A comparison of infrared extinction performances of bioaerosols and traditional smoke materials

Abstract

Infrared smoke refers to an aerosol system with specific laws of motion formed by numerous solid and liquid particles suspended in atmosphere. Previous research concentrates on the extinction performance of traditional IR smoke materials while new research focusses on bioaerosols. The complex refractive indices of traditional smoke materials and bioaerosols in the 2.5–15 μm wavebands were calculated. Moreover, IR transmittances of different smoke materials in the smoke box experiment were measured to calculate their mass extinction coefficients. The results showed that, in the wavebands of 2.5–15 μm, the IR scattering ability of traditional smoke materials was generally stronger than that of bioaerosols. The IR absorbency of bioaerosols was weaker than those of aluminium, graphite, and silica powders while was stronger than those of copper, iron, and red phosphorus powders. The overall IR extinction performances of the three kinds of bioaerosols (AN, AO, and BB spores) in the wavebands of 3–5 μm and 8–14 μm were inferior to those of aluminium and graphite powders while superior to those of silica, copper, iron, and red phosphorus powders. The average transmittances of the aforementioned three kinds of bioaerosols in the wavebands of 3–5 μm were all less than 10% and their mass extinction coefficients were 0.66, 0.73, and 0.75 m2/g, respectively. Moreover, their average transmittances in the wavebands of 8–14 μm were 24.1%, 15.56%, and 15.04% and mass extinction coefficients were 0.36, 0.47, and 0.48 m2/g, respectively. The results provide a reference for those investigating new IR smoke materials.