Carbon-containing compounds are frequently the largest component of particulate matter in the atmosphere and comprise a vast range of species.

At one end of this range is a “haze of natural origins,” often seen over forests in the summertime.  This ‘secondary’ aerosol is formed by atmospheric reactions of organic vapor precursors and is almost colorless.  It scatters light, creating a haze: but it does not absorb light.

An example is smoke from biomass burning (e.g., wood smoke, burning of agricultural materials) in the middle of this range.  This smoke contains both light-scattering organic materials and light-absorbing “Brown” and “Black” carbon material.  Wood smoke contains many aromatic compounds, some of which may be toxic or mutagenic/carcinogenic.

At the other end of the range is the example of diesel exhaust.  This material has a very pronounced ‘Black Carbon’ component, in addition to associated aromatics, which may be adsorbed onto the surface of the black particles.  The adsorbed aromatics lead to the serious health impacts of diesel emissions: but the absorption of light- the ‘Black’ coloration – has many other adverse geophysical effects.

Suspended in the air, Black Carbon particles absorb sunlight and heat the atmosphere.  Incorporated into cloud droplets, they reduce the cloud albedo (reflectivity).  When deposited onto snow or ice, sunshine is absorbed rather than reflected.  This leads to accelerated thawing and contributes to the disappearance of glaciers and the loss of the Arctic ice cover.

Carbonaceous aerosols are the major, dominant component of the mass of suspended particles in polluted atmospheres.  Their composition spans the range from ‘Organic Carbon’ (often denoted “OC”); to ‘Black’ or ‘Elemental’ Carbon (denoted “BC” or “EC”).  Instruments manufactured by Aerosol under the Magee Scientific brand name, measure in real time both the ‘Black’; ‘Brown’; and ‘Total’ carbon content of suspended particles. These instruments are rugged, reliable, and are suitable for use in every application from research laboratories to field projects to routine air-quality monitoring stations.

Other than forest fires, human activities are the main source of carbonaceous aerosols.  These emissions can be greatly reduced by improved combustion efficiency and exhaust treatment.  However, accurate and reliable data are always needed: to assess the severity of the problem, identify the main sources that require attention, and quantitate the improvements following the application of controls and regulations. “To manage a problem, you must be able to measure it.”  Magee Scientific instruments made by Aerosol provide this accurate data – automatically, reliably, anywhere.