2.Experimental
2.1 The Study Area
Islamabad,the capital city of Pakistan,is situated 500 m above sea level (Latitude 33 49 N;Longitude 72 24 E) covering an area of about 900 km2 supporting a population of more than one million. It is 25 km north of its twin city, Rawalpindi,with a population of more than three millon(Pakistan Bureau of Statistics 2004) .The inhabited land in Islamabad is divided into residential,industrial,and commercial sectors. The main industrial units are housed in sectors I-9 and I-10 .The major industries in the industrial area include steel mills,marble factories, flour mills ,oil and ghee units , soap/chemical factories,ceramic,paint,pigment,and pharmaceutical manufacturing plants,in addition to several other small industrial units.