The coast guard, who is constantly monitoring the quantum of oil spill from the sunken merchant ship MV Rak, said the quantity of spillage has reduced to half tonne per hour. In a release issued in Mumbai Tuesday, coast guard said that the three ships and an aircraft deployed by them are constantly monitoring the extent of spillage and the damage caused by it. The release said that the coast guard helicopter undertook aerial assessment of extent of oil pollution at sea and along coast and observed the oil slick area considerably reduced. The coast guard said the ships sprayed Oil Spill Dispersant in heavily affected areas to neutralize oil patches and further informed that the operation Paryavaran Suraksha has been able to contain the spread of oil within 5 nautical miles from the sunken vessel. Meanwhile, the coast guard has also informed that area upto 12 nautical miles from the coast is now devoid of any oil patches.