Deafness, high blood pressure, headaches and disturbed sleep are some of the ill effects that noise has on health. Nikos Maroudias, director of the ORL department at Aghia Olga Hospital told Kathimerini: «Up-to-date studies in industrialized countries have shown that the effects of noise on the cardiovascular system, autonomic nervous system and cell chemistry are greater than was previously thought. «For instance, noise – unwanted sound – stimulates the sympathetic system of the autonomic nervous system, causing raised arterial pressure, the metabolism and more rapid breathing. Disruption of these functions is exhibited in headaches, nausea, muscle contractions, nervous symptoms, fatigue, and psychosomatic disturbances. «The level of cholesterol in the blood rises, and it drops when noise is reduced. One indirect effect of noise is that it disrupts sleep, as noise makes sleep lighter, affecting its quality.» Noise has a deleterious effect on human hearing, and can cause temporary or permanent deafness. Damage occurs when noise rises above 80 decibels, and depending on the duration of exposure. «We should know that in practice 90 decibels is the permissible limit for an eight-hour working day,» said Maroudias. «A worker may be exposed to 100 decibels for two hours and 115 decibels for 15 minutes, but under no circumstances to more than 115 decibels.» Permanent deafness caused by noise cannot be restored and must be avoided by the use of preventive measures. These include inspection of the workplace, construction of barriers between noise sources and work areas, proper layout of work areas to limit echoes, and organization of the working day so that workers can have regular breaks. If there is no other way of protecting their hearing, workers must be provided with special earplugs. The dangers of noise in the workplace have been demonstrated in a study performed by the hearing unit at the ORL department of Aghia Olga Hospital and the Work Medicine department of IKA from April to June 1991 on 240 employees of Greek steelworks. The study revealed that 45 percent of those examined had suffered acoustic damage through exposure to noise.