Multiple-Path Particle Dosimetry Research Articles

Determination of the delivered dose of nanoparticles in the trachea-bronchial and alveolar regions of the lung

Particle dosimetry is a necessary step for the risk assessment especially with regard to toxicological effects of nanoparticles. In many cases, dosimetry is linked to exposure via the surface area of the nanoparticles. Due to interface dependent reactions of particles and the lung tissue poorly soluble particles (PSP) are particularly in the focus of interest. In recent years the measurement the geometric particle surface area concentration, GSA, in the air and determination of the lung deposited surface area (LDSA) based on lung deposition models gained interest. The effective particle concentration in the Lung (LDSA) cannot be measured directly. The maxima of many common airborne particle surface area distributions occur in the particle size range below 400 nm. High alveolar and trachea-bronchial deposition can be encountered in this size range.In general, it is very difficult to measure the particle surface area directly. To measure particle surface area concentration in aerosols, online instruments were developed (e.g. nanoparticle surface area monitor - NSAM). These instruments are based on unipolar particle charging. To determine the charge level of single particles as a function of the particle size, the current of monodisperse particles is divided by the aerosol number concentration. In order to relate the total measured current of the entire size-distributions, the instrument response function has to have the same slope as the size-dependent particle surface area. Calibration allows putting these curves on top of each other at one specific particle size (no error). Any deviations of the two curves at other sizes cause errors.The first instrument based on this principle was NSAM. Its response function for the measurement of spherical particles shows a diameter dependency of d1.16. It was found that if the geometric surface area (GSA) of a particle is multiplied with the alveolar deposited fraction (alveolar deposition curve of the ICRP-model) the resulting curve has almost the same slope as the NSAM response function. In principle, this concept also works for the comparison with the deposition in the trachea-bronchial region. To date, only the LDSA (alveolar or trachea-bronchial) of spherical particles in human lungs based on the ICRP-model can be determined by the available instruments.To extend the application range of NSAM to other lung deposition models, e.g. the Multiple-Path Particle Dosimetry model (MPPD) which also provides the possibility to investigate particle deposition in animal lungs, we defined model-specific calibration factors. This allowed the correct determination of the surface area concentration at the calibration point (100 nm) and also facilitated the measurement at other particle diameters.We assessed whether the slope differences between the modified instrument responses and the calculated LDSA in the MPPD deposition models led to tolerable errors. First, we described the calculation of these errors as a function of the particle size. Using these size-dependent error functions the total error (for the measurement of an entire particle size distribution) can be determined if e.g. a known particle number size distribution is transferred into a surface area distribution. To present a possibility to estimate the errors without performing the described error calculations, we performed a systematic study. We determined the total error concerning the measurement of LDSA for two ambient real aerosols (combustion of diesel and firewood). For these very different particle size distributions and models for different animals, the errors were below 20%, which seemed tolerable. Therefore NSAM and other instruments with a similar working principle can be used to determine the LDSA with regard to particle deposition in human and animal lungs.

Evidences of copper nanoparticle exposure in indoor environments: Long-term assessment, high-resolution field emission scanning electron microscopy evaluation, in silico respiratory dosimetry study and possible health implications

A variety of appliances operated by brush electric motors, widely used in indoor environments, emit nanoparticles (NPs). Due to electric arc discharge during the operation of such motors, some NPs contain copper (Cu). Their dimensions are the same of those found in brain tissue samples by other authors who speculated their possible translocation to brain through olfactory bulb. Cu has been reported to play an important role in the etiopathogenesis of Alzheimer's disease. Thus, the present study was performed to 1. estimate by means of Multiple-Path Particle Dosimetry model the doses of NPs released by electric appliances that can potentially deposit on the olfactory bulb; 2. investigate the morphology and the composition of particles emitted by some electric appliances daily used in indoor environments; 3. monitor for a long time period the Cu contamination of indoor environments due to this kind of appliances. About 106–107 NPs deposit on the olfactory bulb during the operation (1.5–6 min) of such appliances, with a major contribution due to 10–20 nm NPs. HR-FESEM characterization confirmed the presence of such NPs, that were observed both as individual particles (20–40 nm) and aggregated to form particles in the μm sizes range. XEDS microanalysis revealed the presence of Cu together with other elements. Relevant daily contamination of indoor environments due to these appliances has been confirmed by monitoring throughout a year the Cu content of PM10 samples collected both indoor and outdoor private dwellings. Cu was present in great part as an insoluble form. This means that, following protracted exposure, Cu NPs of such origin may undergo tissue accumulation. This is cause of concern because general population is chronically exposed to such Cu nanoparticles in indoor environments and in view of the role assigned to Cu in the development of neurological disorders.

