what he said, such measurements require high-cost equipment, while in many cases the analysis can only be done afterwards, which limits the possibility of immediate investigation.
