We all live downwind – Winter Air Quality in Greece

If you pay attention, in the image above you can see a village hidden within a thick layer of smoke. This is one of the many villages of the fertile Messenian plain north of Kalamata, home to hundreds of thousands of olive trees that produce one of the best olive oils of Greece, as well as the worldwide famous Kalamon black olives.

Unfortunately, this is also one of the regions of the country with the worse air in winter. You can see in the charts below how terrible its Air Quality is (Skala Messinia). Living there is unbearable, if you care about your health. But because most people have no knowledge of the pollutants they breathe, they keep on going on as if nothing really happens.

The example of the Messenian Plain was chosen in order to explain the major factors that affect the Air Quality in Greece during the colder season. By far, WOOD SMOKE is the No. 1 culprit that reduces the country’s Air Quality to levels among the worse of the EU. You just have to open the PurpleAir.com map during most winter evenings (see one example for December 04th 2021 here below) to understand to which extent the wood smoke pollution goes, over practically the whole of the mainland. The islands are less affected, but in reality there are no villages/cities on the whole Greek territory where there is no smell of wood smoke on a generic winter evening (and, in the colder regions, during the day too).

The Air Quality charts of Skala Messinia that we will see further below show very well that the wood smoke affecting so badly the country comes from two main sources: 1. domestic heating and 2. traditional farming practices. These two sources usually pollute the air at different times of the day: farmers burn tree remains (branches, twigs and leaves) discarded while collecting olives and other fruits in the fields during the daylight. Then, at night and when they wake up in the early morning, the same farmers but also an ever larger number of people in the cities, burn wood in wood stoves and fireplaces to warm up their homes. In Northern Greece and during the rare very cold days in the south, people keep the wood stoves on also during the day. In the south it is more common that people light their wood stoves only in the evening.

The result of all these traditional (or better, outdated) burning practices is that wood smoke is a constant feature lingering in the Greek Air of both cities and villages in every corner of the country, and even locations with a milder weather like the region of Kalamata must suffer greatly from it: at night because of the wood stoves that burn wood to warm up the houses, and during the day because farmers burn massive amounts of discarded tree branches and leaves to clean up their fields.

The toxic air in most Greek cities on the evening of December 4th 2021 was mostly due to a massive, uncontrolled burning of wood for domestic heating. Wood burning on a very large scale is responsible for the country’s terrible winter Air Quality, which is among the worse of Europe. Numbers in the map show PM2,5 concentrations around the country. See how dramatic the difference between the mainland and the islands is.

Unfortunately, despite the negative effects of wood smoke on people’s health with subsequent reduction of life longevity, there is no official discussion about the issue of wood burning. As such, 99,99% of Greeks remain completely ignorant about the serious harm they do to themselves and their neighbours, and hence they go on burning wood on such a massive scale without any restraint.

Health effects of breathing Wood Smoke

A recent, very important study conducted right here in Athens by Greek scientists of various national and international research institutes shows that wood smoke accounts for 43% (almost half!) of the annual carcinogenic potential of the city’s Air Pollution. 

This means that at least 43% of the cancer cases in Athens are due to wood smoke-related high PM levels. If you add traffic pollution to that, you have about 70% of the cancer cases in Athens due to totally avoidable reasons. Avoidable is the key word here, because if we suddenly decided to electrify heating and transportation in Athens, there would immediately be 70% less people dying of cancer in the city.

Isn’t this something that we ought to do, now that we know what Air Pollution does to us?

Particulate Matter PM2,5 concentrations in 30 Greek cities in three typical winter periods

Here below is a chart depicting the Particulate Matter PM2,5 concentrations found in 30 Greek cities in three typical winter moments.

The chart resumes very well how the weather conditions in winter are the main controllers of how high or low the Air Pollution is, all around the country. As a matter of fact, it is the weather that acts as the much blessed cleaner that can actually wipe off the pollution caused by man’s burning activities. Windy and rainy conditions clean up the air, while windless and humid conditions concentrate pollution to dangerous levels, especially in valleys and plains surrounded by mountains where the air can’t move around easily.

