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These plots show PM2.5 mass concentration and equivalent black carbon concentration measured during the past week, estimated from optical measurements of aerosol light scattering and absorption. Black carbon is a product of incomplete combustion of carbonaceous fuels from diesel engines, fires, etc. The PM2.5 mass concentration is estimated using a mass scattering efficiency of 3 m²/g, and the equivalent black carbon concentration is estimated using a mass absorption efficiency of 6 m²/g. The time axis is Coordinated Universal Time (UTC).

These measurements are made as part of a climate research network coordinated by the NOAA Earth System Research Laboratory. The NOAA/ESRL/GMD aerosol group also makes these measurements in their lab in Boulder CO.