Electronic cigarettes: age-specific generation-resolved pulmonary doses.

Particle size-number distributions of aerosol from e-cigarettes (0 and 14 mg mL-1 nicotine) were compared with conventional cigarettes. Results were used to provide age-specific (9-21 years) dosimetry estimates applying the MMPD model. After a 2-s puff, total number doses (D Tot ) were highest for 9 years of age (6.01 × 1010-1.31 × 1011 particles) and lowest for 18 years of age (4.69 × 1010-1.06 × 1011 particles). Such doses represented about 19-45 and 25-100% of the relevant daily doses of not smoking individuals, respectively, in tracheobronchial (TB) and alveolar (A) regions. D Tot for the e-cigarettes were about double that for conventional cigarette. Deposition densities and daily volume of e-cigarette liquid deposited per unit surface area were maximum at lobar bronchi, highest for 9 years and lowest for 21 years age.

Aerosol deposition doses in the human respiratory tree of electronic cigarette smokers.

Aerosols from eight e-cigarettes at different nicotine levels and flavoring were characterized as particle number size distributions in the range 5.6-560 nm by FMPS and CPC. Results were used to provided osimetry estimates applying the MMPD model.Particle number concentrations varied between 3.26 x 10(9) and 4.09 x 10(9) part cm(-3) for e-liquids without nicotine and between 5.08 x 10(9) and 5.29 x 10(9) part cm(-3) for e-liquids with nicotine. No flavor effects were detected on particle concentration data. Particle size distributions were unimodal with modes between 107-165 nm and 165-255 nm, for number and volume metrics, respectively. Averagely, 6.25 x 10(10) particles were deposited in respiratory tree after a single puff. Highest deposition densities and mean layer thickness of e-cigarette liquid on the lung epithelium were estimated at lobar bronchi. Our study shows that e-cigarette aerosol is source of high particle dose in respiratory system, from 23%to 35% of the daily dose of a no-smoking individual.

School children's personal exposure to ultrafine particles in the urban environment.

There has been considerable scientific interest in personal exposure to ultrafine particles (UFP). In this study, the inhaled particle surface area doses and dose relative intensities in the tracheobronchial and alveolar regions of lungs were calculated using measured 24-h UFP time series of school children personal exposures. Bayesian hierarchical modeling was used to determine mean doses and dose intensities for the various microenvironments. Analysis of measured personal exposures for 137 participating children from 25 schools in the Brisbane Metropolitan Area showed similar trends for all participating children. Bayesian regression modeling was performed to calculate the daily proportion of children's total doses in different microenvironments. The proportion of total daily alveolar doses for home, school, commuting, and other were 55.3%, 35.3%, 4.5%, and 5.0%, respectively, with the home microenvironment contributing a majority of children's total daily dose. Children's mean indoor dose was never higher than the outdoor's at any of the schools, indicating there were no persistent indoor particle sources in the classrooms during the measurements. Outdoor activities, eating/cooking at home, and commuting were the three activities with the highest dose intensities. Children's exposure during school hours was more strongly influenced by urban background particles than traffic near the school.