scholarly journals Effect of electronic cigarette (EC) aerosols on particle size distribution in indoor air and in a radon chamber

Nukleonika ◽  
2019 ◽  
Vol 64 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Hyam Nazmy Khalaf ◽  
Mostafa Y. A. Mostafa ◽  
Michael Zhukovsky
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Indoor Air ◽  
Size Range ◽  
Aerosol Particles ◽  
Ultrafine Particle ◽  
Decay Product ◽  
Electronic Cigarette ◽  
Particle Size Range

Abstract Particle size distribution is an important factor governing whether aerosols can be deposited in various respiratory tract regions in humans. Recently, electronic cigarette (EC), as the alternative of tobacco cigarette, has become increasingly popular all over the world. However, emissions from ECs may contribute to both indoor and outdoor air pollution; moreover, comments about their safety remain controversial, and the number of users is increasing rapidly. In this investigation, aerosols were generated from ECs and studied in the indoor air and in a chamber under controlled conditions of radon concentration. The generated aerosols were characterized in terms of particle number concentrations, size, and activity distributions by using aerosol diffusion spectrometer (ADS), diffusion battery, and cascade impactor. The range of ADS assessment was from 10−3 μm to 10 μm. The number concentration of the injected aerosol particles was between 40 000 and 100 000 particles/cm3. The distribution of these particles was the most within the ultrafine particle size range (0–0.2 μm), and the other particle were in the size range from 0.3 μm to 1 μm. The surface area distribution and the mass size distribution are presented and compared with bimodal distribution. In the radon chamber, all distributions were clearly bimodal, as the free radon decay product was approximately 1 nm in diameter, with a fraction of ~0.7 for a clean chamber (without any additional source of aerosols). The attached fraction with the aerosol particles from the ECs had a size not exceeding 1.0 μm.

scholarly journals Size distributions of polycyclic aromatic hydrocarbons in urban atmosphere: sorption mechanism and source contributions to respiratory deposition

2016 ◽  
Vol 16 (5) ◽  
pp. 2971-2983 ◽  
Author(s):  
Yan Lv ◽  
Xiang Li ◽  
Ting Ting Xu ◽  
Tian Tao Cheng ◽  
Xin Yang ◽  
...  
Keyword(s):  
Particle Size ◽  
Polycyclic Aromatic Hydrocarbons ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Respiratory System ◽  
Aromatic Hydrocarbons ◽  
Size Range ◽  
Particle Size Range ◽  
Polycyclic Aromatic ◽  
Human Respiratory System

Abstract. In order to better understand the particle size distribution of polycyclic aromatic hydrocarbons (PAHs) and their source contribution to human respiratory system, size-resolved PAHs have been studied in ambient aerosols at a megacity Shanghai site during a 1-year period (2012–2013). The results showed the PAHs had a bimodal distribution with one mode peak in the fine-particle size range (0.4–2.1 µm) and another mode peak in the coarse-particle size range (3.3–9.0 µm). Along with the increase in ring number of PAHs, the intensity of the fine-mode peak increased, while the coarse-mode peak decreased. Plotting of log(PAH / PM) against log(Dp) showed that all slope values were above −1, suggesting that multiple mechanisms (adsorption and absorption) controlled the particle size distribution of PAHs. The total deposition flux of PAHs in the respiratory tract was calculated as being 8.8 ± 2.0 ng h−1. The highest lifetime cancer risk (LCR) was estimated at 1.5  ×  10−6, which exceeded the unit risk of 10−6. The LCR values presented here were mainly influenced by accumulation mode PAHs which came from biomass burning (24 %), coal combustion (25 %), and vehicular emission (27 %). The present study provides us with a mechanistic understanding of the particle size distribution of PAHs and their transport in the human respiratory system, which can help develop better source control strategies.

