Extrathoracic Region Research Articles

Association between respiratory tract deposited dose of size-segregated PM and FeNO based on individual exposure assessment for Korean children

FeNO (fractional exhaled nitric oxide) is a crucial marker to understand children's respiratory diseases such as asthma, and severity may vary depending on PM diameter and respiratory tract region. This study investigates the relationship between size-segregated respiratory deposited PM dose and FeNO for children. Size-segregated PM (PM1.0, PM1.0–2.5, and PM2.5–10.0) and FeNO were measured for eighty children based on individual exposure assessment in five consecutive days. Individual physical activity was measured by an accelerometer device. Accordingly, a dosimetry model estimated the respiratory deposited dose by PM diameter in the extrathoracic (ET), tracheobronchial (TB), and pulmonary (PUL) regions. A linear mixed model (LMM) with distributed lag non-linear model (DLNM) was used for analysis. The effects of home environment and traffic-related factors were also examined for sensitivity analysis. We found that IQR increases of PM2.5–10.0 and PM1.0 were associated with 15.1 % (95 % CI: 3.5, 28.1) and 15.9 % (95 % CI: 2.7, 30.9) FeNO increase in respiratory Total region in 0–12 h lag. In cumulative lag 0–24 h, PM1.0 was only associated with FeNO increase: 16.6 % (95 % CI: 1.5, 34.1) in total region. No association was observed in lag 12–24 h. PM2.5–10.0 was related to short-term airway inflammation in the upper respiratory tract whereas PM1.0 has a cumulative effect on both the upper and lower respiratory tract. In sensitivity analysis, PM2.5–10.0 was associated with a 0–12 h lag, whereas both PM2.5–10.0 and PM1.0 were associated with a cumulative lag of 0–24 h. Both home environment and traffic-related factors showed a synergetic effect with PM1.0 in short-term exposure and an antagonistic effect with PM2.5–10.0 in long-term exposure. This study highlights that airway inflammation depends on PM sizes, exposure durations, and respiratory tract regions.

Estimation and analysis of S values for 131I using paediatric mesh type reference computational phantoms

This study examines the effect of paediatric mesh-type reference computational phantoms on organSvalues resulting from radioiodine (131I) intake. Using Geant4, we estimated131ISvalues for 30 radiosensitive target tissues due to emission from the thyroid (Target ← Thyroid) in these phantoms. Our results show thatSvalues differ between male and female phantoms of the same age andSvalues also decrease as phantom age increases. The male-to-femaleSvalue ratio typically varies within 10%, with larger differences observed for the esophagus, extra-thoracic regions, muscles, bladder, and sex organs. On average,Svalues for mesh phantoms are approximately 17% higher than those for voxel phantoms, with larger discrepancies for organs remodelled separately in mesh phantoms. The study provides organSvalues for the paediatric population due to131I exposure from the thyroid, based on the reference mesh-type computational phantoms, enhancing organ dose estimation in emergency situations and during radioiodine treatment.

The fate of airborne microfibers in the human respiratory tract in different microenvironments

Αirborne microplastics (MPs) are considered an important exposure hazard to humans, especially in the indoor environment. Deposition and clearance of MPs in the human respiratory tract (HRT) was investigated using the ExDoM2 dosimetry model, modified to incorporate the deposition and clearance of MPs fibers. Fiber deposition was calculated via the fiber equivalent aerodynamic diameter determined using their properties such as size, density and dynamic shape factor. Scenario simulations were performed for elongated particles of cylindrical (base) diameters 1 μm and 10 μm and aspect ratios (ratio of fiber length to base diameter) 3, 10 and 100. Modelling results showed that the highest fiber deposition occurred in the extra-thoracic region due to large particles (fiber cylindrical diameter dp > 0.1 μm), whereas particle length (via the aspect ratio) had an influence mainly on smaller base-diameter fibers (dp < 0.1 μm) that deposited predominantly in the alveolar region. The ExDoM2 dosimetry model was also used to calculate fiber deposition in the HRT using experimental data for microplastic fiber and fragment concentrations in different microenvironments. The highest deposited number dose (220 fibers) after a 24-hour exposure was calculated in the microenvironment (bus) that had the highest fiber concentration (17.3 ± 2.4 fibers/m3). After clearance, the majority (66.4 %) of the average deposited fiber mass was transferred from the respiratory tract to the esophagus via mucociliary clearance, 32.6 % was retained in the respiratory tract, 1 % passed into the blood, and a very small amount (0.0004 %) was transferred to the lymph nodes.