Application of multiple-path particle dosimetry model for quantifying age specified deposition of particulate matter in human airway

Particulate matter (PM) is crucial among six criteria air pollutants, and it is frequently associated with human morbidity and mortality. According to the aerodynamic diameter, PM is classified as coarse (PM10) and fine (PM2.5). PM with these smaller sizes can easily enter and get deposited in the human airways. This deposited PM fraction commences the development of respiratory diseases such as asthma, chronic obstructive pulmonary disease, and even cancer. Thus, the quantification of PM deposition and its clearance in the human airway are essential for evaluating health risks. This study aims to investigate the size-segregated PM (PM10, PM2.5, and PM1) deposition in human lungs. Size-segregated PM is collected using the Grimm portable environmental dust monitor during winter season near an arterial road located in Chennai city of Tamil Nadu state, India. Multiple-Path Particle Dosimetry (MPPD) Model version 3.04 is utilized for quantifying PM deposition. In MPPD, airway structures of infants (3 and 28 months), children (3, 8, 9 and 14 years) and adults (18 and 21 years) are considered for the study. The values of PM concentration, body orientation, breathing scenario, tidal volume, pause fraction, inspiration fraction, and breathing frequency are specified in the MPPD for quantifying PM depositions. Results showed that 8-year children and 28 months infant groups are recorded with maximum and minimum size-segregated PM deposition respectively. The coarse particles (PM10) are primarily deposited in the head (55–95%) and tracheobronchial (3–44%) regions whereas fine particles (PM2.5 and PM1) depositions are observed maximum in the head (36–63%) and pulmonary (28.2–52.7%) regions. Except for the adult age group, PM2.5 has the maximum deposition percentage in tracheobronchial and pulmonary regions. In the case of lobar depositions, lower lobes receive maximum deposition (66.4%) than the upper (27.2%) and middle lobes (6.4%). PM2.5 dominated the deposition in all five lobes of infant, children, and adults. The clearance rate of deposited PM is high in the tracheobronchial region whereas it is low in the pulmonary region. This study also concludes that PM2.5 is the important size fraction in lung deposition. Further, the study results can be used for human health risk assessments such as oxidative potential and toxicity of deposited PM.

Submicron particle number doses in the human respiratory tract: implications for urban traffic and background environments.

The deposition of ambient submicron particles in the different parts of the human respiratory tract (HRT) was, for the first time, estimated for males and females from different age classes (children-adults-seniors) of urban population in the city of Thessaloniki, northern Greece, during the cold and the warm period of the year. Outdoor daily and hourly particle number doses in the different regions of the HRT, i.e., the extra-thoracic (ET), tracheobronchial (TB), and the acinar (AC) regions, were calculated by employing the Multiple-Path Particle Dosimetry (MPPD) model. Because of the absence of information being available for the hygroscopic properties of particles, three different particle hygroscopicity scenarios were considered: (i) non-hygroscopic (i.e., raw model estimations), (ii) nearly hydrophobic, and (iii) hygroscopic particles. When hygroscopic properties were considered, we found a remarkable reduction (up to ~ 55%) in the estimated total particle number doses in comparison to the non-hygroscopic particle scenario. Furthermore, we found that the size distribution pattern of the particle doses within the different parts of the HRT was strongly affected by particles' hygroscopic properties with the non-hygroscopic particle scenario significantly overestimating the particle doses in the sub-100-nm range, while underestimating the doses of larger particles. On the contrary, the deposition density appeared to be negligibly affected by the particles' hygroscopic properties, implying the existence of a possible threshold in the number of particles deposited per airway surface area. Similarly, the lobar particle number deposition fraction was unaffected by the hygroscopic properties of particles, as well as the ambient particle size distribution and the individuals' physiological parameters. The total particle number deposition doses estimated here are within the range of the corresponding values reported for other urban environments. It is hoped that our findings could contribute to better understanding of submicron particle exposure and add to the development of more sufficient methods to evaluate the related health impacts.

