Athens Air Quality Journal

We start this month a journal whose aim is to picture the daily Air Quality (AQ) in Athens.

This post aims at documenting how the atmosphere looks and feels like in terms of Air Pollution, day after day, in our capital. Photographs taken from Filoppapou Hill show the visibility over the city, which is a way of visually depicting how clean the Air is, while a screenshot from an AtmoTube PRO portable AQ Monitor (made at the moment the picture(s) were taken), as well as from our own Purple Air Monitor located in Thiseio, show in real time an Air Quality Score based on the Particulate Matter (PM) concentration in the Air.

The World Health Organization (WHO) updated and tightened the Air Quality recommendations at the end of September 2021, which had not been updated since 2005. During these past 16 years a whole lot of evidence has been collected in thousands of scientific studies that show how Air Pollution is the biggest environmental threat to our lives, which kills up to 8 million people every year (over 16.000 in Greece alone). Nine people in 10 breathe polluted air worldwide.

The new WHO AQ recommendations are the following:

The major concern for the people of Athens are Particulate Matter (especially PM2,5 but also PM10), Ozone (O3) and NO2. All these pollutants are very high at times in Athens compared to other EU cities.

PM2,5 is particularly dangerous because it goes straight into our lungs with every breath we take and from there it passes through into our blood stream, from which it then reaches every organ of the body, leading to a general state of inflammation and to all sorts of related illnesses. Ozone and NO2 are highly reactive gases that oxidise (literally “burn”) cells in our respiratory ways and lead to various serious illnesses, such as asthma, etc. See here more info on these pollutants.


22-23/10/2021

AQ score = 67-91. Air Pollution is fairly high in the morning and low during the day. NO2 and O3 are high.

These couple of days the Air Quality in Athens has improved thanks to the S wind, which blew away pollutants and brought temperatures of up to 25 degrees in the afternoon. These are like nice, spring days! We woke up with low levels of PM2,5 (around 8 μg/m3), which temporarily increased to 30 μg/m3 at 9:00AM until 10:30-11:00AM. Then the S wind started and the Air Quality quickly improved to good levels.

This phenomenon with a sudden Air Pollution increase in the early morning is something that happens daily since last week. It’s due to two factors: 1. to the morning traffic rush hour but 2. especially to the warming up of the atmosphere by the sun around 1 hour after sunrise. The warmer, humid air raises and brings along the pollutants that were deposited to the ground as the air cooled during the previous night. The effect is quite impressive, considering that this morning we had a very nice, crispy air at sunrise, but only 1 hour afterwards it worsened by a 4X factor and the smell of dirty air became very obvious. Then as quickly as the phenomenon came, it went away after about 1 hour and the air became clean again for the rest of the day (and evening).

Air Quality week of 17/10/21 – 23/10/21 in Thiseio, Athens showing the sudden increase and decrease of Air Pollution in the morning these days

PM2,5 levels range from 7 to 30 μg/m3, which are half and double the limits of the new WHO recommendation for a 24h exposure.
NO2 was 60-80 μg/m3, which is around three times the recommended level for a 24h exposure.
O3 reached 104 μg/m3, which is above the WHO recommended level for a 8h exposure.

Today we can open our windows for longer periods of time after 11:00AM.


21/10/2021

AQ score = 57-79. Air Pollution is high at night and in the morning and somehow lower (but not good) only during the warmest hours of the day. NO2 and O3 are high. Sensitive people might start feeling some throat irritation and coughing when exposed to these levels of Air Pollution.

Today the Air Quality in Athens has worsened even further. We woke up with levels of PM2,5 at around 30 μg/m3, which increased to 40 μg/m3 due to high vehicle traffic at rush hour until around 11:00. The air was very “heavy” and bad smelling this morning and only after the wind managed to blow away some of the pollution it became better.

As mentioned earlier (see 18-19/10/2021), this is the beginning of the winter “Airmageddon” in Athens (and in Greece in general). This pattern of (very) high air pollution in the night and morning will be the “normal” for the next 51/2-6 months, until mid/end April. The only moments when the air will be less polluted will be when winds will blow strong either from the north or the south. From now on Athens will, once again, be one of the most polluted cities in the whole of Europe.

If we want to be serious about reducing the serious negative impact of Air Pollution on our personal (and of our dear ones) health this coming winter, we should consider at least taking a few measures:

  • Check out the website Purpleair.com often, which shows in real time the Air Pollution in Athens but also allover the world. This site will immediately show you what kind of air we have in the city at any time;
  • Wear N95 masks also outdoors, because they protect also from PM2,5 from traffic and wood smoke pollution, not only from viruses. Wear them especially when walking on busy roads and when you sense the smell of wood smoke in the air;
  • Carefully ventilate your home by opening windows only during the time of the day when outdoor air pollution is at its lowest. Surely don’t open windows at night and in the morning before 10:30 AM. Best time to open them is from 11:30 to sunset. Some days you can open them more often, and some days you should never open them. Again, check out the Purpleair.com website to see what’s best to do.
  • If you do sport activities in the city, you should follow the same principle as with window opening. Jogging in the early morning or at night with high outdoor Air Pollution is very unhealthy! Try to find time during the afternoon for that. Surely, doing physical activities is better for our health than sitting all day on a chair, but doing sports while breathing high Air Pollution is putting you in more danger than staying at home. See an article about physical activity in polluted areas here;
  • Protect your children from Air Pollution!
PM2,5 levels range from 17 to 40 μg/m3, which is up to almost 3x the limits of the new WHO recommendation for a 24h exposure.
NO2 was 60-80 μg/m3, which is around three times the recommended level for a 24h exposure.
O3 reached 110 μg/m3, which is above the WHO recommended level for a 8h exposure.