A model study on the effect of human's height variability in particle deposition and retained dose in the respiratory tract.

The objective of the current study was to investigate the impact of human's height variability to the deposition percentage, the deposited and the retained dose of particulate matter in the respiratory tract. In addition, the dose to the oesophagus, blood and lymph nodes was evaluated after particle clearance. A methodology which correlates anatomical and physiological parameters with height was adopted into an existing particle dosimetry model (Exposure Dose Model 2, ExDoM2). Model results showed that deposition of particles with aerodynamic diameter (dae) ranging from 0.001 to 10 μm depends on the competition between anatomical/physiological parameters, with the maximum effect induced from height variability to be observed for particles in the size range of 0.30 μm <dae <1.5 μm. Specifically, a decrease in the subject's height by 100 cm (from 175 to 75 cm) caused a 60.5 ± 6.8% increase in the total deposition percentage during light exercise. Contrarily, an increase in the subject's height by 100 cm (from 75 to 175 cm) caused a 376% increase in the daily deposited dose of PM10 in the respiratory tract. Investigating the inter-subject variability of PM10 dose showed that the extrathoracic region was characterized by lower variability (10.0%) compared to the thoracic region (16.2%). After clearance, the highest variability was observed for blood (15.7%), followed by the respiratory tract (12.1%), lymph nodes (10.4%) and oesophagus (10.1%). Results of the current study highlight the impact induced by incorporating height to scale the inter-subject variability in particle deposition and dose in the human body.

Recurrent infiltrative lipoma of the thoracic and abdominal wall in a young dog

AbstractA 1‐year and 8‐month‐old neutered male English Cocker Spaniel was presented with a large subcutaneous mass in the right ventrocaudal thoracic region, which was firmly adhered to the deeper tissues. An adipose tissue mass had been excised from the same region 12 months previously. Investigation included a computed tomography scan of the thorax and abdomen, which revealed a fat‐attenuating mass. The mass was both extra and intrathoracic and encompassed the ventrocaudal thoracic wall and infiltrated surrounding musculature. Marginal en bloc resection was performed. A right intercostal thoracotomy allowed resection of the intercostal component. Postoperative radiation therapy was recommended; however, it was declined by the owners. Nine months after surgery, recurrence of the mass was identified; however, the mass was small (2 cm diameter) and present within the extrathoracic subcutaneous region. The dog was reported to be clinically well with no associated clinical signs. Further treatment inclusive of revision surgery and postoperative radiation was declined.

Particulate matter deposition in the human respiratory system: A health risk assessment at a technical university

Introduction: This study quantified Particulate Matter (PM) deposition and its clearance in the Human Respiratory Tract (HRT) at different microenvironments of a university. The university is located adjacent to the National Highway (NH 334) and main bus stop of the city, thus highly affected by PM pollution.&#x0D; Materials and methods: The deposition calculations were performed using a widely accepted MPPD 3.04 model. Three seasons (summer, winter and monsoon), seven microenvironments (including three Lecture Hall Complexes (LHCs), a library, two laboratories and outdoor), and different activity patterns associated with each microenvironment were considered.&#x0D; Results: The deposited mass of coarse fraction (PM2.5-10) in different HRT regions follows the order: pulmonary (0.5%)&lt;tracheobronchial (2%)&lt;head&#x0D; (or extrathoracic region) (97.5%). In the case of lobar region, because of the larger volume of lower lobes, they received higher deposition (53%) than the middle (8%) and upper lobes (39%). Further, the sitting activity level was found to be most critical for lobar deposition. The total deposited mass in the HRT was maximum outdoors and minimum at the library. The difference in winter and monsoon deposition was 100% for PM2.5-10, 75% for PM1-2.5 and 126% for PM1. The clearance rate of PM1 is such that 1.5 % of particles in the tracheobronchial and 64% in the pulmonary region remained even after six months.&#x0D; Conclusion: The results implied that physical activity levels, mode of inhalation and particle size significantly influence regional deposition. For instance, heavy exercise causes greater deposition in the head region, whereas sitting activity contributes to higher pulmonary and tracheobronchial deposition.