In the chart here below we can see very big differences in the Air Quality of various locations from around the country. We can also see how the wind is able to clean up the Air quite dramatically, but not everywhere. Some locations are more “blessed” than others in this respect. As we will see, Athens is one of those; by saying that we don’t actually mean that Athens has clean air, just that it is lucky that it is windier than other cities, otherwise it would fare much worse among the EU charts. We remind that among 1000 European cities, Athens is No. 71 from the bottom in terms of Particulate Matter PM2,5 pollution, which is a very bad score. And it is even worse for NO2 pollution, as it ranks No. 16 from the bottom!

PM2,5 concentrations in 30 Greek cities during two typical winter weeks. The three differ in that strong N and S winds blew on most of the Greek territory during the “Windy” week whereas a mix of windy and calm days characterized the “Mixed” week, and finally only weak, local winds blew during the “Calm” week.

More detailed Air Quality analyses for some chosen locations around the country

We describe here below the AQ for seven chosen locations from around the country. We separated the data for the two main seasons of the year: the colder season (01/10/20 – 30/04/21) and the following warmer season (01/05/21 – 30/09/21). The data are from the same periods for all locations, except for Agrinio whose AQ sensors have been installed later than the others (see here below). We also include the average AQ data for the whole 2021. Hence the results are shown for three periods: the yearly average, the warmer period and the colder period.

We show the data for each location with pie charts, which describe the percentage of the time that the Particulate Matter PM2,5 concentrations fell into the five AQ categories:

  1. Green category: PM2,5 0-5 μg/m3. Air is clean, no problems here!
  2. Yellow category: PM2,5 5-15 μg/m3. Air is clean, but not on the long term.
  3. Orange category: PM2,5 15-35 μg/m3. Air is moderately polluted. Be careful.
  4. Red category: PM2,5 35-75 μg/m3. Air is polluted. People should never have to breathe this pollution. On the long term this air is likely to cause illnesses.
  5. Purple category: PM2,5 >75 μg/m3. Air is severely polluted. Airmageddon! People who must breathe this kind of air on the long term will die sooner than others.

In the results here below we consider clean to relatively clean air the two first categories combined (green + yellow) and polluted air the other three categories combined (orange + red + purple).

The results are quite straight forward. The pie charts here below show quite obviously that:

  1. The pollution in winter is 2 to 5 times higher than in summer on the mainland, but not on the islands (more on that later) and in Vouliagmeni (which is only 20 km south of Athens);
  2. None of the locations have safe average levels of Air pollution over the entire year. Considering all the Greek locations where there are AQ sensor installed, the cleanest locations are the island of Skyros and the University of Patras, both with yearly averages of PM2,5 = 11,0 μg/m3, which are still more than double than the levels considered safe by the WHO (5 μg/m3). On the long term it is not safe to breathe these levels of Air Pollution.
  3. The most polluted locations are Agrinio, Skala Messinias and Ioannina, with PM2,5 yearly average concentrations of 29,8 μg/m3, 29,8 μg/m3 and 26,5 μg/m3 respectively (once a whole year of measuring will be covered for Agrinio too, it is likely that this location will pass 30 μg/m3, maybe even 35). These levels of pollution are 5 to 7 times the safety levels, which is not good at all for the people living there.
  4. Locations in the countryside enjoy better AQ than locations in cities (especially in the bigger cities) in the summer, but this is not the case in winter.
  5. Despite having half of the entire Greek population (i.e. a very large concentration of pollution sources), Athens has a better yearly average AQ than many smaller cities around the country.

1. Skala (Messinia)

Skala Messinias, as described in the introduction to this post, is plagued by wood smoke pollution in winter, as the charts above can confirm. On the evening of Nov 22, PM2,5 concentrations almost reached 1000 μg/m3, which is an exorbitant number! Se how PM2,5 goes into purple levels (>75 μg/m3) practically every single evening. And often, there is also smoke during the day when farmers burn the residuals from the olive collection in the fields.

As a result, in winter the air is in the purple level for 21% of the time, meaning that the inhabitants of Skala must breathe severely polluted air for practically 1/5 of the whole winter. Only for 7% of the time the AQ is within safety levels (<5 μg/m3).

Overall the Air of Skala is polluted for 66% of the time (aka two thirds), and clean to relatively clean only for 34% (or one third) of the time in winter.

The winter average PM2,5 concentration at Skala is 74,1 μg/m3, which is very, very bad!

