1,721,113 research outputs found
Lung cancer risk assessment at receptor site of a waste-to-energy plant
No full textThe toxicity of particulate matter emitted from waste-to-energy plants, is associated to the compounds attached to the particles, several of which have been classified by the International Agency for Research on Cancer (IARC) in the Group 1 carcinogens. In this paper a modified risk-assessment model, deriving from an existing one, was applied to estimate the lung cancer risk related to both ultrafine and coarse particles emitted from an incinerator whose people living nearby are exposed to. To this end, the measured values of Polycyclic Aromatic Hydrocarbons (PAHs), heavy metals (As, Cd, Ni) and PCDD/Fs (Polychlorinated dibenzodioxins/furans) emitted from an incinerator placed in Italy were used to calculate the Excess Lifetime Cancer Risk (ELCR) at the stack of the plant. The estimated ELCR was then used as input data in a numerical CFD (Computational Fluid Dynamics) model that solves the mass, momentum, turbulence and species transport equations to study the influence of wind speed and chimney height on the ELCR at receptor sites. Furthermore, combining meteorological data (wind speed and direction), and hypothesizing different exposure scenarios on the basis of time-activity patterns of people living nearby the plant, specific risk maps were obtained by evaluating ELCR around the incinerator. Results show that with the increasing of wind speed, the ELCR value downwind at the plant decreases and its point of maximum risk becomes closer to the stack. On the other hand, increasing the stack height decreases the ELCR, moving away from the stack the point of maximum risk. Finally, the risk maps for people living or working nearby the plant have highlighted that the excess risk of lung cancer due to the presence of the incinerator is below the WHO target (1 × 10−5)
Measurements of electronic cigarette-generated particles for the evaluation of lung cancer risk of active and passive users
No full textHighlights\ud
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• Particle number and surface area concentrations were measured in e-cigs aerosol\ud
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• Literature analysis was carried out to evaluate Group 1 carcinogens onto particles\ud
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• Excess lifetime cancer risk was assessed for mainstream and second-hand aerosol\ud
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• Higher particle number concentration were measured with respect to traditional cigs\ud
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• Lower ELCR values were found for e-cigs with respect to traditional cig
Smokers’ lung cancer risk related to the cigarette-generated mainstream particles
No full textHighlights\ud
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• Application of a lung cancer risk model to smokers considering ultrafine particles\ud
• Measurement of particle concentrations in cigarette-generated mainstream aerosol\ud
• Excess life cancer risk for Italian smokers equal 2–6×10<sup>−1</sup>\ud
• Main contribution to the ELCR due to tobacco-specific nitrosamines\ud
• Great contribution due to the ultrafine particles (i.e. surface area metrics)\ud
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Abstract\ud
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Cigarette smoking represents the main cause of lung cancer events. This is due to the carcinogenic compounds condensed onto particles generated during the combustion process and then inhaled through the mainstream side (i.e. the cigarette filter side) of the cigarette. The present paper applied a novel lung cancer risk model, able to take into account both ultrafine and coarse particle toxicity, to the particle concentration levels measured in the mainstream aerosol of cigarettes in order to provide a useful provisional tool for testing different smoking scenarios.\ud
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To this end particle distributions and total concentrations in terms of number, surface area and mass aerosol metrics were measured at the mainstream side of five different cigarette brands using a condensation particle counter as well as mobility/aerodynamic particle sizers. On the basis of Italian smoking patterns and cigarette consumptions, the excess life cancer risk (ELCR) was then evaluated.\ud
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Particle concentrations equal to 3–6×10<sup>8</sup> part. cm<sup>−3</sup>, 60–120 mm<sup>2</sup> cm<sup>−3</sup>, and 5–9 g m<sup>−3</sup> for number, surface area and mass metrics, respectively, were measured. Most probable ELCR values ranged from 2×10<sup>−1</sup> to 6×10<sup>−1</sup> with the higher contribution due to the tobacco-specific nitrosamines and a minor (but still not negligible) contribution of B[a]p, Cd, and As.\ud
Keywords\ud
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excess lifetime cancer risk (ELCR); ultrafine particles; dose; cigarette; tobacco; SMPS; APS; lung cance
Characterization of particle emission from laser printers
No full text<b>Highlights</b>\ud
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- 110 laser printers from 7 manufacturers were analyzed in an experimental chamber.\ud
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- Particle number and mass concentrations, and size distributions, were measured.\ud