Today we should not open our windows for longer periods of time. Surely avoid opening them during the morning and at night. Consider using indoor air filters to keep the air in your home at safe, clean levels.

The same applies to outdoor exercise. Avoid exercising in the morning before the wind kicks in and at night. Children should not be allowed to play outdoors with these levels of Air Pollution.


20/10/2021

AQ score = 67-85. Air Pollution begins to be high at night and in the morning and somehow lower only during the warmest hours of the day. NO2 and O3 are high. Sensitive people might start feeling uneasy when exposed to these levels of Air Pollution.

Today the Air Quality in Athens has worsened again. We woke up with levels of PM2,5 at around 20 μg/m3, which increased to 30 μg/m3 due to high vehicle traffic until around 12:00. Only then a low wind started to clean the air to levels of around 12 μg/m3.

Beside local pollution sources, there is also an influx of Particulate Matter in the atmosphere from further away than Greece. Along with a higher air pressure, the result is that today the air feels “heavy”, and those who can discern it, can feel the typical persistent bad air smell that was much less obvious all the previous windy days. Many people in the city surely felt the “heaviness” of the air and had headache today, without knowing why.

PM2,5 levels range from 12 to 30 μg/m3, which is up to 2x the limits of the new WHO recommendation for a 24h exposure.
NO2 was 50-70 μg/m3, which is two to three times the recommended level for a 24h exposure.
O3 reached 120 μg/m3 during the warmest hours, which is above the WHO recommended level for a 8h exposure.

Today we should open our windows for a longer period of time only during the afternoon hours. Surely avoid it during the morning and at night.

The same applies to outdoor exercise. Avoid exercising in the morning before the wind kicks in and at night.


18-19/10/2021

AQ score = 77-91. Air Pollution is above safety levels at night and in the morning and low only during the warmest hours of the day. NO2 and O3 are high.

After the “Ballos” storm has receded, the weather became more stable. Temperatures dropped a few degrees both during the day and night, humidity decreased and the atmospheric pressure rose. This is a prelude to the typical, more stable, sunny weather in Athens that is met during many days in winter. High pressure means that there is low air circulation; often, during the early morning hours, there is actually a temperature inversion, in which the 250m air layer close to the ground is still colder than the air above (due to quick soil heat loss of the previous clear sky night). This colder air is heavier and remains near the ground trapping all the air pollutants from the early traffic hours and from the previous night’s residential heating. Only after the sun has ascended enough to be able to warm up the cold air layer the air pollutants start then to disperse upwards, usually after around 10-11:00AM.

Needless to say, this more stable colder weather that traps pollutants in the city is no good news: from today officially start the “Airmageddon” in Athens. Unfortunately these days will last until mid/end April. The only moments when the air will be less polluted will be when winds will blow strong either from the north or the south. From now on Athens will, once again, be one of the most polluted cities in the whole of Europe.

PM2,5 levels range from 7 to 20 μg/m3, which begins to be above the limits of the new WHO recommendation for a 24h exposure
NO2 was these day between 50-70 μg/m3, which is two to three times the recommended level for a 24h exposure.
O3 reached 120 μg/m3, which is above the WHO recommended level for a 8h exposure.

These days we should open our windows for a longer period of time only during the afternoon hours when the air is clean. Surely avoid it during rush hours and at night.


14-17/10/2021

AQ score = 90-96. Air Pollution is low during both day and night and poses no serious threat to our health. NO2 is high.

These couple of days, the “Ballos” storm has been pouring down huge amounts of rain allover the country. Athens has been flooded, as well as many villages. The rain gauge on our roof in Thiseio measured a record of 159mm of rain per day on the 14th, which I had never seen before. Imagine that Athens has an average of 420mm/year, so around the 40% of that rain fell in one day alone.

Temperatures in Athens are still mild, and no heating has been turned on yet. The result, along with the storm’s “cleaning” action, is that the Air Quality in the city is very good, both during the day and at night.

PM2,5 levels range from 7 to 12 μg/m3, which is around the limits of the new WHO recommendation for a 24h exposure.
NO2 was 50-70 μg/m3, which is two to three times the recommended level for a 24h exposure.
O3 reached 80 μg/m3, which is above the WHO recommended level for a 8h exposure.

These days we can open our windows with little concern, both during the day and at night.