2. Ioannina (Epirus)

Ioannina is a most beautiful city located on the shores of the Pamvotida lake on the Pindus mountains. Unfortunately, it is also the third most polluted location of Greece.

This is because the lake, surrounded by high mountains, is good recipes for fog in winter. What happens is that the high humidity generated by the lake condenses in the cold winter air which, in conditions of high atmospheric pressure with no wind, gets stuck above the lake and surrounding plain in a dense layer of fog, which covers also the city. Foggy conditions are very common in Ioannina in winter, and because most houses burn wood as a source of heat, the resulting smog (smog = smoke + fog) is a constant feature of the city, both at night and during the day.

Overall the Air of Ioannina is polluted for 74% of the time (aka three fourths), and clean to relatively clean only for 26% (or one fourth) of the time in winter.

Furthermore, the data show that only for 6% of the time in winter the AQ of Ioannina is within safety levels (<5 μg/m3) That’s really unacceptable!

The winter average PM2,5 concentration in Ioannina is 49,5 μg/m3, which is of course very high!

3. Nea Irakleio (Athens)

We chose Nea Iraklio as an example for Athens because it is one of the suburbs of the city that suffers the most from wood smoke pollution in winter.

Athens is a metropolis that was built in a big plain surrounded by mountains to the W, E and N, and by the sea to the south. Weather-like, it enjoys a very good climate because it is not humid like the W and N of Greece, and it has mild temperatures in winter. It gets hot in summer, mostly in July and August, but temperatures are more bearable than in Thessaloniki (the second-largest city of the country) for example, which has a much higher humidity.

The Athens plain is usually quite windy in winter, more than other locations in the mainland. This is a blessing because the wind helps the city to enjoying a better AQ than in many other Greek cities of the mainland, despite the fact that it is so big and has so many sources of Air Pollution. Nevertheless, the size of the city creates important disparities in relation to Air Quality, and the data show that the worst suburbs are up to three times more polluted than the cleanest.

The most polluted parts of Athens are the central (which has also the lowest elevation) and the northern parts of the plain, and Nea Irakleio lies practically within the junction of the two. Locations closer to Mt. Ymittos to the east of the city are by far the cleanest, as well as those further south by the sea. The western parts of Athens is not as clean, but better than the central part of the plain. Then there is the historical centre of Athens, which is a hilly part lying in-between the central part of the plain (polluted) and the Ymittos mountain (cleaner). In general it is cleaner but it is highly influenced by the polluted central part of the plain and less by the eastern, cleaner part near Mt. Ymittos. It is actually not so rare to witness pollution levels above 30-35 μg/m3 during windless, winter mornings on the W side of the Acropolis, while at the same time they are less than 7 μg/m3 in Plaka, literally just few hundreds meters away on the eastern side of the Acropolis! This is because the W side of the Acropolis hill is influenced by the air coming from the central plain which has accumulated big quantities of wood smoke during the night, while the eastern part of the hill has not.

As said above, Nea Irakleio is one of the most polluted areas of Athens in winter. Overall its Air is polluted for 69% of the time (about two thirds), and clean to relatively clean only for 31% (or one third) of the time.

The data show that also in Nea Irakleio, like in Ioannina, the AQ is within safety levels (<5 μg/m3) only for 6% of the time in winter. If you compare that with the cleanest part of the city (Vouliagmeni, see here below), which is not affected by wood smoke in winter and therefore has a score of 27%, you can see how much localized the problem of Air Pollution can be.

The winter average PM2,5 concentration of Nea Irakleio is 41,0 μg/m3, which is eight times the WHO recommended level of 5 μg/m3 and more than three times higher than the cleanest part of the city!

4. Thiseio (Athens)


Thiseio is a charming part of Athens’ historical centre lying right by the Acropolis, on its western side. As described above in the text about Nea Irakleio, Thiseio is a part of the historical centre influenced by the pollution generated in the central part of the Athens’ plain. Still, it enjoys a better AQ overall because it has less wood stoves and fireplaces. In fact many of the older and newer houses have natural gas as source of heat because historically this is the first part of the city that was connected to the old Athens gasworks factory (the “Gazi” gasworks factory was opened in 1857; it was closed in 1984 and it has now become a cultural and exhibition centre). Much of the pollution of Thiseio is actually generated by the many restaurants and bars of the area, as well as the polluted air that arrives from the central part of the Athens plain.

