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The particle number concentration (PNC), particulate matter (PM1) and black carbon (BC) mass concentration limits are not available from standard air quality monitoring networks as well as for indoor level standards in many countries. Total personal exposure is often disproportionately affected by the relatively short amount of time spent in office spaces and commuting trips. In this study, real-time measurements of PNC, PM1, and BC mass concentrations in the office and during commuting trips were performed to assess real-time employee personal exposure. Urban environments are very complex due to the different emission sources and their emission activities; therefore, a combination of mobile and stationary measurements allows for a better understanding of their dynamics and employee exposure, constituting a better predictor of health effects. Mobile measurements at the street level showed that the BC mass concentrations were the highest during peak hours, reaching up to 7.14 µg/m3 at hotspots. The hourly mean BC mass concentration in March 2022 at the urban background station ranged from 0.30 to 9.01 µg/m3, with traffic-related BC (BCtr) accounting for 66% of the total BC mass concentration. The highest minute deposition dose of BC (MDDBC) occurred during the morning rush hour at 53 ng/min and in the evening at 26 ng/min. These findings reveal the impact of traffic exhaust emissions on aerosol particles, particularly on fine particles. Marked differences were found between the MDDBC in the office and the vehicle micro-environment. The deposition dose in the office micro-environment was 11 ng/min. The results from the multi-path particle dosimetry model indicate that almost half of the inhaled BC mass 39.2% was deposited in the lowest part of the respiratory system, the lung-pulmonary region. [ABSTRACT FROM AUTHOR]

This study correlates computational predictions with in vivo and in vitro experimental results of inhaled fine and ultrafine particulate matter (PM) transport, dissemination, and deposition in the human respiratory airways. Epidemiological studies suggest that workplace exposure to anthropogenic pollutant PMs is a risk factor for increased susceptibility to acute bronchopulmonary illnesses. However, investigations on detailed human inhalation and PM transport processes are restrictive from time, cost, and ethical perspectives. Computational simulation based on the Multiple Path Particle Dosimetry (MPPD) model was employed to quantify the risks associated with workplace exposure of these PMs. Here, the physical, mechanical, and electrical properties of PMs of carbon black (CB) and ultrafine particles (UFPs) from wire-cut electrical discharge machining (WEDM), with mass median aerodynamic diameter (CMAD) in the range of 1 nm to 1000 nm, were used as input parameters of MPPD. Additionally, it mimicked occupational workers’ age, body mass index, and oronasal-combinational nose and mouth breathing exposure time. The deposition results were compared with several vivo and in vitro experimental data reported in the literature, and satisfactory agreements were found. For example, a total lung dose of CB-PMs of 100 nm is the highest (28%), while a 380 nm dose is the lowest (15%). Afterward, deposition increases with particle size, reaching 26% for 1000 nm. In the case of WEDM-UFPs, about 98% of all 1.0 nm inhaled particles remain in the lung. Subsequently, the deposition dose decreases with the particle size and reaches up to 28% for 100 nm particles. Approximately 51% of deposited WEDM-UFPs are of CMAD ≤ 5 nm. The images of lung geometry also observed the maximum deposited mass and mass flux rate in the head, tracheobronchial, and pulmonary airways. [ABSTRACT FROM AUTHOR]

Background: Quantifying the dose and distribution of tobacco smoke in the respiratory system is critical for understanding its toxicity, addiction potential, and health impacts. Epidemiologic studies indicate that the incidence of lung tumors varies across different lung regions, suggesting there may be a heterogeneous deposition of smoke particles leading to greater health risks in specific regions. Despite this, few studies have examined the lobar spatial distribution of inhaled particles from tobacco smoke. This gap in knowledge, coupled with the growing popularity of little cigars among youth, underscores the need for additional research with little cigars. Results: In our study, we analyzed the lobar deposition in rat lungs of smoke particles from combusted regular and mentholated Swisher Sweets little cigars. Twelve-week-old male and female Sprague-Dawley rats were exposed to smoke particles at a concentration of 84 ± 5 mg/m3 for 2 h, after which individual lung lobes were examined. We utilized Inductively Coupled Plasma Mass Spectrometry to quantify lobar chromium concentrations, serving as a smoke particle tracer. Our findings demonstrated an overall higher particle deposition from regular little cigars than from the mentholated ones. Higher particle deposition fraction was observed in the left and caudal lobes than other lobes. We also observed sex-based differences in the normalized deposition fractions among lobes. Animal study results were compared with the multi-path particle dosimetry (MPPD) model predictions, which showed that the model overestimated particle deposition in certain lung regions. Conclusions: Our findings revealed that the particle deposition varied between different little cigar products. The results demonstrated a heterogenous deposition pattern, with higher particle deposition observed in the left and caudal lobes, especially with the mentholated little cigars. Additionally, we identified disparities between our measurements and the MPPD model. This discrepancy highlights the need to enhance the accuracy of models before extrapolating animal study results to human lung deposition. Overall, our study provides valuable insights for estimating the dose of little cigars during smoking for toxicity research. [ABSTRACT FROM AUTHOR]