Deposition modeling of ambient aerosols in human respiratory system: Health implication of fine particles penetration into pulmonary region

In this study, we have monitored 1-h (afternoon) ambient concentrations of size-segregated particles by means of 12 channels aerosol spectrometer (PALAS; welas® 2000) over 130 days in one year (2015/2016) from a highly polluted and populated region (Kanpur) in central Indo-Gangetic Plain (IGP). Average mass concentrations of PM2.5 (fine) and PM10-2.5 (coarse) varied from ∼40–160 and 30–67 μg m−3, respectively. PM mass size distribution analysis revealed multi-modal peaks in monsoon (tri-modal: < 0.5; 1.4–1.8; 7.8 μm), post monsoon (tetra-modal: < 0.5; 1.4–1.8; 3.2; 7.8 μm), winter (tri-modal: < 0.5; 1.4–1.8; 5.8 μm) and summer (tetra-modal: < 0.5; 1.4–1.8; 3.2; 7.8 μm). The MMAD ± GSD were found to be 2.1 μm ± 3.0 (monsoon), 1.0 ± 3.0 μm (post monsoon), 1.1 μm ± 2.7 (winter) and 2.4 μm ± 2.9 (summer). A computational model (Multiple Path Particle Dosimetry: MPPD, v 2.11) analysis revealed total PM mass deposition in human respiratory airways (test subject: male adult) was 34.1 μg in monsoon, 64.5 μg in post monsoon, 40.6 μg in winter and 34.4 μg in summer. Coarse particles exhibited higher mass deposition fraction (84%) in HEAD (extrathoracic), whereas fine particles deposited significantly (33%) in PUL (pulmonary region). Intensification of biomass and biofuel burning emissions during post-monsoon and wintertime have implications to deeper penetration and higher mass deposition fraction of fine-particles in the PUL region. High PM concentration and its significant deposition in PUL region calls for immediate measures to be taken to improve regional air quality to reduce health hazards and disease burden for exposed population.

Second-hand aerosol from tobacco and electronic cigarettes: Evaluation of the smoker emission rates and doses and lung cancer risk of passive smokers and vapers

Smoking activities still represent the main, and preventable, cause of lung cancer risk worldwide. For this reason, a number of studies were carried out to deepen and better characterize the emission of cigarette-generated mainstream aerosols in order to perform an a-priori evaluation of the particle doses and related lung cancer risks received by active smokers. On the contrary, a gap of knowledge still exists in evaluating the dose and risk received by passive smokers in indoor private micro-environments (e.g. homes). For this purpose, in the present paper, an experimental campaign was performed to evaluate the exposure to second-hand aerosol from conventional and electronic cigarettes and to estimate the consequent dose received by passive smokers/vapers and the related lung cancer risk.Measurements of exposure levels in terms of particle number, PM10 and black carbon concentrations, as well as particle size distributions, were performed in a naturally ventilated indoor environment during smoking activities of tobacco and electronic cigarettes. The particle emission rates of smokers and vapers, for the different aerosol metrics under investigation, were evaluated. Moreover, for a typical exposure scenario, the dose received by the passive smokers/vapers in a naturally ventilated indoor micro-environment was estimated through a Multiple-Path Particle Dosimetry (MPPD) model able to assess the particle dose received in the different tracts of the respiratory systems. Furthermore, on the basis of scientific literature data about mass fraction of carcinogenic compounds contained in cigarette-emitted particles (i.e. Heavy Metals, Benzo-a-pyrene and nitrosamines) and the estimated doses, the excess life cancer risk (ELCR) for passive smokers/vapers was evaluated. Cumulative respiratory doses for passive smokers were up to 15-fold higher than for passive vapers. The ELCR for second-hand smokers was five orders of magnitude larger than for second-hand vapers.

