Bradley James Ingebrethsen

Evolution of the Particle Size Distribution of Mainstream Cigarette Smoke During a Puff

A procedure for the measurement of the particle size distribution of minimally aged undiluted mainstream cigarette smoke is presented. The angular dependence of scattered light intensity was measured and a best fit log normal distribution was determined by comparison of ratios of the scattering intensities to theoretically calculated values. The problem of multiple scattering by the concentrated mainstream smoke was overcome by aerodynamically focusing the sampled smoke to a fine stream in a specially designed photometer. The photometer required no dilution of the smoke and performed the measurement on smoke aged 0.12 s, minimizing coagulation. Size distributions were determined at 100 points during a 2-s puff revealing significant changes in the average diameter of the aerosol during the puff. The changes in particle size are shown to correlate with the changing flow profiles in the cigarette during the smoking process.

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.

A Comparative Study of Environmental Tobacco Smoke Particulate Mass Measurements in an Environmental Chamber

Particulate mass concentration measurements have been made on environmental tobacco smoke (ETS) for the purpose of assessing the relative accuracy of several measurement procedures. ETS over a range of concentrations was generated in an environmental chamber by three methods. Mass concentration was measured by a gravimetric/spectrophotometric collection procedure, piezoelectric particle mass monitors, two nephelometry-based mass monitors, and a particle counting and sizing system. Two-hour average mass concentrations were determined by each method for concentrations ranging from very low levels up to those achieved by smoking one entire cigarette in the chamber. Statistical comparisons were made among procedures employing the gravimetric filter measurement as the basis for comparison. One nephelometry-based procedure gave significantly higher and the other significantly lower values than the filter determination. In one case, a correction for the difference between the particle mass density of the calibra...

Particle Formation and Growth in Gases from Totally Filtered Mainstream Cigarette Smoke

Aerosol particle formation and growth has been observed in aging, initially particle-free gases obtained from filtered mainstream cigarette smoke. The time scale of particle formation and growth was on the order of minutes and was highly dependent on cigarette tobacco type. Measurements by both ensemble and single particle light-scattering methods were consistent with scattering from an aerosol with a fixed number of particles that grow into the tenth micron range. The rate of particle size increase agreed best with that predicted for growth controlled by condensable species formation by gas-phase reaction slower than the diffusion rate of the reaction products. A simple reaction scheme involving nitrogen oxide oxidation and reaction with isoprene reproduced the observed form of the particle growth curves but did not yield a consistent reaction rate constant for the various cigarette tobacco types, suggesting that additional reactants are involved in the particle formation.