Rising summer temperatures have made air conditioners so popular that Greeks bought 400,000 of them in 2000. Greece is the third-largest buyer of a/c units in Europe, after Italy and Spain. But continuous use of air conditioning is a health hazard. Poorly maintained and improperly used air conditioners can cause respiratory infections, colds and chills. The cooling systems used in large buildings may harbor Legionella pneumophila – the microbe that causes the deadly legionnaire’s disease. «The accumulation of foreign particles or microbes in the small a/c units people use at home can upset the human respiratory system,» explains lung specialist Giorgios Varouchakis. «But if the filters are cleaned regularly and the machines are used sensibly, there’s no danger.» In heavily polluted downtown Athens, a/c filters need cleaning twice as often as in other areas. Yet even when air conditioning is used sensibly, individuals who are prone to infections of the upper respiratory tract, allergic rhinitis and similar ailments should avoid prolonged exposure to air conditioning. The temperature of a/c units should always be regulated so that there is not a great disparity between the internal and external environment – as a general rule, no more than 5 degrees Celsius (41 Farenheit). Increasingly hot summers have boosted sales of a/c units. According to ICAP pollsters, Greeks spent around 187.7 million euros on air conditioners in 1997, rising to 328.4 million euros in 2000. Whereas in 1994 Greeks bought just 116,000 a/c units, in 2000 they bought 409,000, an increase of 350 percent. The steepest increase was in 1998-99 (47 percent). Air-conditioning units in homes are easily maintained by their owners; but units in larger areas such as company premises, hotels and hospitals are not always kept clean. Crowds, smoke and antiquated air conditioning spoil the air and create the conditions in which microbes develop. As Varouchakis says: «If large water-operated cooling systems are not properly cleaned and chlorinated, then bacteria can develop, the most dangerous being Legionella pneumophila.» ICAP figures show that 24.9 million euros were spent on large a/c units in 1997, rising to 35.2 million euros in 2000. From 3,000 sold in 1994, the number rose to 4,400 in 2000, an average annual rise of 6.59 percent in seven years. Sales of fan coils, which are used in large buildings, rose from 28,5000 in 1994 to 43,2000 in 2000. Air conditioning has become standard household equipment, but as Varouchakis points out, we should not keep it running 24 hours a day.