EU Science Hub

High chlorine coal affects pollution from domestic stoves

A household stove with the fire lighting inside
May 28 2015

A study looking into the dioxin concentrations in flue gases – which are emitted from coal burnt in residential stoves – show they increase 100 times if the chlorine content in the fuel rises from 0.07% to 0.38%. While extreme dioxin concentration are deemed to be linked with high chlorine content of the coal, the study associates for the first time soaring dioxins concentration to specific chlorine content in coal.

Various studies have shown that domestic stoves burning coal release a higher level of toxic dioxins than modern waste incinerators. A study carried out by the JRC and two Slovenian research organisations included a series of controlled laboratory experiments to examine the effect of different chlorine content in coal in combination with different chimney configurations. The results showed that dioxin concentrations emitted from domestic stoves were a thousand times higher than those by a modern waste incinerator, with over 100 nanogrammes of toxicity equivalent per cubic metre (ng TEQ/m3). It was estimated that 90% of the dioxins in the flue gases were formed inside the chimney as a consequence of the combination of high chlorine coal and insulated chimney.

Although the use of wood and coal in residential heating appliances in urban areas has been projected to decline in Europe, this trend has not yet been observed, and even the opposite is true in some areas. This can be explained as a result of high energy prices, which drive low-income households to opt for cheaper heating alternatives. Therefore, dioxin emissions from coal combustion in residential stoves still represent an environmental issue which needs to be addressed. To limit emissions of the toxic dioxins, high chlorine coal in residential stoves must be avoided.

Polychlorinated dibenzo p-dioxins and furans (PCDD/F), often referred to as dioxins, are a group of aromatic compounds released during combustion as a result of specific chemical processes. They are among the most toxic known compounds, and are persistent in the environment and in the food chain. Their impacts on human health are of great concern to scientists, policy makers and general public. In urban areas, the combustion of wood and coal for domestic heating represents one of the major sources of particulate matter pollution.