An Apparatus for Generating Aged Cigarette Smoke for Controlled Human Exposure Studies

Abstract

Research has shown that cigarette smoke changes chemically and physically after it is released into indoor air, that these changes can increase secondhand smoke (SHS) toxicity, and that acute exposures to even low levels of SHS increase the risk of cardiopulmonary disease. We designed a system to reproduce realistic SHS exposures in the laboratory for use in controlled human exposure studies. We generated cigarette smoke with a smoking machine, diluted it and conducted it through a 6 m 3 stainless steel flow reactor at rates equivalent to the upper ranges of normal residential air exchange rates, to create aged cigarette smoke as a model for secondhand cigarette smoke. We observed that approximately 50% of the particle mass deposited within the system and that particle deposition percentage was higher when absorbent materials were placed within the system. The particle size ranges and deposition percentages, coefficients and velocities observed for this smoke aerosol are in good agreement with published values for SHS observed in residences and vehicles. This apparatus also permits the study of the physical and chemical interactions between SHS and indoor surfaces. The apparatus delivers stable aerosol concentra- Health and Human Services 2006). However, the mechanisms by which SHS exposure causes diseases other than cancer are still unclear. SHS is a complex and dynamic mixture made up of particles and gases that includes smoke from the burning end of the cigarette (sidestream smoke) and exhaled mainstream smoke (U.S. Department of Health and Human Services 1986). Recent evidence, from our laboratory and others, has shown that SHS undergoes numerous chemical and physical changes after it is released into the air. Nicotine and other semivolatile organic compounds in smoke adsorb to surfaces where they can react with oxidant gases present in SHS and ambient air to form new chemical compounds (Singer et al. 2002(Singer et al. , 2003Destaillats et al. 2006;Schick and Glantz 2007;Petrick et al. 2011).Subchronic and chronic exposure studies using laboratory animals have demonstrated that, when quantified on the basis of 1246 AGED CIGARETTE SMOKE FOR HUMAN EXPOSURE STUDIES 1247 particulate material mass, aged cigarette smoke is more toxic to the respiratory epithelium than fresh smoke (Schick and Glantz 2006). Thus, studies that use freshly generated cigarette smoke may not capture the health effects caused by SHS in the real world. We created an aged-cigarette-smoke generation system to reproduce human exposures to secondhand cigarette smoke in the real world as accurately as possible in the laboratory. Controlled exposure studies are an important tool for assessing the acute health effects of exposure to pollutant exposures in humans and the biological mechanisms underlying these health effects. By using human subjects, it is possible to eliminate the doubt and dispute involved when animal exposure data are used to set exposure limits for humans. Previous human exposure studies have used two essential methods to ge...

Thirdhand cigarette smoke in an experimental chamber: evidence of surface deposition of nicotine, nitrosamines and polycyclic aromatic hydrocarbons and de novo formation of NNK

“…The smoke aging system is described in detail in Schick and Farraro et al 26. Briefly, smoke generated by an automatic smoking machine (Model TE-10z, Teague Enterprises, Woodland, California, USA) was diluted into conditioned, filtered air, and conducted through a 6 m 3 stainless steel aging chamber.…”

Thirty Minute-Exposure to Aged Cigarette Smoke Increases Nasal Congestion in Nonsmokers

“…These data suggest that there are significantly higher levels of the tobacco-specific nitrosamine NNK in SHS. Previous studies showed that the ratio of NNK:nicotine in the aged smoke aerosol generated in our lab is approximately 4 × 10 −4 (Schick et al, 2012a). The ratio of NNK:nicotine in fresh mainstream smoke is approximately 2 × 10 −6 and in fresh sidestream smoke it is approximately 1×10 −4 (IARC Working Group on the Evaluation of Carcinogenic Risks to Humans and World Health Organization, 2004).…”

“…Subjects were exposed to aged cigarette smoke generated in a custom-built system in the lab (Schick et al, 2012a). Cigarette smoke was generated with a smoking machine (TE10z, Teague Enterprises, Woodland, CA), diluted with conditioned, filtered air,and conducted through a large flow reactor at rates equivalent to the upper ranges of normal residential air exchange rates, creating aged cigarette smoke as a model for SHS.…”

Construction and Characterization of an Indoor Smog Chamber for the Measurement of the Optical and Physicochemical Properties of Aging Biomass Burning Aerosols Native to sub-Saharan Africa

“…In one study with cigarette smoke, particle deposition to chamber walls ranged from 23 % to 78 %, which is dependent on the wall material and independent of particle concentration and flow rate (Schick et al, 2012). Other studies 350 simulated the chamber wall loss of particles and vapors from BB smoke (Bian et al, 2015;Trump et al, 2016).…”

“…Smog chambers (both indoor and outdoor) have been used, beginning in the 1960s, to study atmospheric processes in controlled environments, such as biomass burning emissions (Kamens et al, 1984;Hennigan et al, 2011;Bian et al, 2015), SOA production (Carter et al, 2005;Babar et al, 2016), diesel exhaust (Weitkamp et al, 85 2007), and cigarette smoke (Schick et al, 2012). As opposed to in situ measurements, the aging process can be studied over longer times in a chamber with greater temporal accuracy and sampling frequency.…”