While riding my bike back home after bringing my little daughter to school along the Acropolis walkway “Dionisios Aeropagitou” yesterday morning, I came across an Air Pollution phenomenon that was so clear that I had to make a video of it. So I rushed home to get the camera and went back to document it.
The Air quality changed so dramatically along the way from Plaka (right in the map here below), just below the NE slopes of the Acropolis, to home in Thiseio (left in the map), in just about a kilometer of distance in a straight line. The Air was 5 times more polluted at home than at the school! How could this be?
It is really surprising that even within a pedestrian zone and a green park in central Athens, the Particulate Matter (PM2,5) in the air could increase fivefold from 10 to 50 μg/m3, which is a very big difference, in just such a small distance.
The phenomenon is explained by the action of a morning breeze that blows dirty Air from the central part of the Athens’ plain. These nights we are living what I describe the “Airmageddon“, with severe Air Pollution (with peaks of PM2,5 above 300 μg/m3!) due to thousands of wood stoves and fireplaces that are lit allover the city. The smoke is intense everywhere, but especially in the lower, central part of the plain (see map below).
As such, the morning SW breeze blows the dirty Air filled with PM2,5 towards the southern and western parts of Mt. Filopappou, where it gets partially trapped on its slopes. But the breeze doesn’t immediately reach Plaka, which lies below the steep eastern and northeastern side of the Acropolis and is therefore protected by both hills.
The phenomenon yesterday lasted for not too long, because about one hour later most of Athens was clean after the wind got a bit stronger and finally blew all residual wood smoke away .
This phenomenon actually happens several times in winter, when the weather is fair with a SW breeze as the main wind, which simply pushes the dirty Air towards the Filopappou Hill, making its Air temporarily dirtier, until it is finally blown away later on. If the wind picks up during the day, like during these past two days, then it manages to clear out the air completely so that we can enjoy clean air during a few hours until the evening comes and residents light their fires again. If the breeze remains light, then the air doesn’t clear out and in fact the Particulate Matter builds up, making the next days and evenings even more polluted – until a new wind or rain comes and clears out the air again.
But isn’t it really terrible that in 2021, amid a deadly COVID pandemic that attacks our very respiratory and circulatory systems like Air Pollution does, we have to still “hope” for a good windy or rainy day in order to have clean air in our cities? For how many more years do we have to endure these Airmageddons? Hasn’t time finally come to start acting to clean out our dirty Air ourselves?
These local situations with Air markedly more polluted in one part of the city compared to a nearby area can be found in many cities around the world, where the geography and dominant winds play their role to increase or decrease the Air Pollution.