Dose Inhaler Research Articles

A Study of the Relationship Among Radon, Thoron and Radioactive Aerosol Particle Distribution in PM2.5 Risk Areas in Kanchanaburi Province, Thailand

Tha Maka is the district with the highest incidence of cancer patients in Kanchanaburi province and is classified as a high-risk area for PM2.5 exposure due to the presence of many sugar factories. Most of the population is in agricultural occupation, leading to the annual burning of sugarcane and rice stubble to start new plantings, which is another cause of air pollution. This study aimed to investigate the correlation among radon, thoron, and airborne particles potentially implicated in lung cancer etiology, which focused on monitoring the concentrations of radon, thoron, and their progeny, as well as analyzing the distribution of particle sizes categorized into 10, 2.5, 1, 0.5, and less than 0.5 μm to assess possible health impacts or lung cancer risk factors. The findings indicated that indoor radon concentrations ranged from 13 to 81 Bq m−3, with a mean of 26.1 ± 11.9 Bq m−3, while indoor thoron concentrations varied from 2 to 52 Bq m−3, averaging 15.7 ± 10.8 Bq m−3. These levels are below the radiation dose limit recommended by the World Health Organization and the International Commission on Radiological Protection (ICRP). The total annual inhalation dose ranged from 0.44 to 2.02 mSv y−1, which is within the usual limits. The average annual effective doses from attached progeny were 0.83 mSv y−1 for radon and 0.57 mSv y−1 for thoron, both of which are regarded to be low. Consequently, based on all the findings, it may be assumed that radon, thoron, and their progeny may not be the primary contributors to lung cancer in the region. Nonetheless, while the mean value falls below the recommended thresholds established by the ICRP or WHO, it is indisputable that in certain regions, representing roughly 6.6% of the total area, the value surpasses the global average documented by the UNSCEAR. Furthermore, the aerosol particle size predominantly observed was less than 1 μm for radon and 0.5 μm for thoron, which is a significant factor that may influence the incidence of respiratory disorders. Nevertheless, as this study was conducted during the non-burning period, future research must be conducted during the burning season, using supplementary factors to acquire more thorough data.

In-vehicle air quality in public buses during real-world trips in Kathmandu Valley, Nepal

Urban air quality shows notable variability across various microenvironments. Transport-related microenvironments often have one of the highest air pollution levels, where commuters have significant exposure to air pollutants. In Kathmandu Valley (KV), Nepal, passengers’ exposure to air pollutants in such microenvironments remain a poorly understood issue. In this study, we analyzed cabin air quality and ventilation rates in public buses operated in KV. In-cabin and in-route ambient air pollution levels were monitored during real-world bus operations in 32 trips on a test route selected in the core city area. A CO2 mass balance model was applied to estimate cabin ventilation rates. The mean in-cabin and outdoor PM2.5 concentrations were 95.9 ± 40.4 (mean ± standard deviation) and 94.7 ± 32.4 μg/m3, respectively. Likewise, mean in-cabin and outdoor PM1 concentrations were 72.5 ± 31.3 and 69.7 ± 25.3 μg/m3, respectively, with mean PM1 to PM2.5 ratio >0.75, indicating that a majority of particle mass was in the sub-micron size range, which is often more health-hazardous. We estimated passengers’ inhalation dose for PM2.5 and PM1 as 5.65 ± 2.32 and 4.27 ± 1.79 μg/km, respectively. Among various factors considered, traffic hour significantly affected both in-cabin and ambient particulate matter concentrations. The trip-average in-cabin CO2 concentration ranged from 513 to 1230 ppm, whereas cabin ventilation rates ranged from 8.0 to 72.4 L/s/person. Ventilation levels in a majority of bus trips were inadequate, especially considering the recommended thresholds to reduce the transmission risk of airborne diseases. Setting standards for ventilation and air conditioning systems in public buses is crucial to ensure thermal comfort, protect bus commuters from the harmful impacts of air pollution, and to improve public transport services in KV.