Particle Size Distributions of Oxidative Potential of Lung-Deposited Particles: Assessing Contributions from Quinones and Water-Soluble Metals

Redox-active species in ambient particulate matter (PM) cause adverse health effects through the production of reactive oxygen species (ROS) in the human respiratory tract. However, respiratory deposition of these species and their relative contributions to oxidative potential (OP) have not been described. Size-segregated aerosols were collected during haze and nonhaze periods using a micro-orifice uniform deposit impactor sampler at an urban site in Shanghai to address this issue. Samples were analyzed for redox-active species content and PM OP. The average dithiothreitol (DTT) activity of haze samples was approximately 2.4-fold higher than that of nonhaze samples and significantly correlated with quinone and water-soluble metal concentrations. The size-specific distribution data revealed that both water-soluble OPvDTT (volume-normalized OP quantified by DTT assay) and OPmDTT (mass-normalized OP) were unimodal, peaking at 0.56-1 and 0.1-0.32 μm, respectively, due to contributions from accumulation-mode quinones and water-soluble metals. We further estimated that transition metals (mainly copper and manganese) contributed 55 ± 13% of the DTT activity while quinones accounted for only 8 ± 3%. Multiple-path particle dosimetry calculations estimated that OP deposition in the pulmonary region was mainly from accumulation-mode transition metals despite quinones having the highest DTT activity. This behavior is primarily attributed to the efficiency of deposition of transition metals in the pulmonary region being approximately 1.2-fold greater than that of quinones. These results reveal that accumulation-mode transition metals are significant contributors to the OP of deposited water-soluble particles in the pulmonary region of the lung.

Variation of particle number and mass concentration and associated mass deposition during Diwali festival

Diwali is one of the main festivals in India when firecrackers bursting lead to short term increase in particulate matter (PM) concentration in atmosphere. In this study, real time observations of size segregated particles number and mass concentration have been made during Diwali campaign in November 2015 at Kanpur. Results show that particle concentrations were highest during Post Diwali night as compared to Diwali night. This is attributable to build up of pollutants concentration from local and upwind region during Post Diwali. The PM2.5 mass concentration during Post Diwali was higher by a factor of 1.8 (day) and 1.3 (night) as compared to Pre Diwali. The average particle number concentration in ultrafine size (0.01 to 0.2μm) and cumulative particle size (0.01 to 1μm) during Post Diwali was higher by a factor of 6.8 and 3.7, respectively as compared to Pre Diwali nighttime. Size segregated PM data set for Pre Diwali, Diwali and Post Diwali periods were assessed for their deposition in human lung utilizing a computational model viz. MPPD (Multiple Path Particle Dosimetry). Results from lung deposition modeling have been systematically discussed. One of the major highlights of this study relates to penetration and significant deposition of fine particles in the pulmonary region during the study period in IGP. Our study, first of its own kind over Indian region, shows clearly the implications of air pollution on human health.

Characterization particulate matter from several Chinese cooking dishes and implications in health effects

Cooking fume produced by oil and food at a high temperature releases large amount of fine particulate matter (PM) which have a potential hazard to human health. This chamber study investigated particle emission characteristics originated from using four types of oil (soybean oil, olive oil, peanut oil and lard) and different kinds of food materials (meat and vegetable). The corresponding emission factors (EFs) of number, mass, surface area and volume for particles were discussed. Temporal variation of size-fractionated particle concentration showed that olive oil produced the highest number PM concentration for the entire cooking process. Multiple path particle dosimetry (MPPD) model was performed to predict deposition in the human respiratory tract. Results showed that the pulmonary airway deposition fraction was the largest. It was also found that particles produced from olive oil led to the highest deposition. We strongly recommend minimizing the moisture content of ingredients before cooking and giving priority to the use of peanut oil instead of olive oil to reduce human exposure to PM.

