Stephen Benson Sears

Particle evaporation of sidestream tobacco smoke in a stirred tank

Abstract The impact of environmental tobacco smoke (ETS) on indoor air quality has become a topic of widening public interest. While the fate of ETS particulate matter in field environments is governed by the laws of aerosol dynamics, analysis is complicated by numerous unknown and uncontrollable factors. The present study follows the aging process of sidestream tobacco smoke diluted into a 0.45 m3 stainless-steel stirred tank under controlled conditions of smoke concentration, air exchange, and mixing rate. Time-dependent measurements were made on the aerosol with an optical particle counter, an electrical mobility analyzer system, and a condensation nucleus counter. Long-time (>100 min after smoke generation) particle count decay rates were first order and explainable by air exchange and size-dependent surface removal. The shorter term decay included an “apparent” additional removal mechanism that was determined to be the result of particle evaporation with accompanying shrinkage and shifting of particle counts between size channels of the optical particle counter. Measurements of the particle size distribution of diluted sidestream smoke over an extended size range (all particles > 0.02 μm) are also reported.