Overall the Air of Thiseio is polluted for 51% of the time (about half), and clean to relatively clean for 49% (another half) of the time in winter. Quite better than in Nea Iraklio, but still far from satisfactory.

“Only” 6% of the air falls into the purple (toxic) AQ category (see pie chart above) compared to the 13% of Nea Irakleio. The difference is quite big in the real world, because the smell of wood smoke is less intoxicating in Thiseio and remains in the air for less time at night compared to Nea Irakleio.

Furthermore, the data show that in Thiseio the AQ is within safety levels (<5 μg/m3) only for 14% of the time in winter. This is not as bad as in Nea Irakleio, but still it is far from being satisfactory.

In fact, and I say this out of experience because I live in Thiseio, at night we must keep the windows hermetically closed because of the wood smoke, without exception, if we don’t want to pollute to dangerous levels also the indoor Air. I actually have HEPA Air filters in every room of my house that help keeping the indoor AQ to safe levels (below 5 μg/m3). Without the filters I would never be able to enjoy clean air inside the house, because there is always some outdoor air that infiltrates one way or another into the house. Our neighbours sometimes have PM2,5 levels up to 40-50 μg/m3 INSIDE the house because they don’t mind the wood smoke smell they say, and don’t want to bother…! This is an attitude that I meet way too often, and it’s sad that people just don’t want to listen, especially when they have children that must live under those conditions for an entire winter, year after year.

The winter average PM2,5 concentration in Thiseio is 25,2 μg/m3, which is five times the WHO recommended level of 5 μg/m3 and two times higher than the cleanest part of the city, which is Vouliagmeni.

Above we included pie charts for Thiseio of the summer 2020 and also of the summer 2021 just to show the higher Air Pollution in 2021 due to the wildfires that took place in the N of Athens and on the Evia island in August 2021. Woos smoke covered the city for more than a week, and the its AQ was badly affected. The 2021 pie chart shows an increase of 10% of low AQ compared to the summer 2020.

5. Vouliagmeni (Athens)

Vouliagmeni is a sea side location only 20 km south of the centre of Athens. But Air Quality-wise, it looks as it was hundreds of km away, because it enjoys such a better AQ overall, one of the top three of Greece actually!

As seen in the charts above, it is striking how there are only few measurements that fall into the purple and red categories, and that the air pollution in winter is very similar to that of the summer. This is because there is practically no wood smoke in Vouliagmeni, and also very little smoke from other sources of heating (oil, gas, etc.). This happens because Vouliagmeni is a busy sea side of Athens in summer, but not in winter. Only a small percentage of the people who have a house there lives there also in the colder season.

Overall the Air of Vouliagmeni is polluted only for 30% of the time (one third), and clean to relatively clean for 70% (two thirds) of the time in winter. This is one of the best scores for the whole country. It doesn’t go better than that (but remember, we have data only for the Greek locations with AQ sensors; there are surely places in Greece with even better air…).

Vouliagmeni is also the location of Athens whose AQ falls the most into the green, safer category (<5 μg/m3), for 27% of the time. Only Ano Papagou and Cholargos comes close to that. All other areas of the city fall much shorter of that.

The winter average PM2,5 concentration in Vouliagmeni is 12,9 μg/m3, which is by far the cleanest part of the Athens area but still not satisfactory because it is two and a half times the WHO recommended safety level.

6. Tinos (Cyclades)

Tinos is a beautiful island of the Cyclades. It still has many inhabitants, a number of whom still farm and herd cattle, sheep and goats. Tourism has not altered its original character, fortunately.

The only PurpleAir AQ sensor of the island is located in the middle of the highest village of the island, Dyo Choria. There are no roads near the sensor, and in any case car traffic in the outside of the village is really limited, hence the sensor is never influenced by local traffic pollution (that’s why I placed it there). The only local pollution that can reach it might come from two or three wood stoves of the village (which are not close to the sensor anyway) and from the sporadic fires that farmers light up during the day to clean up their fields in winter. This sensor is therefore one of the only in Greece which mainly measures Air Pollution that is created further away and only in a minimal part locally.

