KUALA LUMPUR, Nov 11 — The level of odour pollution at the Muka Sauk Water Treatment Plant (LRA), Rantau Panjang has dropped to 4 TON (threshold odour number) as at 11pm yesterday while that for Sungai Selangor LRA Phases (SSP) 1, 2 and 3 has decreased to 1 TON.