Effects of breathing variables on modelled particle lung deposition at physical activity for children and adults

AbstractThe respiratory tract deposited fraction (DF) is the link between exposure and health effects of airborne particles. Here, we investigate how breathing pattern alterations at increasing physical activity affect DF in different regions of the respiratory tract and compare DF between adults and children (5 and 10 years old). We performed a literature review on the alteration of tidal volume with minute ventilation at increasing physical activity and used the results to model the size resolved (0.001–10 µm) DF, primarily using the deposition models from NCRP and Yeh and Schum (1980), but also MPPD. We found a shift in the deposited size distribution with increasing physical activity—DF of ultrafine particles increased in the alveolar region and decreased in the other regions, while DF of coarser particles decreased in the alveolar region and increased in the extra-thoracic region. Children had a 10–20% higher DF of ultrafine particles in the alveolar region compared to adults. We also present parametrizations of the daily average size resolved (0.005–5 µm) DF, accounting for varying physical activity throughout the day and oral/nasal breathing. These can be applied to any size distribution to estimate deposited doses. We found that deposited mass and number doses were more than twice as high for 5-year-olds compared to adults when normalized for body weight, primarily caused by their higher weight normalized minute ventilation. This demonstrates the importance of studying children’s exposure to air pollution and not only rely on data from adults.

Assessment of organ doses, peak skin doses and effective doses in patients undergoing anterior cervical discectomy and fusion utilising VirtualDose-IR software.

In this study, the effect of patient- and procedure-related parameters on organ doses (ODs), peak skin dose (PSD) and effective dose (E) during anterior cervical discectomy and fusion (ACDF) was evaluated. Patient- and procedure-related parameters, as well as fluoroscopy time, kerma-area product (KAP), cumulative air-kerma (Kair) and incident Kair, were analysed for 50 ACDF procedures performed with a mobile C-arm. These parameters were inserted in VirtualDose-IR software implementing sex-specific and body mass index (BMI)-adjustable anthropomorphic phantoms to calculate OD, PSD and E. The BMI, gender and type of implants did not significantly affect KAP, incident Kair, PSD and E. However, the type of fusion significantly affected the E. The single fusions in C5/C6 resulted in significantly higher KAP, incident Kair and E than C4/C5 levels, while those performed in C6/C7 resulted in significantly higher E and PSD than C4/C5 levels. The thyroid, oesophagus and salivary glands received the largest doses in all groups studied. The BMI did not significantly affect ODs. The salivary glands absorbed significantly higher doses in males than females, while the extrathoracic region's dose significantly increased for multi- than single-level fusions. The fusions in C6/C7 resulted in significantly higher oesophagus and thyroid doses than C3/C4 and C4/C5 levels, as well as fusions performed in C5/C6 compared with C4/C5 levels. The data presented here could be used by the neurosurgeons as a comparator for future studies in optimising radiation protection during ACDF procedures in the operating theatre by keeping the ODs, PSD and E as low as reasonably practicable.

Development of Respiratory Tract Organs for ICRP Pediatric Mesh-type Reference Computational Phantoms.

As part of the activities of the International Commission on Radiological Protection (ICRP) Task Group 103, the present study developed a new set of respiratory tract organs consisting of the extrathoracic, bronchial, bronchiolar, and alveolar-interstitial regions for newborn, 1-, 5-, 10-, and 15-y-old males and females for use in pediatric mesh-type reference computational phantoms. The developed respiratory tract organs, while preserving the original topologies of those of the pediatric voxel-type reference computational phantoms of ICRP Publication 143, have improved anatomy and detailed structure and also include μm-thick target and source regions prescribed in ICRP Publication 66. The dosimetric impact of the developed respiratory tract organs was investigated by calculating the specific absorbed fraction for internal electron exposures, which were then compared with the ICRP Task Group 96 values. The results showed that except for the alveolar-interstitial region as a source region, the pediatric mesh phantoms showed larger specific absorbed fractions than the Task Group 96 values. The maximum difference was a factor of ~3.5 for the extrathoracic-2 basal cell and surface as target and source regions, respectively. These results reflect the differences in the target masses and geometry caused by the anatomical enhancement of the pediatric mesh phantoms. For the alveolar-interstitial region as a source region, the pediatric mesh phantoms showed larger values for low energy ranges and lower values with increasing energies, owing to the differences in the size and shape of the alveolar-interstitial region.

