Fact file

Black carbon (“black carbon” in English, sometimes also called soot carbon) is the carbon part of fine particles resulting from incomplete combustion. It is referred to as “black” because it absorbs all radiation from visible light. Black carbon is part of the family of fine particles (diameter less than 2.5 microns) and its lifespan in the atmosphere ranges from a few days to a few weeks.


Origin of pollution

Black carbon is produced by the incomplete combustion of (1) fossil fuels associated with transport (mainly diesel), (2) wood or charcoal used for domestic heating, (3) agricultural waste and forest fires.

Black carbon is a stable compound and almost exclusively of anthropogenic origin. It is therefore a good indicator for studying the impact of policies for the reduction of polluting emissions linked to traffic or domestic heating.


Health effects

Like all fine particles, black carbon is likely to enter the respiratory system, settle there, and trigger inflammation of lung tissue. In addition, the finest particles can pass into the blood through the alveoli, increasing cardiovascular risks.

Alongside this "physical" toxicity, black carbon is a vector of substances whose toxicity is recognised, such as VOCs, PAHs, metals, etc.


Environmental impact

Black carbon, first of all, has an impact on our living environment through the soot deposits that cover our environment and, in particular, our historical heritage (monuments, buildings, etc.).

The toxic substances associated with it (organic compounds, metals) are found disseminated in the environment, polluting the air, soil, surface water and groundwater.

Black carbon also contributes to global warming. Indeed, this compound strongly absorbs light rays coming from the sun and heats the surrounding air, which distinguishes it from greenhouse gases which, in turn, absorb the thermal radiation coming from the ground. According to some sources, black carbon is the second greatest cause of global warming, after carbon dioxide.


The situation in Wallonia

Measuring black carbon in Wallonia is relatively recent and, still, too little has been documented to judge its evolution. However, knowing that the measurement of black smoke strongly correlates with that of black carbon, it may be said that combustion residues have greatly decreased in recent decades.


Measurement methods

Black carbon is measured continuously and in real time by monitors using the principle of infrared absorption (aethalometer).

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