A cloud of dust from the Sahara Desert made the atmosphere in Athens murky yesterday. The dust, which is normal for this time of year, was blown in by southerly winds. A change in the wind direction from late tonight is expected to help blow away the dust and clean up the atmosphere. The dust, which lingered over much of the country last week, has caused a number of people with respiratory problems, such as asthma, to seek medical treatment. Doctors advised old people to stay at home and those suffering from breathing problems to avoid working outdoors and to breathe through their noses rather than their mouths.