Overall the Air of Tinos is polluted only for 33% of the time (one third), and clean to relatively clean for 67% (two thirds) of the time in winter. For another 22% of the time the AQ is within safety levels (<5 μg/m3), which is one of the best scores in the country.

The winter average PM2,5 concentration in Tinos is 13,0 μg/m3, which again shows that it is one the top cleanest locations of Greece. Still, this is not satisfactory because it is two and a half times the recommended safety level of 5 μg/m3 .

It is not surprising that Tinos is one of the cleanest locations of the country. Yet, it looks as if the absence of traffic pollution and the very low presence of wood smoke are not enough in order to enjoy a perfectly clean air to breathe in winter. There is much Air Pollution that travels far from their source, and it is clear that the islands of the Aegean are not safe from that, even if there is a wide sea that separates them from large cities and other pollution sources.

7. Agrinio (W Greece)

The last example that we want to describe is the city of Agrinio in W Greece, which is the new “bad guy in town”. Its PurpleAir sensors were installed only in May 2021, hence there are no data for the whole of 2021 in order to make a comparison with other Greek locations. Nevertheless, we were able to analyse the data for the warmer period of 2021 (14/05/21 – 15/10/21), and for the first two colder months of the following winter (01/11/21 – 31/12/21).

The data of the months November and December 2021 are quite shocking.

The average PM2,5 concentration of the two months combined is 79,6 μg/m3, which is in the purple category, and hence it is highly toxic! New Year’s week alone had an average of 108,3 μg/m3!

And, overall, the winter Air of Agrinio is polluted for as much as 81% of the time, and clean to relatively clean only for 19% of the time!

This is as bad as it can be; the PM2,5 concentrations reach 350 to 400 μg/m3 every single night, and the air is in the purple category for as much as 30% of the time, meaning that the inhabitants of Agrinio must breathe severely polluted air for practically 1/3 of the whole winter. That’s apocalyptic! And if we look at the several PurpleAir sensors of the city we can see that this problem is generalized in the whole town, not only a local issue.

To make things worse, the data show that only for 2% of the time in winter the AQ of Agrinio is within safety levels (<5 μg/m3) People can’t really know what fresh, clean air smell in that city in winter! That’s awful. And in the summer it’s again only 10%, for other reasons.

Even more worrying is that the PurpleAir sensor from which we took the data is located at the 17th elementary school of the city. How is it possible to let children breathe such a toxic air, for a whole winter season, year after year?????

Why is this happening in Agrinio, why does it have such a bad Air Quality? Because people burn wood for heating up their houses on a massive scale. Most people have fields from which they get their own wood, which more often than not is burnt still moist. And surely they don’t use “eco” stoves (which are bad anyway), but old types, like those of our grandpa. The city is also located within a plain surrounded by mountains (like Ioannina, another Air Pollution champion) in which there are several lakes (although not directly near the city). Furthermore in winter there is not much wind, hence the moist, polluted air stagnates over the city.

Hopefully the municipality will use the PurpleAir AQ data to draw their own conclusions and start dealing with the problem…

The above data show that there is a serious issue of bad Air Quality in Greece in winter, which is mostly due to the heavy use of wood as a source of heating.

Smoke at night in the central part of the Athens plain, which is the most polluted area of the city along with the northern suburbs.

Wood smoke from stoves and fireplaces combined with the heavy traffic in the big cities (which is made up by around 50% of older, polluting vehicles) and the traditional burning of agricultural residuals in the fields heavily pollute the air of the whole country, both in the larger and smaller cities and in the countryside. There is no place in the country (except for higher up on the mountains) where the Air Quality meets the safety standards recommended by the World Health Organization (WHO). In fact, even the cleanest locations of Greece have PM2,5 concentrations that are 2,5 times higher than that – while the worse locations are almost 20 times that number…

It’s about time that the Greek authorities (local and national) started campaigns that aim at informing the population about the health problems connected to Air Pollution. And at the same time they must start to seriously working at cleaning up the air we breathe. So many deaths would be avoided by doing that.

WOOD BURNING MUST BE BANNED, starting from densely populated cities. Agrinio and Ioannina should be the first cities to do so!

Published by cleanairingreece

CleanAir in Greece is an independent site meant to inform the public about the day to day Air Quality in Greece, with advice on how to protect ourselves from the dangers of Air Pollution

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