The bad science in city's incineration plan for househould waste
It's shameful that research into building an incinerator in Hong Kong does not properly address the hazards it may bring
There has been considerable brouhaha over Hong Kong's waste strategy, particularly plans to expand three landfills and build an incinerator on an artificial island by Shek Kwu Chau - which passed two votes in the Legislative Council but were then delayed, with the Finance Committee now set to vote on the plans in autumn.
While there is agreement on the wisdom of reducing and even halting landfill use, controversy swirls over ideas for heavy reliance on incineration. Arguments span issues such as location, aesthetics and costs. But what does science say?
Using incineration to reduce waste in landfills was a strategy adopted in Hong Kong from the late 1960s, leading to four waste incineration plants being built. Yet to the Environmental Protection Department, science showed incineration was a threat to human health.
"Incinerators are a major source of pollution," reported a 1989 government white paper on pollution. "They account for approximately 18 per cent of all respirable [particles] emitted into the atmosphere of the territory and can be a source also of trace quantities of highly toxic substances." All incinerators were then phased out by 1997.
But recently, there has been a remarkable about-face in the department's attitude to waste incineration. Assistant director Elvis Au boldly claimed that in the planned incinerator, temperatures of at least 850 degrees Celsius can completely destroy organic pollutants.
Alas, this is not true. Incinerators' emissions may include 200 or more kinds of organic compounds, including known carcinogens. It appears Au was misled into considering only dioxins - the most notorious toxins formed during combustion - and should indeed be destroyed at temperatures above 850 degrees Celsius, though can reform as chimney gases cool.