Athens has become known for poor air quality. During the city's frequent severe incidents of nephos (smog), many citizens require medical care for circulatory and respiratory ailments. Athens's climatic conditions favor formation of photochemicals that trap pollutants close to the ground, partly because the reconstruction activity that began after World War II has proceeded without a comprehensive plan for traffic and industrial location. The same conditions contribute to air pollution in Thessaloniki, but to a lesser degree. More than half the total vehicles in Greece are in the Athens and Thessaloniki areas, and their number doubled between 1983 and 1992.
Sulfur dioxide, contributed chiefly by industrial effluents, has severely damaged stone buildings and monuments in Athens and Thessaloniki and generated acid rain that has caused some deterioration to forests in Epirus, Macedonia, Central Greece, and around Delphi, east of Athens. According to estimates, the Parthenon, the best-known of Greece's remaining architectural monuments from classical times, has sustained more atmospheric damage since 1970 than it did in its first 2,000 years of existence.
The largest single source of sulfur dioxide pollution, the oilburning electric power station in the industrial center southwest of Athens, was closed in 1994 except for emergency power supply. Other heavy polluters are the chemical, textile, and nonmetallic mineral industries established in the Athens region during the boom of the 1970s. Fuels used by Greek industries generally have a slightly higher sulfur and lead content than those used in other European countries, but central heating plants use high-sulfur oil. Winds also transport sulfur dioxide from industrial centers in neighboring countries. Air quality over the major Greek islands has remained good, except for a few population centers such as Heraklion on Crete.
Water pollution has likewise become a serious problem because of industrialization and development policies. Greece has shared in the general deterioration of water quality in the Mediterranean Sea in recent decades. In addition, Greece has drained many lakes completely to generate hydroelectric power or to expand agricultural land. Several animal species have disappeared from Greece as a result of habitat alteration caused by this process. An extended drought (1987-93) diminished both water quantity and water quality in rivers and lakes, causing chronic water shortages in the largest cities and limiting the growth of natural vegetation. Harbors and lakes adjacent to industrial centers, especially the Gulf of Saronikos south of Athens, upon which about half of Greece's industry is located, receive large quantities of untreated industrial waste and municipal sewage. Experts describe the inner gulf as nearly devoid of life. The same type of urban pollution occurs in Thessaloniki's Gulf of Thermaikos. Altogether, about fifty urban centers deposit sewage into the seas surrounding Greece. Ships pump out their bilges and oil as well. In 1994 only 10 percent of the Greek population was served by waste-water treatment plants and, in spite of Greece's extensive coastline, it produced only 0.1 percent of the world's catch of fish.
Since 1970 drastic increases in agricultural application of chemical fertilizers and pesticides have added a new source of runoff pollution. Rivers farther from industrial regions have remained relatively clean, but the diversion of the Akheloos River for hydroelectric power generation in the southwest corner of the mainland was expected to have a drastic ecological effect beginning in the 1990s.
Greece's soil, naturally poor in organic matter, has been degraded further by uncontrolled use of fertilizers and by soil erosion. (Erosion is hardly a new problem, however--Plato described the erosion of Greece's hills 2,400 years ago.) Together with chronic droughts, erosion has caused accelerating desertification in many agricultural areas . Vegetation has also been stripped by overgrazing and the clearing of steep slopes for construction projects. About one-third of Greece's irrigated farmland suffers from saline deposits. The agricultural fields of Thessaly and Macedonia, on the other hand, do not have salinization or erosion problems.