Clearing the smoke - understanding the impacts of black carbon pollution : air pollution

Black carbon (BC), more commonly known as 'soot', is perhaps one of the most important airborne pollutants. It is present as particles in the atmosphere at a size <0.3 µ that can be ingested deep into lungs and has a very large active, adsorptive surface area, which can carry many potentially harmful substances into the respiratory system. Furthermore, BC is second only to CO2 in the global warming stakes, as it reduces aerosol albedo, causing a reduction of cloud cover and of cloud particle albedo in turn. BC can also deposit on the snow and ice of the Artic and Antarctic, causing them to darken and absorb heat which accelerates melting and rising of sea levels around the globe. BC is not lost from the atmosphere by chemical processes like many other pollutants - it is lost only by deposition. Up to 90% of the BC found in urban air is from diesel exhaust, making BC an excellent indicator of urban pollution from traffic. As BC is formed by combustion processes involving all carbon fuels, it is a major problem for air quality agencies around the world; yet, to date, is not as highly regulated as many other, arguably less harmful pollutants. This paper explores sources of BC, local, regional and global effects on public health and climate change and the options for monitoring, understanding and controlling BC concentrations.