Ruß

Ruß, in scientific terms soot or black carbon, is a form of carbonaceous particulate matter produced by incomplete combustion of carbon-containing fuels. It occurs in engines, furnaces and wildfires, and as an atmospheric pollutant. Culturally, the term also describes the dark soiling that accumulates on surfaces exposed to smoke.

Ruß particles are mainly elemental carbon, with varying amounts of organic carbon, trace metals and adsorbed organic compounds. They are predominantly submicron, typically 0.01 to 2 micrometers in diameter, and often form fractal aggregates. They absorb light strongly, which gives them their characteristic dark color and makes them influential in radiative forcing; aging in the atmosphere can change their surface properties.

Common sources include diesel and gasoline engines, residential heating with wood and coal, industrial furnaces, and biomass burning. Soot forms under fuel-rich, oxygen-limited combustion conditions; as the flame cools, polycyclic aromatic hydrocarbons associate and condense into solid particles that grow by coagulation.

Health effects are linked to inhalation of fine particles, contributing to respiratory and cardiovascular diseases. Environmentally, soot or black carbon absorbs sunlight, contributing to warming and climate change, and can deposit on snow and ice, reducing albedo and accelerating melt.

Measurements relate to fine particulate matter (PM2.5) with soot being a major component; mitigation includes cleaner fuels, engine and exhaust controls such as diesel particulate filters, and reduced residential burning. The term Ruß also historically referred to carbon black, a pigment produced by incomplete combustion used in inks and paints.