Global NEST Journal

The greater area comprising the Attica peninsula and the Saronic Gulf is greatly influenced by various
local circulation types. During winter months, moderately high air pollutants concentrations are
observed when the prevailing condition is either stagnant or a weak southern flow. The case studied in
this paper regards an episode that occurred in mid-December. This episode is characterized by very
weak pressure gradient over Greece, and very little change in wind speed and direction with height,
without the precedence of exceptionally strong warm advection in the lower troposphere during the
days before the episode. This episode was not characterized by very high air pollution values, a rather
common feature during December, that even though it presents one of the highest episode frequencies,
the observed values are not high enough to require the enforcement of restrictive measures.

Chlorination of drinking water leads to the formation of a variety of Disinfection By-Products (DBPs) that may have adverse health effects on humans. Research on this subject has been continued and new epidemiological and toxicological studies have been conducted. This review summarizes factors affecting DBP formation and predictive equations proposed for it, physical and chemical properties, environmental fate, actual measurements of these compounds and technologies for controlling them, as well as regulation and currently proposed changes of their Maximum Contaminant Levels (MCLs) after evaluation by EPA of new data available.

A climatological analysis of atmospheric concentrations of primary air pollutants in Athens, Greece, is
presented for the 11-year period 1987-1997, since the automated local air pollution network operating
by the Ministry of Environment started to record all conventional pollutants. The concentration levels
of the atmospheric pollutants carbon monoxide, nitrogen oxides, sulfur dioxide and black smoke for the
most polluted stations (Patission, Athinas and Piraeus) of the air pollution network were examined. For
all primary pollutants a seasonal variation with minimum in summer and maximum in winter is
observed. Sulfur dioxide has the strongest seasonal cycle and black smoke the weakest. There is a significant
downward trend for almost all pollutants in all stations. The highest reductions are observed in
Patission where a comparison between the 3-year periods 1988-1990 and 1995-1997 gives 52%, 34%,
26% and 20% decreases for sulfur dioxide, carbon monoxide, nitrogen oxides and black smoke, respectively.
The pollution abatement measures taken by the state authorities during the period 1990-1994,
mainly consisting in the replacement of the old technology gasoline-powered private cars and the
reduction of the sulfur content in diesel oil, seem to be the primary cause of the improvement in air quality in Athens during the recent years.

This paper deals with the analysis of atmospheric concentrations of secondary photochemical air pollutants
in Athens for the 11-year period 1987-1997. Photochemical pollution, which seems to be the
most serious air pollution problem in Athens, is originating mainly from the transformation of car
emissions, and its control is a quite complicated task since various non-linear phenomena are implicated.
The main subject of this work is to examine whether the substantial decrease observed in the
concentrations of the primary air pollutants, especially for CO, in Athens in recent years is followed by
a corresponding decrease in the photochemical air pollutant levels in the Athens basin, while the characteristics
of the seasonal and diurnal profiles of photochemical pollution are investigated. In this context,
the interannual variability of O3 and OX (O3 + NO2) is examined for the peripheral stations of
Liossia (10 km northwest from city center) and Smyrni (5 km southeast), which have continuous
records of O3 and NO2 data since 1987. In general, the concentrations of the photochemical pollutants
(especially OX) in both examined stations are comparable, while they seem to have remained essentially
at the same levels since 1990. Further pollution abatement measures should be taken in order to
comply with the EU ozone air pollution standards in the Athens basin.