Inhalation exposure to particulate matter in a work environment of firefighters

The paper presents the results of research into the concentration of respirable and total particulate matter (PM) in a work environment of firefighters. Measurements were carried out from September 2017 to October 2017 during official capacity of firefighters, i.e. during firefighting, liquidation of other local hazards. The PM concentration was examined by the gravimetric method. For this purpose, two GilAir 3 aspirators and glass fibre filters were used. During the whole duty, the samplers were placed in the pockets of the uniform, while the measuring heads were harnessed to the collar of the uniform. The deposited mass of PM in the different regions of the respiratory tract was calculated using the Eulerian Multiple Path Particle Dosimetry model. Especially high PM concentrations were noted during firefighting, The PM deposits in the head, the trachea and bronchiolar and pulmonary alveolar regions were different depending on the action the firemen had to deal with.

Health impact assessment from building life cycles and trace metals in coarse particulate matter in urban office environments

This study intends to determine the health impacts from two office life cycles (St.1 and St.2) using life cycle assessment (LCA) and health risk assessment of indoor metals in coarse particulates (particulate matter with diameters of less than 10µm). The first building (St.1) is located in the city centre and the second building (St.2) is located within a new development 7km away from the city centre. All life cycle stages are considered and was analysed using SimaPro software. The trace metal concentrations were determined by inductively couple plasma-mass spectrometry (ICP-MS). Particle deposition in the human lung was estimated using the multiple-path particle dosimetry model (MPPD). The results showed that the total human health impact for St.1 (0.027 DALY m−2) was higher than St.2 (0.005 DALY m−2) for a 50-year lifespan, with the highest contribution from the operational phase. The potential health risk to indoor workers was quantified as a hazard quotient (HQ) for non-carcinogenic elements, where the total values for ingestion contact were 4.38E−08 (St.1) and 2.59E-08 (St.2) while for dermal contact the values were 5.12E-09 (St.1) and 2.58E-09 (St.2). For the carcinogenic risk, the values for dermal and ingestion routes for both St.1 and St.2 were lower than the acceptable limit which indicated no carcinogenic risk. Particle deposition for coarse particles in indoor workers was concentrated in the head, followed by the pulmonary region and tracheobronchial tract deposition. The results from this study showed that human health can be significantly affected by all the processes in office building life cycle, thus the minimisation of energy consumption and pollutant exposures are crucially required.

Particle size distributions of lead measured in battery manufacturing and secondary smelter facilities and implications in setting workplace lead exposure limits

ABSTRACTInhalation plays an important role in exposures to lead in airborne particulate matter in occupational settings, and particle size determines where and how much of airborne lead is deposited in the respiratory tract and how much is subsequently absorbed into the body. Although some occupational airborne lead particle size data have been published, limited information is available reflecting current workplace conditions in the U.S. To address this data gap, the Battery Council International (BCI) conducted workplace monitoring studies at nine lead acid battery manufacturing facilities (BMFs) and five secondary smelter facilities (SSFs) across the U.S. This article presents the results of the BCI studies focusing on the particle size distributions calculated from Personal Marple Impactor sampling data and particle deposition estimates in each of the three major respiratory tract regions derived using the Multiple-Path Particle Dosimetry model. The BCI data showed the presence of predominantly larger-sized particles in the work environments evaluated, with average mass median aerodynamic diameters (MMADs) ranging from 21–32 µm for the three BMF job categories and from 15–25 µm for the five SSF job categories tested. The BCI data also indicated that the percentage of lead mass measured at the sampled facilities in the submicron range (i.e., <1 µm, a particle size range associated with enhanced absorption of associated lead) was generally small. The estimated average percentages of lead mass in the submicron range for the tested job categories ranged from 0.8–3.3% at the BMFs and from 0.44–6.1% at the SSFs. Variability was observed in the particle size distributions across job categories and facilities, and sensitivity analyses were conducted to explore this variability. The BCI results were compared with results reported in the scientific literature. Screening-level analyses were also conducted to explore the overall degree of lead absorption potentially associated with the observed particle size distributions and to identify key issues associated with applying such data to set occupational exposure limits for lead.