Application of heliox for optimized drug delivery through respiratory tract

Understanding the transportation and deposition (TD) of inhaled particles in the upper respiratory tract is crucial for predicting health risks and treating pulmonary diseases. The available literature reports highly turbulent flow in the extrathoracic (ET) region during normal breathing, which leads to higher deposition of the drug aerosol in this region. To improve the targeted deposition of inhaled drugs, in the tracheobronchial airways, it is essential to understand the flow and particle transport dynamics and reduce the turbulence behavior at the ET region. The less-dense heliox gas could reduce the turbulence behavior at the ET; however, the knowledge of heliox inhalation therapies in drug aerosol TD remains underachieved to realize the full potential for assisted breathing and drug delivery. Additionally, the impact of the inhalation of heliox mixed with other gases on particle deposition is missing in the literature. Therefore, this study aims to develop a mixture model to advance the knowledge of inhalation therapy. A heliox (78% helium and 22% oxygen) and a mixture of heliox and air are used to understand the flow behavior and particle TD in airways. The impact of different inhalation and Stokes numbers on the deposition efficiencies in the ideal and age-specific upper airways is studied. The study reports that less-dense heliox gas has lower turbulence intensity and results in lower deposition efficiency in the G3–G5 lung airways compared to air and mixture inhalations. Moreover, slightly higher deposition efficiencies during mixture inhalation as compared to air inhalation are found in the upper airways. The deposition patterns of different inhalations obtained in this study could help improve targeted drug delivery into the upper and deeper lung airways.

Size distribution and lung-deposition of ambient particulate matter oxidative potential: A contrast between dithiothreitol and ascorbic acid assays

Particulate matter (PM) inhaled into human lungs causes oxidative stress and adverse health effects through antioxidant depletion (oxidative potential, OP). However, there is limited knowledge regarding the association between the lung-deposited dose (LDD) of PM and OP in extrathoracic (ET), tracheobronchial (TB), and pulmonary (P) regions of human lungs. Dithiothreitol (DTT) and ascorbic acid (AA) assays were employed to measure the OP of PM size fractions to investigate OP distribution in human lungs and identify the chemical drivers. Quasi-ultrafine particles (quasi-UFP, ≤0.49 μm) exhibited high OP deposition in the TB and P regions, while coarse particles (CP, ≥3.0 μm) dominated in the ET region. A plot of extrinsic (per air volume) and intrinsic (per PM mass) OP versus LDD revealed that the OP for fine and coarse particles was greatest in the ET region, whereas the OP of quasi-UFP was greatest in alveoli. The study also demonstrated that extrinsic OP and PM doses are not strongly related. The decline in OP with increasing PM dose reveals the need for further investigation of the antagonistic effects of the chemical compositions. Overall, the results presented herein help address the gap in knowledge regarding the association between the OP and LDD of ambient particles in specific regions of human lungs.

Changes induced in the human respiratory tract by chronic cigarette smoking can reduce the dose to the lungs from exposure to radon progeny

Chronic cigarette smoking leads to changes in the respiratory tract that might affect the dose received from exposure to radon progeny. In this study, changes induced by cigarette smoking in the respiratory tract were collected from the literature and used for calculation of the dose received by the lungs and organs outside the respiratory tract. Morphological and physiological parameters affected by chronic smoking were implemented in the human respiratory tract model (HRTM) used by the International Commission of Radiological Protection (ICRP). Smokers were found to receive lung doses 3% smaller than the ICRP reference worker (non-smoking reference adult male) in mines and 14% smaller in indoor workplaces and tourist caves. A similar dose reduction was found for the extrathoracic region of the HRTM. Conversely, kidneys, brain, and bone marrow of smokers were found to receive from 2.3- up to 3-fold of the dose received by the respective organ in the ICRP reference worker, although they remained at least two orders of magnitude smaller than the lung dose. These results indicate that the differences in the lung dose from radon progeny exposure in cigarette smokers and non-smokers are smaller than 15%.

90 Bioaerosol Exposure in Automated and Traditional Waste Sorting Plants

Abstract The waste management sector takes a central part in the transition towards circular economy and is subject to technological progress and the implementation of new work operations. Traditional waste collection and processing systems are characterized by numerous tasks that favour waste workers’ exposure to bioaerosols, whereas exposure in modern automated waste sorting plants remains elusive. Moreover, there is still a lack of health-risk based exposure limits for most components contained in bioaerosols. We investigated occupational exposure to bioaerosols in traditional and automated waste sorting plants. The results revealed significant differences in various exposure levels, such as total dust (GM automated: 0.34 mg/m3, GM manual: 0.66 mg/m3), endotoxins (GM automated: 51 EU/m3, GM manual: 32 EU/m3) and microorganisms between and within type of plant. An assessment of the composition of air-borne fungal particles (FESEM based immunodetection method) showed significantly increased levels of fungal spores at automated waste sorting plants (GM automated: 1.2 × 105 spores/m3, GM manual: 2.1 × 104 spores/m3). Elevated total dust levels and concentrations of submicronic fungal fragments were significantly correlated to the occurrence of symptoms of the extrathoracic region, such as congested nose, in exposed workers. The results of this study showed high variation in exposure levels between and within type of waste sorting plant, as well as seasonal variation for some parameters, such as total dust and endotoxins. This indicates that Norwegian waste workers are potentially exposed to high levels of dust and microorganisms that may cause adverse health effects in receptible individuals.

