Atmospheric Pollution – Part I: The problem of Atmospheric Pollution in Urban Areas.

Peter Essick, National Geographic

Pollution is any undesirable change in the physical, chemical or biological characteristics of air, soil or seas which adversely affects both flora and fauna of the planet. Air pollution is creating due to the accession of any material, molecular or particulate, to the atmosphere that surrounds us. This unnecessary influx of materials results in short or long-term pollution of life on Earth. Air pollutants are considered to be any material that may enter in it – through deliberate or unintentional processes – creating direct or indirect harmful influence on the organisms. Pollutants include specific chemicals and various forms of energy such as heat, sounds and radiation.

Under certain circumstances, air pollution is likely to reach levels that create unhealthy living conditions, so, it is necessary in this article to introduce the main sources of pollution and the harmful pollutants. In addition, it is important to explain how this situation is formed in the various urban centers of our country – especially in Attica – in order to realize the scope of the problem.

In modern times, the problem of atmospheric pollution is largely due to the anthropogenic factor. The main sources of air pollution due to human activities are: means of transport, domestic heating, electricity generation, unwanted combustion and generally industrial emissions. It is difficult to determine precisely the percentage of participation of each source in the general pollution problem, as our society is constantly evolving, so the contribution rates cannot be stable.

Image Source: Getty Images

Image Source: Getty Images

 

When we deal with the issue of air pollution, we usually refer to seven main groups of pollutants [Ref.1: Atmospheric Pollution, Ioannis Gentekakis, 2010]:

  1. carbon-containing compounds: such as carbon dioxide and carbon monoxide (CO2 & CO), hydrocarbons and their derivatives (H/Cs), methane (CH4) and volatile organic compounds (VOCs).
  2. nitrogen-containing compounds: such as nitrous oxide (Ν2Ο), nitrogen oxide and dioxide (ΝΟ & ΝΟ2), ammonia (ΝΗ3) and reactive nitrogen (ΝΟy).
  3. sulfur-containing compounds: such as sulfur dioxide (SO2), hydrogen sulfide (Η2S), ΟCS / carbonyl sulfide, dimethyl sulfide, CH3SCH3, DMS.
  4. halogen-containing compounds: such as the known halogen gases (CL2, F2, Br2) and hydrogen halides (HCl, HBr, HF) and the halogenated hydrocarbons which consist the basis of insecticides and herbicides, refrigerants or freons, fire extinguishers, sprays and cleansing / disinfecting agents.
  5. photochemical oxidants: which are the result of a series of complex atmospheric reactions that occur when active organic substances and oxides of nitrogen (NOx) accumulate in the atmosphere and are exposed to sunlight.
  6. particulate pollutants & aerosols: where particulate pollutants are all those non-gaseous substances in the atmosphere, and may include ions, molecule complexes, ice crystals, dust, tobacco particles, raindrops, pollen etc. which evolve into the atmosphere through various mechanisms.
  7. hazardous air pollutants, air toxics: a category of pollutants that are directly responsible for increasing mortality, or causing serious illnesses, or endanger human health, for example: alkyllated lead compounds, mercury and others.

 

Some of the substances, that are mentioned above, enter into the atmosphere directly after their emission from the source (primary pollutants), while others, considering the atmosphere as a large reactor, arise after some processes (secondary pollutants). The Environmental Sciences are extensively involved in the sources, appearance and impact of pollutants, so for more information you can refer to the literature at the end of the article, and this is generally a part of the topic “Atmospheric Pollution” that could not be confined to a single article.

Greece continues to face environmental problems and challenges. The main problems are in the control of emissions to the atmosphere from road transport, industrial enterprises and the extraction of large lignite (for electricity). In the large urban centers of our country (Athens, Thessaloniki, Patras, Heraklion, etc.), there have been identified mainly two types of atmospheric pollution that have been recognized for many years: high concentrations of PM and photochemical cloud, that is associated with nitrogen oxides (NOx), sulfur dioxide (SO2), smoke, hydrocarbons (HC) and carbon monoxide (CO) (which are primary pollutants) and the presence of various secondary pollutants, as a result of a series of chemical reactions caused by sunlight [2].

In particular, in the past decades, Athens experienced the yellow-brown photochemical smog that was a mixture of tobacco particles, carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxides (NOx) and ozone (O3) mainly internal combustion engines, central heating and exhaust gases from industries and crafts. However, over the years and in addition with the imposition of changes such as fuel improvement and vehicle replacement, the upgraded environmental legislation in order to restrict pollutants from crafts and industries, the relocation to industrial areas, and the import of natural gas as an energy fuel, have led to the gradual improvement of air quality in major cities.

We could admit that the condition of the atmosphere of major cities had a positive development until the appearance of the financial crisis in our country. The 2010-2017 crisis, that connected to the forthcoming increase in heating oil tax, is directly linked to the increase in photochemical pollutants (O3) and particulate matter (PM), despite the fact that in recent years it has declined air pollution with regard to the SO2, NOx, CO and exceedance of the alert thresholds of the concentrations of the different pollutants are less frequent than in the past. This means that the problem of air pollution is multidimensional, continuous, and we must approach it every time from a different perspective so that it can understood and eventually, resolved.

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Bolonaki Evropi,

Physicist – Physical Oceanographer

 

References

[1] «Ατμοσφαιρική Ρύπανση: επιπτώσεις, έλεγχος & εναλλακτικές τεχνολογίες- 2η έκδοση», Ιωάννης Γεντεκάκης, Publications: Κλειδάριθμος, 2010.

[2] «Atmospheric Pollution in Urban Areas of Greece and Economic Crisis.  Trends in air quality and atmospheric pollution data, research and adverse health effects», Valavanidis Athanasios, Thomais Vlachogianni, Spyridon Loridas, Constantinos Fiotakis, Department of Chemistry, University of Athens, University Campus Zografou, 15784 Athens, Greece, 20/11/2015, link: http://www.chem.uoa.gr/?p=6294

[3] «Οικολογία: Εισαγωγή στη Μελέτη του Περιβάλλοντος», Dr. Ν.Σ. Χριστοδουλάκης, Publications: Πατάκη.

 

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