Second-hand smoke generated by combustion and electronic smoking devices used in real scenarios: Ultrafine particle pollution and age-related dose assessment

Aerosol measurements were carried out in a model room where both combustion (conventional and hand-rolled cigarettes, a cigar and tobacco pipe) and non-combustion (e-cigarette and IQOS®) devices were smoked. The data were used to estimate the dose of particles deposited in the respiratory systems of individuals from 3months to 21years of age using the multiple-path particle dosimetry (MPPD) model. Regardless of the smoking device, the highest doses were received by infants, which reached 9.88×108particles/kg bw during a cigar smoking session. Moreover, 60% to 80% of the particles deposited in the head region of a 3-month-old infant were smaller than 100nm and could be translocated to the brain via the olfactory bulb. The doses due to second-hand smoke from electronic devices were significantly lower, below 1.60×108particles/kg bw, than those due to combustion devices. Dosimetry estimates were 50% to 110% higher for IQOS® than for e-cigarettes.

Derivation of health effect factors for nanoparticles to be used in LCIA

In this paper, we discuss the derivation of respiratory health effect factors (HEFs) for use in Life Cycle Impact Assessment (LCIA) for five nanoparticles: nanosilver, nano TiO2, carbon black, high-aspect ratio, rigid MWCNT and flexible MWCNT. For this purpose, we applied the methodology of USEtox™, a consensus model to calculate human toxicity and ecotoxicity characterization factors. In view of the available data, the non-carcinogenic HEFs for carbon black and TiO2 can be attributed the recommended status. For MWCNT and nanosilver the non-carcinogenic HEFs should be awarded the indicative status due to the minimal effects observed in the animal studies. All carcinogenic HEFs are currently labelled as indicative since there is no consensus with respect to the human relevance of the overload mechanism of carcinogenicity observed in rats exposed to poorly soluble particles (carbon black, flexible MWCNT and TiO2), whereas for high-aspect ratio, rigid MWCNT, the extrapolation from asbestos carcinogenicity introduces uncertainty. For nanosilver no carcinogenic HEF could be derived.The present study clearly demonstrates the difficulties associated with the derivation of HEFs for the nanomaterials considered, in particular in the USEtox™ framework for comparative risk assessment, and makes recommendations to overcome them:•Nanoparticles for which a dose metric other than its mass is relevant for their toxicity require ‘normalisation’ to the mass metric. Adaptation of USEtox™ to accommodate other dose metrics than mass intake is therefore recommended.•Simplified estimates of deposited and retained dose are currently needed, ignoring particle size distribution dependency. Therefore, it is recommended to include kg deposited and kg retained as dose parameters for HEFs in USEtox™ and to link USEtox™ to the Multiple Path Particle Dosimetry model to convert kg intake to these dose parameters.•Establishment of the Point of Departure (PoD) for the derivation of the HEFs and the extrapolation factors to be used is recommended through consensus building. Although the ED50 is preferred as the PoD from the perspective of comparative risk assessment in LCA, for some nanoparticles, other PoDs could be considered when the dose-response data are limited.•Overall, the assessed nanoparticles are likely to be more toxic than most bulk chemicals regarding non-carcinogenic effects. However, the results of LCIA based on these HEFs must be interpreted with the necessary constraints and reservations due to the large uncertainty involved.

Modeled Deposition of Fine Particles in Human Airway in Northern Suburb of Nanjing

The particles number concentrations were determined by Wide-range Particle Spectrometer (WPS) in northern suburb of Nanjing in January and April 2015. The information of size distributions was applied in the multiple-path particle dosimetry model (MPPD) v.3.04 to quantify deposition fractions (DF) and number concentration (NC) depositions of fine particles in different regions of human airway, at different air quality levels, at rest and exercise. DF of nucleation mode and Aitken mode at rest and exercise were similar, while DF of accumulation mode at exercise was 2.49 times of that at rest. DF of nucleation mode and Aitken mode in pulmonary (PUL) was the highest, about 48.17% of total deposition fractions (TDF) at rest and 54.23% of TDF at exercise. DF of accumulation mode in head was the highest, about 41.23% of TDF at rest and 80.47% of TDF at exercise. The particle NC deposition in human airway in winter was lower than that in spring, and the total NC deposition in 3 regions was in the order of PUL > tracheobronchial(TB) > head. Compared with resting, nucleation mode deposition in PUL and accumulation mode deposition in TB and head increased at exercise. The worse the air quality, the higher the deposition growth rate of exercising to resting in head. DF difference among regions was mainly due to the different physiological parameters, while NC deposition difference was mainly due to the different particle NC in the local environment.