Neumomediastino asociado a neumonía por COVID-19

Neumomediastino asociado a neumonía por COVID-19

The Influence of Adopting New Reference Breathing Parameters on ICRP66 Model on the Regional Deposition of the Inhaled Attached Radon-222 Daughters Within the Human Airways.

The radiation dose from internal radiation exposure is difficult to measure directly and hence different lung models were developed. The dose on the lung is the result of the regional deposition of aerosols carrying radon daughters in the respiratory tract. Deposition of aerosols can be take place during inhalation and exhalation in the 5 regions of the respiratory tract due to variation of aerosol sizes and other biological factors such as breathing rate. In this paper, a modified breathing rate is instead applied on the assumptions developed by the ICRP66 model to analyze the regional deposition of radioactive aerosols and a comparison has been made with the result of ICRP66 model deposition. According to the result, as the diameter of aerosols increases from 1 to 10 μm, the percentage deposition fraction in extrathoracic regions, in ET1 region increases from 6.53% to 48.43% and in ET2 region increases from 7.3% to 50.33%. The aerodynamic deposition of the attached fraction of radon aerosols along the bronchial regions (bronchi (BB), and bronchiolar (bb) region) is found small and almost constant. For 1 μm diameter aerosols, the percentage deposition is found 0.82%, for 5 μm diameter aerosols, the deposition is predicted 2.56% and at 10 μm the deposition is predicted about 1.93% in bronchi (BB) region. In the bronchiolar region (bb) for 1 μm aerosols, the deposition predicted is 1.5% and at 10 μm about 0.88% is predicted. The deposition of small size attached fraction of radon aerosols is found maximum in the alveolar region as compared to other regions of the respiratory tract and the deposition becomes almost negligible for large size aerosols in this region.

Establishment of Diagnostic Reference Levels in Cone Beam Computed Tomography Scans in the United Arab Emirates

This study aimed to address the knowledge gap in assessing the radiation doses from cone beam computed tomography (CBCT) procedures, establishing a typical value, and estimating effective and organ doses. A total of 340 patients aged 18-80 years were included in this study. Organ doses were estimated using VirtualDose IR software. The typical values were based on median values estimated as 1000 mGy cm2. The mean ED (µSv) per procedure was 149.5 ± 56, and the mean of the peak skin dose during the CBCT examination was 39.29 mGy. The highest organ dose was received by the salivary glands (2.71 mGy), the extrathoracic region (1.64 mGy), thyroid (1.24 mGy) and eyes (0.61 mGy). The patients' doses were higher than in previous studies. Staff awareness, education, training and dose optimisation are highly recommended. With the establishment of local DRLs, patient dosages can be reduced successfully without compromising image quality.

LUNG DEPOSITION RATE AND AEROSOL CHARACTERISTICS OF A NANO AEROSOL NOZZLE WITH DEXAMETHASONE SOLUTION

A nanoaerosol nozzle was designed and the generated aerosol consisting of a diluted dexamethasone solution was measured with Scanning Mobility Particle Sizer (SMPS). The obtained aerosol concentration was fed into the IDEAL lung deposition model for to calculate expected deposition in a human lung. Measurements and calculation clearly show that a substantial fraction reaches the alveolar section of the lungs. Given the generated particle inventory in the nano-size range, the tested nozzle appears to have specic advantages for deposition in deeper pulmonary region over existing “out of the shelf” devices. Considering therapeutic applications, the high share of nano-sized particles make it possible to reduce dosage without compromising the therapeutic effects. While most devices currently in use achieve only about 10 % lung deposition efciency, with the bulk of the aerosolized fraction trapped in the extra-thoracic region. With this novel aerosolizer it is possible to reduce oropharyngeal deposition to about 4,78-5.97 %, leaving 25.6-25.5 % being deposited in the deeper lung, while the remaining fraction being expelled with the exhalation bolus.

