Smoke Emission Factors from Medium-Scale Fires: Part 2

Smoke emission factors, (i.e., the mass of smoke per mass of fuel burned), were measured in 11 separate experiments. The size distribution of the smoke particles was determined using a cascade impactor. The percentages of “black” carbon (also called “graphitic” or “elemental” carbon) and organic carbon have been determined for all the experiments as a function of particle aerodynamic diameter. Values in the range of 0.1%–0.2% are reported for the smoke particle emission factors for Douglas fir whole wood and plywood burning under well-ventilated conditions. Approximately 65% of the particles have aerodynamic diameters less than 1 μm. Douglas fir whole wood gave smoke emission factors in the range of 2%–3.5% when burned under poorly ventilated conditions representative of a building fire that is limited by air entrainment. For this case the size distribution was much broader, with substantial quantities of particles up to 5-μm aerodynamic diameter. For all ex periments, the black carbon content represented between 50% and 75% of the total mass of the smoke particles. The smoke emission factor for burning asphalt roofing shingles is reported as 12.1% with a black carbon content greater than 70%. Over half of the mass consisted of particles of less than 1-μm aerodynamic diameter.