scholarly journals Blend of natural waxes as a matrix for aroma encapsulation

2017 ◽  
Vol 15 (2) ◽  
pp. 103-111
Author(s):  
Jelena Milanovic ◽  
Gordana Ilic-Sevic ◽  
Marijana Gavrilovic ◽  
Milutin Milosavljevic ◽  
Branko Bugarski
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Elevated Temperatures ◽  
Thermal Characteristics ◽  
Feed Additives ◽  
Morphological Properties ◽  
Particle Size Range ◽  
Carnauba Wax ◽  
Potential Applications

In this study, the possibility of using a blend of natural waxes (bees and carnauba) for encapsulation of some aroma compounds was investigated. Melt dispersion/melt solidification technique was applied for microbeads production. Since one of the most important characteristics of the particles are the size and shape, particle size distribution as well as morphological properties are tested. Thermal characteristics are also examined as significant properties for thermal behavior at elevated temperatures, important for application of encapsulated particles in food production processes. Different contents of the carnauba wax in the mixture with beeswax are investigated, from 10% to 50% (w/w). Since one of the potential applications of the encapsulated aroma is in feed additives production, the targeted particle size range was under 300 ?m to be suitable for handling and mixing with other powder substances. According to the obtained results, a higher carnauba wax content in the wax blend had an impact on particle size distribution. Also, it had an impact on the surface morphology and thermal properties. The obtained results may contribute to the development of methods of encapsulation of hydrophobic aromas in the natural wax matrix.

scholarly journals Particle size distribution and particle mass measurements at urban, near-city and rural level in the Copenhagen area and Southern Sweden

2003 ◽  
Vol 3 (6) ◽  
pp. 5513-5546 ◽  
Author(s):  
M. Ketzel ◽  
P. Wåhlin ◽  
A. Kristensson ◽  
E. Swietlicki ◽  
R. Berkowicz ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Particle Number ◽  
Size Range ◽  
Urban Background ◽  
Total Particle ◽  
Urban Level ◽  
20 Nm ◽  
Traffic Source

Abstract. Particle size distribution (size-range 3–900 nm) and PM10 was measured simultaneously at an urban background station in Copenhagen, a near-city background and a rural location during a period in September-November 2002. The study investigates the contribution from urban versus regional sources of particle number and mass concentration. The total particle number (ToN) and NOx are well correlated at the urban and near-city level and show a distinct diurnal variation, indicating the common traffic source. The average ToN at the three stations differs by a factor of 3. The observed concentrations are 2500 # cm−3, 4500 # cm−3 and 7700 # cm−3 at rural, near-city and urban level, respectively. PM10 and total particle volume (ToV) are well correlated between the three different stations and show similar concentration levels, in average within 30% relative difference, indicating a common source from long-range transport that dominates the concentrations at all locations. Measures to reduce the local urban emissions of NOx and ToN are likely to affect both the street level and urban background concentrations, while for PM10 and ToV only measurable effects at the street level are probable. Taking into account the supposed stronger health effects of ultrafine particles reduction measures should address particle number emissions. The traffic source contributes strongest in the 10–200 nm particle size range. The maximum of the size distribution shifts from about 20–30 nm at kerbside to 50–60 nm at rural level. We also observe particle formation events in the 3–20 nm size range at rural location in the afternoon hours, mainly under conditions with low concentrations of pre-existing aerosol particles. The maximum in the size distribution of the "traffic contribution" seems to be shifted to about 28 nm in the urban location compared to 22 nm at kerbside. Assuming NOx as an inert tracer on urban scale let us estimate that ToN at urban level is reduced by 15–30% compared to kerbside. Particle removal processes, e.g. deposition and coagulation, which are most efficient for smallest particle sizes (<20 nm) and condensational growth are likely mechanisms for the loss of particle number and the shift in particle size.

scholarly journals Electronic cigarette power affects count concentration and particle size distribution of vaping aerosol

PLoS ONE ◽  
2018 ◽  
Vol 13 (12) ◽  
pp. e0210147 ◽  
Author(s):  
Evan L. Floyd ◽  
Lurdes Queimado ◽  
Jun Wang ◽  
James L. Regens ◽  
David L. Johnson
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Electronic Cigarette