Assessment of personal deposited dose of bioaerosols and particles in a wastewater treatment plant facility

The daily deposited dose of bioaerosols and particle mass or number in the human respiratory tract using an exposure dose model (ExDoM2) was quantified in the present study. The dose was calculated for the extrathoracic (ET), tracheobronchial (TB), and alveolar-interstitial (AI) regions of the human respiratory tract. The calculations were performed for viable, cultivable airborne heterotrophic bacteria, mesophilic fast-growing fungi, and total coliforms at a municipal wastewater treatment plant (WWTP) located at a suburban area at a Mediterranean site. The human dose was determined using data from two locations at the WWTP which correspond to two different wastewater treatment stages (aerated grit chamber (indoor) and primary settling tanks (outdoor)) and one outdoor location at the urban background site. In addition, the model simulations were performed for two exposure periods (March to April and May to June 2008). Higher daily deposited dose in the total human respiratory tract was observed for heterotrophic bacteria at the aerated grit chamber, whereas lower values of heterotrophic bacteria were observed at the primary settling tanks. These findings were associated with the corresponding stage of wastewater treatment activities and may be valuable information for determining future dose–response relationships. In addition, higher daily deposited dose was determined in the ET region for the three categories of bioaerosols. Regarding PM10 and PN1, the higher daily deposited dose received by a worker at the aerated grit chamber. Finally, the hazard quotients were estimated and the results showed that the non-carcinogenic effects can be ignored for bioaerosols and PM10 except for workers present at aerated grit chamber. Regarding PM2.5, the non-carcinogenic effects are of concern and cannot be ignored for all cases.

Simulating the effect of individual upper airway anatomical features on drug deposition

This study aims to systematically isolate different anatomical features of the human pharynx with the goal to investigate their independent influence on airflow dynamics and particle deposition characteristics in a geometrically realistic human airway. Specifically, the effects of the uvula, epiglottis and soft palate on drug particle deposition are studied systematically, by carefully removing each of these anatomical features from reconstructed models based on MRI data and comparing them to a benchmark realistic airway model. Computational Fluid Dynamics using established turbulence models is employed to simulate the transport of mono-dispersed particles (3 µm) in the airway at two flow-rates. The simulations suggest three findings: 1) widening the space between the oral cavity and oropharynx and where the soft palate is situated leads to the most dramatic reduction in drug deposition in the upper airway; 2) exclusion of the uvula and epiglottis: a) affects flow dynamics in the airway; b) alters regional deposition behaviour; c) does not significantly affect the total number of particles deposited in the pharynx; and 3) the space adjacent to the soft palate is a key determinant for aerosol deposition in the extrathoracic region and is related to mechanisms of flow acceleration, diversion and recirculation.

Characteristics of inhalable bioaerosols on foggy and hazy days and their deposition in the human respiratory tract

Atmospheric bioaerosols contain live and dead biological components that can enter the human respiratory tract (HRT) and affect human health. Here, the total microorganisms in a coastal megacity, Qingdao, were characterized on the basis of long-term observations from October 2013 to January 2021. Particular attention was given to the size dependence of inhalable bioaerosols in concentration and respiratory deposition in different populations on foggy and hazy days. Bioaerosol samples stained with 4,6-diamidino-2-phenylindole (DAPI) were selected to measure the total airborne microbe (TAM) concentrations with an epifluorescence microscope, while a multiple-path particle dosimetry model was employed to calculate respiratory deposition. The mean TAM concentrations in the particle size range of 0.65–1.1 μm (TAM0.65–1.1) were 1.23, 2.02, 1.60 and 2.33 times those on sunny reference days relative to the corresponding values on days with slight, mild, moderate and severe levels of haze, respectively. The mean concentration of TAMs in the particle size range of 0.65–2.1 μm (TAM0.65–2.1) on severely hazy days was (2.02 ± 3.28) × 105 cells/m3, with a reduction of 4.16% relative to that on the reference days. The mean TAM0.65–2.1 concentration changed from (1.50 ± 1.37) × 105 cells/m3 to (1.76 ± 1.36) × 105 cells/m3, with TAM0.65–1.1 increasing from (7.91 ± 7.97) × 104 cells/m3 to (1.76 ± 1.33) × 105 cells/m3 on days with light fog days and medium fog, respectively. The modeling results showed that the majority of TAM0.65–2.1 deposition occurred in the extrathoracic (ET) region, followed by the alveolar (AL) region. When different populations were examined separately, the deposition doses (DDs) in adult females and in children ranked at the minimum value (6.19 × 103 cells/h) and maximum value (1.08 × 104 cells/h), respectively. However, the inhalation risks on polluted days, such as hazy, foggy and mixed hazy–foggy (HF) days, were still below the threshold for adverse impacts on human health.