The dioxin concentration in stack emissions at the Chemical Waste Treatment Centre in Tsing Yi are below international standards, the Civil Engineering & Development Department says.

Announcing an independent expert assessor's report at the Kwai Tsing District Council meeting today, the department said analysis of samples taken on February 25 and 27 showed the concentration of dioxin was 0.00065ng/cubic metre on average, well below the 0.1 standard.

The dioxin concentration in kiln-bottom ash was 1.49ng/kg on average, far below the most commonly acceptable soil contamination criteria of 1,000ng/kg. Ambient dioxin concentration at five Kwai Tsing locations ranged from 0.022 to 0.035pg/m3, all below the alert indicator of 0.1pg/m3.

The last batch of about 25 tonnes of dioxin-containing residues will be delivered from To Kau Wan to the centre on March 22.