Electronic cigarette aerosol particle size distribution measurements

2012 ◽  
Vol 24 (14) ◽  
pp. 976-984 ◽  
Author(s):  
Bradley J. Ingebrethsen ◽  
Stephen K. Cole ◽  
Steven L. Alderman
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Aerosol Particle ◽  
Electronic Cigarette ◽  
Aerosol Particle Size

scholarly journals Factors determining the most efficient spray distribution for marine cloud brightening

2014 ◽  
Vol 372 (2031) ◽  
pp. 20140056 ◽  
Author(s):  
P. J. Connolly ◽  
G. B. McFiggans ◽  
R. Wood ◽  
A. Tsiamis
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Energy Efficient ◽  
Aerosol Particles ◽  
Care Needs ◽  
Salt Particle ◽  
Aerosol Particle Size ◽  
Spray Distribution ◽  
Added Salt

We investigate the sensitivity of marine cloud brightening to the properties of the added salt particle distribution using a cloud parcel model, with an aim to address the question of, ‘what is the most efficient particle size distribution that will produce a desired cooling effect?’ We examine the effect that altering the aerosol particle size distribution has on the activation and growth of drops, i.e. the Twomey effect alone, and do not consider macrophysical cloud responses that may enhance or mitigate the Twomey effect. For all four spray generation methods considered, Rayleigh jet ; Taylor cone jet ; supercritical fluid ; and effervescent spray , salt particles within the median dry diameter range D m =30–100 nm are the most effective range of sizes. The Rayleigh jet method is also the most energy efficient overall. We also find that care needs to be taken when using droplet activation parametrizations: for the concentrations considered, Aitken particles do not result in a decrease in the total albedo, as was found in a recent study, and such findings are likely to be a result of the parametrizations' inability to simulate the effect of swollen aerosol particles. Our findings suggest that interstitial aerosol particles play a role in controlling the albedo rather than just the activated cloud drops, which is an effect that the parametrization methods do not consider.

Reconstructed expression for aerosol extinction coefficient by considering mass extinction efficiency and hygroscopic growth for polydipersed aerosol

2020 ◽  
Author(s):  
Chang Hoon Jung ◽  
JiYi Lee ◽  
Junshik Um ◽  
Yong Pyo Kim
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Growth Factor ◽  
Size Distribution ◽  
Enhancement Factor ◽  
Size Range ◽  
Geometric Mean ◽  
Mie Theory ◽  
Hygroscopic Growth ◽  
Particle Size Range

&lt;p&gt;In this study, simplified analytic type of expression for size dependent MEs (Mass efficiencies) are developed. The entire size was considered assuming lognormal size distribution for sulfate, nitrate and NaCl aerosol species and the MEE of each aerosol chemical composition was estimated by fitting Mie&amp;#8217;s calculation. The obtained results are compared with the results from the Mie-theory-based calculations and showed comparable results.&lt;/p&gt;&lt;p&gt;The mass efficiencies of all aerosol components for each size range are compared with Mie&amp;#8217;s results and approximated as a function of geometric mean diameter in the form of a power law formula. Finally, harmonic mean type approximation was used to cover entire particle size range.&lt;/p&gt;&lt;p&gt;Also, analytic expression of approximated scattering enhancement factor which stands for the effect of hygroscopic growth factor for polydispersed aerosol on aerosol optical properties are obtained.&lt;/p&gt;&lt;p&gt;Based on aerosol thermodynamic models, mass growth factor can be obtained and their optical properties can be obtained by using Mie theory with different aerosol properties and size distribution. Finally, scattering enhancement factor was approximated fRH for polydispersed aerosol as a function of RH.&lt;/p&gt;&lt;p&gt;Finally, we also compared the simple forcing efficiency (SFE, W/g) of polydisperse aerosols between the developed simple approach and by the method using the Mie theory. The results show that current obtained approximated methods are comparable with existing numercal calculation based results for polydipersed particle size.&lt;/p&gt;

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