Video of the streams created by the pouring rain on Pnika Hill

10-13/10/2021

AQ score = 70-98. Particulate Air Pollution is within safe limits during the day and poses no serious threat to our health. But NO2 is high. At night Air Pollution is above the WHO limits.

These days, the Air Quality of Athens is relatively good. The weather is still humid and rainy, with a S-SW wind that blows away the Air Pollution generated in the city during the day. At night the wind ceases to blow and Air Pollution builds up, more so in central Athens and less in the periphery.

PM2,5 ranges from 3 to 12 μg/m3 during the day, which is at the limit of the new WHO recommendation for a 24h exposure and up to 25-30 μg/m3 at night, which is above the WHO limits.
NO2 is 60-70 μg/m3, which is more than three times the recommended level for a 24h exposure.
O3 reaches 90 μg/m3, which is within the WHO recommended level for a 8h exposure.

These days we can open our windows with little concern during the day but we should close them after 20:00 PM until the next morning.


09/10/2021

AQ score = 81-92. Particulate Air Pollution is within safe limits and poses no serious threat to our health. But NO2 and O3 are high.

Today, the Air Quality of Athens in the morning was similar to the one of yesterday, but after 14:00 PM it improved to very good levels. It did not rain today, but the weather was still very humid. The light S-SW wind and the warming of the atmosphere began dissolving the humidity and blowing away the air pollutants in the afternoon.

Yesterday’s rain was a blessing for the natural habitats of Athens. Apart from a little rain at the beginning of September, it hadn’t rained for over 4 months, and the extended, extreme heat of this summer put all plants and animals of Attica under big stress. See here below how dry the Olive trees, Aleppo pines and Carob trees around the Acropolis are right now. The leaves have all dried up and the trees are yellow instead of green. Many trees have actually died this summer. This is how desertification starts: the vegetation, put under severe stress by record heat and lack of rainwater, simply can’t cope anymore and dies. First to go are the trees, then the shrubs, until only the hardiest of plants will remain to withstand the new climate extremes.


At 9:00 AM in central Athens:

PM2,5 was 15 μg/m3, which is at the limit of the new WHO recommendation for a 24h exposure.
NO2 was 70 μg/m3, which is more than three times the recommended level for a 24h exposure.
O3 was 90 μg/m3, which is within the WHO recommended level for a 8h exposure.

After 14:00 PM:

PM2,5 was around 6 μg/m3, which is within the new WHO limits for a 24h exposure.
NO2 was 77 μg/m3, which is more than three times the recommended level for a 24h exposure.
O3 was 130 μg/m3, which is above the WHO recommended level for a 8h exposure.

08/10/2021

AQ score = 81. Particulate Air Pollution is close to the safe limits and poses no serious threat to our health. But NO2 is too high.

The day started in a gorgeous way today…

Today, the weather has changed and with it also the Air Quality of Athens. The N-NE wind of the past week stopped blowing, big clouds came in and rain started pouring down, at last. A light S-SW wind is now bringing humid, warmer air to the city, and this weather will remain similar for the next several days. The Air Quality is reduced now because the light wind is not enough to blow the city’s Air Pollution away and the high humidity “traps” the air pollutants in the air. When the rain pours down it clears the pollution away fortunately, but the tendency is in general to have higher pollution compared to last week. We should be concerned especially in the areas of the city that have high car traffic. For example, while on Philoppapou Hill PM2,5 was 17 μg/m3 at noon, just 10 minutes later in Syntagma Square it was 28 μg/m3, which is not good.

At noon in central Athens:

PM2,5 is around 17 μg/m3, which is just above the new WHO limits for a 24h exposure.
NO2 is 82 μg/m3, which is more than three times the recommended level for a 24h exposure.
O3 is 23 μg/m3, which is within the WHO recommended level for a 8h exposure.

Today we should open our windows with some concern and not leave them open for too long, especially if we are close to a busy road.


07/10/2021

AQ score = 97. Air Pollution is low and poses no threat, but NO2 is high.

Today, like during the whole past week, with and AQ Score over 90 the Air Quality of Athens is excellent thanks to the N-NE wind that is still blowing day and night. The wind is constantly pushing the traffic fumes and other sources of air pollution away, while domestic heating has not been started and therefore there is no Wood Smoke in the city yet. As a result the Air is generally clean in the whole city (with the exception of localized situations like close to the main traffic arteries for example). The visibility is excellent and from the Filoppapou Hill it is possible to see more than 20 Km away in all directions.

At noon in central Athens:

PM2,5 is around 5 μg/m3, which is excellent also under the new WHO limits.
NO2 is 60 μg/m3, which is more than twice the recommended level for a 24h exposure.
O3 is 80 μg/m3, which is within the WHO recommended level for a 8h exposure.

Today it is one of those (rare) days in Athens in which you can keep your windows open without being too much worried about putting your health at risk.


06/10/2021

AQ score = 94


05/10/2021

AQ score = 90


04/10/2021

AQ score = 92


03/10/2021

AQ score = 95


02/10/2021

AQ score = 92


01/10/2021

AQ score = 94

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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