Answers are emerging about the strong odor that unsettled residents—particularly in the southern suburbs of Athens—in mid-May. Following an extensive investigation, the AtmoHUB scientific team of the National Observatory of Athens has identified what it considers the most likely source of the phenomenon.
According to the researchers, the trail of the smell, which was especially noticeable across southern Attica, leads to the Saronic Gulf, specifically the maritime area southeast of Salamina Island.
The prevailing hypothesis is that the odor was linked to an LPG (liquefied petroleum gas) carrier operating in the area, with the released substances most likely being propane or butane.
To pinpoint the source, scientists analyzed 164 reports submitted by residents and combined them with high-resolution meteorological data.
As explained by Vassilis Amiridis, Research Director at the National Observatory of Athens and head of AtmoHUB, the team employed three-dimensional atmospheric models to reconstruct the movement of air masses and effectively “rewind” their trajectory. The analysis showed that the gas plume spread from coastal areas toward the east, west, and north, with the strongest impact recorded between noon and 3 p.m. on the day of the incident.
Amiridis noted that propane and butane are naturally odorless. However, suppliers add mercaptans—chemical compounds with a distinctive smell—to make any leaks immediately detectable.
He was unequivocal regarding public safety: “In any case, propane and butane are neither toxic nor dangerous to humans.”
Researchers also ruled out the possibility that the odor originated from natural gas or from natural environmental sources.
Alternative Theories and Official Response
Researchers briefly considered whether the odor could have originated from Psyttaleia and been carried by westerly winds, but available evidence and residents’ reports make that scenario unlikely.
Authorities have yet to issue an official conclusion. While the Hellenic Coast Guard inspected gas carriers operating in the area, no irregularities were found.
Scientists noted that the absence of air sampling during the event leaves some uncertainty over the source. Greece’s Environmental Inspectorate said the incident fell outside its remit, which is limited to liquid and solid pollutants.
AtmoHUB, coordinated by the National Observatory of Athens and supported by the Copernicus CAMS programme, is Greece’s main atmospheric monitoring and information platform.