PAHs in Size Fractionate Mainstream Cigarette Smoke, Predictive Deposition and Associated Inhalation Risk

ABSTRACTSize fractionated mainstream cigarette smoke (MCS) samples were collected with variable configuration cascade impactor (VCCI). Samples were extracted ultrasonically and analysis of sixteen priority polycyclic aromatic hydrocarbons (PAHs) was performed using high performance liquid chromatography (HPLC) coupled with UV-visible detector. Identification of PAHs were also carried out using gas chromatography coupled with mass spectrometry (GC-MS) technique. Data of size fractionate PAHs in MCS were used to calculate size dependent deposition in different compartment of human respiratory tract using multiple path particle dosimetry (MPPD) model. All brand cigarette smoke showed similar trends of particle mass and PAHs size distribution peaked at two sizes 0.3–0.1 µm and 0.75–1.13 µm aerodynamic diameter. All tested brands of MCS recorded around 48.75% of two and three-ring PAHs, 23 to 25% four-ring PAHs and 26–27% five and higher rings PAHs of total analyzed PAHs. Benzo[a]pyrene equivalent (B[a]Peq) PAHs emission in MCS was found to be 110 ± 12 (µ ± 1σ) ng per cigarette for tested brands. Total deposition fraction in respiratory tract was found to be 0.69 ± 0.26 for tested size ranges. Average 5th and 95th percentile values of incremental lifetime cancer risk (ILCR) for smoker due to PAHs exposure were found to be 1.3 × 10–5 to 3.9 × 10–5 respectively for tested cigarette brands.

Inhalation Exposure to PM-Bound Polycyclic Aromatic Hydrocarbons Released from Barbecue Grills Powered by Gas, Lump Charcoal, and Charcoal Briquettes.

The present study seeks to define the possible cancer risk arising from the inhalation exposure to particle (PM)-bound polycyclic aromatic hydrocarbons (PAHs) present in barbecue emission gases and to compare the risk depending on the type of fuel used for grill powering. Three types of fuel were compared: liquid propane gas, lump charcoal, and charcoal briquettes. PM2.5 and PM2.5-100 were collected during grilling. Subsequently, 16 PAHs congeners were extracted from the PM samples and measured quantitatively using gas chromatography. The content of PM-bound PAHs was used to calculate PAHs deposition in the respiratory tract using the multiple path particle dosimetry model. Finally, a probabilistic risk model was developed to assess the incremental lifetime cancer risk (ILCR) faced by people exposed to PAHs. We found a distinctly greater PAHs formation in case of grills powered by charcoal briquettes. The summary concentration of PAHs (Σ16PAH) ranged from <0.002 μg/m3 (gas grill) to 21.52 μg/m3 (grill powered by briquettes). Daily exposure of a grill operator, while grilling meat, to PM2.5-bound PAHs, adjusted to benzo[a]pyrene toxicity equivalent (BaPeq), was 326.9, 401.6, and 0.04 ng/d for lump charcoal, charcoal briquettes, and gas powered grill, respectively. Exposure to PAHs emitted from charcoal briquettes was four orders of magnitude greater than that for gas grill. The ILCR followed a log-normal distribution, with a geometric mean of 8.38 × 10-5 for exposure to PM2.5-bound PAHs emitted from gas grills unloaded with food and as high as 8.68 × 10-1 for the grills loaded with food over charcoal briquettes. The estimated cancer risk for people who would inhale barbecue particles for 5 h a day, 40 days a year exceeds the acceptable level set by the U.S. Environmental Protection Agency. We conclude that the type of heat source used for grilling influences the PM-bound PAHs formation. The greatest concentration of PAHs is generated when grilling over charcoal briquettes. Loading grills with food generates conspicuously more PAHs emissions. Traditional grilling poses cancer risk much above the acceptable limit, as opposed to much less risk involving gas powered grills.

Fine and ultrafine particle doses in the respiratory tract from digital printing operations.

