Summary:
The scope of this dissertation is to study the spatial and temporal distribution of the levels to photochemical pollution in the Attica Basin, as well as to interpret the variability and trends of monthly values for all years. The data derive from the measurements of air pollutants of the National Air Pollution Monitoring Network, under the Ministry of Environment and Energy, which operates 14 air pollution measurement stations in greater Athens area.
Data on the available photochemical pollutants of nitric oxide (NO), nitrogen dioxide (NO2), and ozone (O3) were therefore processed in the period 1984–2017 for the ATH, ARI, GEO, MAR, LYK, LIO, PIR, PER, SMY, and PAT stations. In particular, the diagrams of the monthly concentrations of photochemical pollutants were created, where hourly variations are studied during the 24 hours for the above stations. The monthly averages of the concentrations of photochemical pollutants, as well as their monthly trends along with their statistical significance, were also calculated for each station for the examined period.
The results show that the highest concentrations of nitric oxide NO pollutant occur in the
winter months because the use of central heating and chimneys of buildings prevail in these months and the increased use of transportation from workers. In terms of hourly variations, we find that maximum concentrations prevail in the morning hours between 8:00-10:00 and during the evening between 21:00-23:00 due to the intense traffic. The stations with the maximum concentration of NO are ARI, ATH, MAR, GEO, PAR, and PIR because they belong to the category of urban and industrial stations. From the NO temporal variations, we find that the higher values occur mainly until 2010, while the values of the maximum concentrations decrease thereafter, which is due to the technological upgrade of old cars.
For NO2 pollutant, the maximum concentrations are found for most stations in the summer months, while at the stations LIO, LYK, and MAR the maximum values appear in the winter months. With regard to hourly values, a maximum is presented between the hours 10:00-12:00 and 22:00-24:00. The stations with the highest values of NO2 are ARI, ATH, PAT, and PIR, because they are affected by urban traffic. Concentrations peaked in the years 1984-2008 due to old fuels.
O3 exhibits the maximum monthly values in the summer months due to increased sunshine
intensity and duration, and maximum hourly concentrations shortly after noon. The stations with the highest concentrations of ozone are in the northern suburbs, LIO, LYK, and MAR, which is attributed to the phenomenon of sea breeze.
It is important to note that all three pollutants and mainly the nitrogen oxides exhibit
statistically significant decreasing trends in the entire examined period, which can be mainly attributed to the new pollution control technologies.
Keywords:
Air pollution, photochemical smog, ozon, ozone layer, acidification, photochemical pollutants, ozone hole, ultraviolet radiation
