Does it smell like olives? The Lisbon region has an unpleasant odor, but its origin is unknown.

This Tuesday, the Lisbon region experienced an unpleasant odor with “pungent/olive characteristics”, “not typical for the location”, which is the result of weather conditions, including wind, and its origin is currently unknown, according to air exchange data. quality researcher.

“We have a number of meteorological characteristics that enhance the perception of odors, especially in the last week and even into early January. […] which has acrid/olive characteristics and is therefore somewhat atypical for this location,” said researcher Sofia Teixeira from the air quality department of the Faculty of Science and Technology of the University of Nova de Lisbon.

In a conversation with the Lusa agency, the researcher indicated as meteorological characteristics a record of winds blowing from the south-southeast quadrant, with “a very low thermal inversion, due to which the gases themselves are retained in the lower atmosphere” and which can further absorb odors.

In addition, there is a “moderate wind intensity that favors the dispersion of air masses to more distant places”, pointed out Sofia Teixeira, noting that the combination of these meteorological characteristics means that in the wider region, including for example Sintra, Almada and Sesimbra, this a type of acrid/olive odor is detected at the same time.

The existence of a mass of air coming from the deserts of North Africa and carrying suspended dust, which is expected to cross mainland Portugal this Monday and has prompted the Directorate General of Health (DGS) to recommend it to the general population. avoid prolonged exercise and physical activity outdoors, and for older people and children to stay at home, the researcher explained that this perception of odors “has nothing to do” with these particles.

When asked about the origin of this unpleasant odor, which is felt in the region of Lisbon and the Tagus River Valley, the researcher replied that “it can spread to different industries, but the most common may be the olive pomace processing industry or even waste recycling.” “.

Regarding the possibility of odors coming from the landfill, it is known that when it comes to waste, the distribution of odors is “much more concentrated in a specific location and not so dispersed throughout the Lisbon and Tagus Valley region.” .

“Therefore, most likely [o odor] could be associated with a fixed source and that, in combination with these very specific meteorological conditions, could contribute to this detection at the same time in these different locations,” added Sofia Teixeira.

Air quality researchers are trying to determine what processes lead to this type of odor and what activities are part of the source of emissions that contribute to the perception of unpleasant odors.

“We suspect, although without much certainty, that this may be a source of emissions from somewhere south of Lisbon and the Tagus Valley region, so Alentejo can only be a hypothesis,” the researcher said.

Identifying the sources of emissions will allow us to understand what can be done to minimize the effects of the odor, although in Portugal there are no legal regulations governing such cases, he stressed.

“What we do is we map the locations, which have been received from citizens who have complained through social media, for example, and then, later, we try to identify two or three possible sources of emissions and go to the sites and assess the situation.” – he said.

Regarding the consequences of this type of odors, Sofia Teixeira stated that “they do not have a direct impact on human health, but are consequences caused by the inconvenience of perceiving the type of smell” and restrictions in carrying out certain activities, for example, opening a window at home or being able to breathe air. which doesn’t smell like that.