In this study, we report for the first time particle number doses in different parts of the human respiratory tract and real-time deposition rates for particles in the 10nm to 10μm size range emitted by digital printing operations. Particle number concentrations (PNCs) and size distribution were measured in a typical small-sized printing house using a NanoScan scanning mobility particle sizer and an optical particle sizer. Particle doses in human lung were estimated applying a multiple-path particle dosimetry model under two different breathing scenarios. PNC was dominated by the ultrafine particle fractions (UFPs, i.e., particles smaller than 100nm) exhibiting almost nine times higher levels in comparison to the background values. The average deposition rate fοr each scenario in the whole lung was estimated at 2.0 and 2.9×107 particles min-1, while the respective highest particle dose in the tracheobronchial tree (2.0 and 2.9×109 particles) was found for diameter of 50nm. The majority of particles appeared to deposit in the acinar region and most of them were in the UFP size range. For both scenarios, the maximum deposition density (9.5×107 and 1.5×108 particles cm-2) was observed at the lobar bronchi. Overall, the differences in the estimated particle doses between the two scenarios were 30-40% for both size ranges.

A new method for measuring lung deposition efficiency of airborne nanoparticles in a single breath.

Assessment of respiratory tract deposition of nanoparticles is a key link to understanding their health impacts. An instrument was developed to measure respiratory tract deposition of nanoparticles in a single breath. Monodisperse nanoparticles are generated, inhaled and sampled from a determined volumetric lung depth after a controlled residence time in the lung. The instrument was characterized for sensitivity to inter-subject variability, particle size (22, 50, 75 and 100 nm) and breath-holding time (3–20 s) in a group of seven healthy subjects. The measured particle recovery had an inter-subject variability 26–50 times larger than the measurement uncertainty and the results for various particle sizes and breath-holding times were in accordance with the theory for Brownian diffusion and values calculated from the Multiple-Path Particle Dosimetry model. The recovery was found to be determined by residence time and particle size, while respiratory flow-rate had minor importance in the studied range 1–10 L/s. The instrument will be used to investigate deposition of nanoparticles in patients with respiratory disease. The fast and precise measurement allows for both diagnostic applications, where the disease may be identified based on particle recovery, and for studies with controlled delivery of aerosol-based nanomedicine to specific regions of the lungs.

Aerodynamic particle size distribution and dynamic properties in aerosols from electronic cigarettes

Aerodynamic Particle Size Distribution (APSD) is an important factor governing if aerosols can be inhaled to different parts of a human's respiratory system. To understand the APSD of the aerosol produced from several brands of E-cigarettes, measurements using the Next Generation Pharmaceutical Impactor (NGI) were performed.The NGI impactor was operated at two different temperature conditions, ambient room temperature condition (20–25°C) and in a cold condition (4–8°C). The relative humidity (RH) in the latter case, cooled impactor, was close to 100%, similar to the human's respiratory system. Obtained Mass Median Aerodynamic Diameters (MMAD) for the investigated electronic cigarettes were in the range 0.5–0.9µm. The different NGI temperature conditions had a significant effect on the result and this is probably due to dynamic processes during the aerosol transport in the NGI pass ways.For each NGI measurements performed the nicotine present in both the droplets and in the gaseous phase were measured. This is different from the previously published data using physical aerosol sizing techniques (such as Scanning Mobility Particle Sizer, SMPS), where obtained droplet sizes is a result of all chemical components in the aerosol, not only nicotine. In principle, it could be only excipients in the droplets and all nicotine in gaseous phase. Thus, impactor and a gas trap with nicotine specific quantification is a good complement for more thorough understanding of droplet size distributions of E-cigarette.The APSD in vitro data was used in theoretical modeling using the Multiple-Path Particle Dosimetry Model (MPPD v 2.11), for estimation of the lung deposition. Using the model it was estimated that 75–90% of the nicotine droplets will be exhaled and 10–25% deposited in the respiratory system. However, when an aerosol is inhaled to a human's respiratory system it will be diluted and the evaporation of nicotine will increase. This will lead to overestimation of the fraction of exhaled nicotine using the MPPD model.