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- Emission rates for all the printers were calculated under fixed operational conditions.\ud
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- Daily surface area dose received by employees was estimated from emission rates.\ud
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- Relatively low total surface area dose (2.7 mm<sup>2</sup>) was estimated for office employees.\ud
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<b>Abstract</b>\ud
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Emission of particles from laser printers in office environments is claimed to have impact on human health due to likelihood of exposure to high particle concentrations in such indoor environments. In the present paper, particle emission characteristics of 110 laser printers from different manufacturers were analyzed, and estimations of their emission rates were made on the basis of measurements of total concentrations of particles emitted by the printers placed in a chamber, as well as particle size distributions. The emission rates in terms of number, surface area and mass were found to be within the ranges from 3.39×10<sup>8</sup> part. min<sup>-1</sup> to 1.61×10<sup>12</sup> part. min<sup>-1</sup>, 1.06×10<sup>0</sup> mm<sup>2</sup> min<sup>-1</sup> to 1.46×10<sup>3</sup> mm<sup>2</sup> min<sup>-1</sup> and 1.32×10<sup>-1</sup> µg min<sup>-1</sup> to 1.23×10<sup>2</sup> µg min<sup>-1</sup>, respectively, while the median mode value of the emitted particles was found equal to 34 nm.\ud
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In addition, the effect of laser printing emissions in terms of employees’ exposure in offices was evaluated on the basis of the emission rates, by calculating the daily surface area doses (as sum of alveolar and tracheobronchial deposition fraction) received assuming a typical printing scenario. In such typical printing conditions, a relatively low total surface area dose (2.7 mm<sup>2</sup>) was estimated for office employees with respect to other indoor microenvironments including both workplaces and homes. Nonetheless, for severe exposure conditions, characterized by operating parameters falling beyond the typical values (i.e. smaller office, lower ventilation, printer located on the desk, closer to the person, higher printing frequency etc.), significantly higher doses are expected
Aerosol deposition doses in the human respiratory tree of electronic cigarette smokers
No full textAerosols 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 provide dosimetry estimates applying the MMPD model. Particle number concentrations varied between 3.26 Ã 109 and 4.09 Ã 109 part cm-3 for e-liquids without nicotine and between 5.08 Ã 109 and 5.29 Ã 109 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 Ã 1010 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
Physiological responses to acute airborne particle exposure during maximal aerobic power
No full textWe measured physiological effects of airborne particle exposure in athletes.\ud
Intensity exercise close to maximal aerobic capacity was considered.\ud
Particles were generated through incense-burning indoor phenomena.\ud
Statistically significant differences were found between high and low scenarios.\ud
No differences were measured in terms of exhaled nitric oxide
A simplified benchmark of ultrafine particle dispersion in idealized urban street canyons: A wind tunnel study
No full textThe paper proposes a benchmark for computational fluid-dynamic models of ultrafine particle (particles' diameter lower than 100nm) dispersion in urban street canyons. In particular, an on-scale symmetric street canyon was designed and settled in a wind tunnel considering a perpendicular wind condition. An experimental campaign was carried out to: i) investigate the fluid-dynamic conditions inside the canyon through a Particle Image Velocimetry (PIV), ii) evaluate the uncertainty budget of the PIV measurements, iii) design proper particle injection and sampling systems in the street canyon not influencing the fluid-dynamic conditions of the canyon itself, iv) provide particle number concentration profiles at different sections of the canyon (at different heights on both the canyon facades and at a background level) through ultrafine particle generation (Submicrometer Aerosol Generator 3940, TSI Inc.) and measuring devices (CPC 3775 and SMPS 3936, TSI Inc.).The study can be considered the very first attempt to set a benchmark for ultrafine particle dispersion in street canyons through wind tunnel systems
Air permeability of naturally ventilated Italian classrooms
Full text linkThe study is focused on the evaluation of air permeability and ventilation rate in Italian classrooms. Measurements were performed in 16 naturally ventilated classrooms located in Cassino, Central Italy. Classrooms' airtightness was evaluated through the fan pressurization method. Air exchange rates where both estimated from the blower door results and measured using a CO2 decay test method. The effect of the periodic manual airing of the classrooms (through window and door opening) was also investigated performing CO2 and particle number concentration measurements during the school time
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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