Scattering Coefficient and Participate Matter Concentration in Forest Fire Smoke

Abstract

This paper is directed to those individuals concerned about measuring paniculate matter concentrations with portable light-scattering instruments. Extensive studies have been conducted of the relation between the light-scattering coefficient and particulate matter concentration in urban aerosols. There have been only a few studies to determine if this relation holds for single source aerosols such as those from forest fires. To gain further knowledge of this relation, light scatter in a nephelometer (b_scat ) and particulate matter concentration (M) were measured simultaneously at 11 low-intensity prescribed forest fires in Georgia and Florida. Analysis of the data with a least squares regression through the origin gives a M/b_scat ratio of 2.8 × 10⁵ μg/m² with 90% confidence limits of ± 0.1 × 10⁵ μg/m². Comparison of this ratio with that from other studies is hampered by their use of nephelometers with different spectral responses and/or different methods of analysis. A table is presented comparing all ratios after compensating for these differences.