Mapping the exposure to outdoor radon in the German population

IntroductionData on outdoor radon are generally scarce compared to indoor radon. However, knowledge of the spatial distribution of outdoor radon is necessary to estimate the overall exposure of the population to radon, it supports the prediction of indoor radon and characterizes the natural radon background. Germany has a comprehensive dataset on long-term outdoor radon concentration and the equilibrium factor at national level, which allowed to produce what is probably the only spatially continuous outdoor radon map at national level so far. DataIn this study, outdoor radon concentration measurement data (n = 172) and equilibrium factors (n = 25) from a national survey from 2003 to 2006 were reanalyzed using state-of-the-art machine learning routines. Spatially comprehensive maps of distance to the sea, radon concentration in soil, sand content in topsoil and a terrain-based wind exposure index are used as predictors. MethodsQuantile regression forest was used to map the conditional distribution of outdoor radon concentration at 500 m grid resolution. The equilibrium factor was mapped using a linear regression model. Both maps were combined to derive the equivalent outdoor radon equilibrium concentration. Population weighting of the results was achieved by explicitly accounting for the population distribution using a probabilistic sampling procedure from the estimated conditional distributions. ResultsThe arithmetic mean and the interquartile range (25th to 75th percentile) for the population-weighted outdoor radon concentration for Germany are 9.3 Bq/m³ and 5.8 Bq/m³ to 11.2 Bq/m³, respectively. The mean equilibrium factor is 0.49. The arithmetic mean and the interquartile range (25th to 75th percentile) for the population-weighted outdoor radon equilibrium equivalent concentration are 4.7 Bq/m³ and 2.7 Bq/m³ to 5.9 Bq/m³ respectively. The estimated inhalation dose due to outdoor exposure to radon is 0.056 mSv/a (arithmetic mean), with less than 10 % of the population exceeding a value of 0.1 mSv/a. The unavoidable inhalation dose due to radon exposure (outdoors plus indoors) in Germany is estimated at an arithmetic mean of 0.37 mSv/a. The spatial distribution of radon outdoors is mainly determined by the distance to the sea. The predictors radon concentration in soil, sand in topsoil and wind exposure still have a significant influence, especially at local to regional level. ConclusionKnowledge about the spatial distribution of outdoor radon and its local variability for Germany was improved using a modern regression technique and relevant predictive information. The results confirm a low outdoor radon concentration with a small contribution to the effective dose received by the population from outdoor radon exposure.

Radon quantification in water and dose estimation via inhalation and ingestion across age groups in the Pattan region of North Kashmir, India.

Human survival hinges on access to water, which provides vital necessities. It is crucial to secure reliable, affordable, and uncontaminated water to maintain health and sustain life. For the potential impact of radioactive water pollution on human well-being, a scintillation-based smart RnDuo detector was employed in the Pattan region of North Kashmir Baramulla to quantify radon levels in diverse underground water. The dose contribution to various organs through inhalation and ingestion pathways has been analyzed. The study assesses the levels of radon in water, which varied from 19.88 to 74.37Bq/L with an average of 37.65Bq/L. All of the values were higher than the United States Environmental Protection Agency(USEPA) suggested guideline of 11Bq/L but lower than the 100Bq/L prescribed by the World Health Organization (WHO). The age group-wise inhalation and ingestion doses are higher than the 100 μSv/y recommended by WHO but within the prescribed range of 3-10mSv/y as suggested by the International Commission on Radiological Protection (ICRP). Doses to various organs (lungs and stomach) are also calculated in the present study. The results of the present investigation will help to enhance the quality of the water and guide future epidemiological studies.

Firefighters’ occupational exposure to air pollution: impact on COPD and asthma—study protocol

IntroductionFirefighting continues to be among the most hazardous yet least studied occupations in terms of the impact of exposure to occupational disease. In particular, firefighters are at increased risk of...

Microplastics in Urban Ambient Air: A Rapid Review of Active Sampling and Analytical Methods for Human Risk Assessment

This study conducted a rapid review to evaluate active air sampling and analytical methods for characterizing outdoor air microplastics in urban areas. We synthesized information from 35 peer-reviewed journal articles. Studies utilizing active sampling methods were able to provide detailed data on inhalation concentrations and doses. The analytical techniques reviewed were categorized into microscopy, Fourier Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), and mass spectrometry, including pyrolysis–gas chromatography (Py-GC). While conventional FTIR and Raman spectroscopy can identify microplastics in total suspended particles, advanced instruments such as µRaman and SEM are crucial for analyzing inhalable microplastics (e.g., particles smaller than 10 µm). Characterizing the shapes and colours of microplastics can provide qualitative estimates of their sources, with fibres and the colour black being the most predominant characteristics. Establishing dose–response relationships for health effects requires quantitative analyses; thus, combining techniques like µRaman with Py-GC is essential for comprehensive human risk assessments. Future studies should focus on identifying and quantifying inhalable microplastic compounds that are relevant to human health.

Environmental impact of inhaled medicines: A Thoracic Society of Australia and New Zealand position statement.

Globally, more than 1.2 billion inhalers are purchased for asthma and chronic obstructive pulmonary disease (COPD) annually. In Australia and New Zealand, pressurized metered dose inhalers (pMDIs) are the leading delivery device prescribed and pMDI salbutamol can be purchased over the counter in Australia. These inhalers are a major contributor to healthcare related greenhouse gases. This is due to the propellants that they currently contain which have extremely high global warming potential (GWP). In this position paper, we report the findings of a Thoracic Society of Australia and New Zealand (TSANZ) working group on the environmental impact of inhaled respiratory medicines. We reviewed the use of inhaled medicines in Australia and New Zealand and their contribution to climate change and other environmental degradation. We propose strategies for health professionals and consumers to reduce environmental impact in the management of airway diseases. These include accurate diagnosis to avoid unnecessary treatment, better disease control to minimize the need for reliever therapy and actively choosing inhaler devices with lower environmental impacts when clinically appropriate. Inhaler selection should be tailored to the individual, aiming to achieve the best possible clinical outcome. Choosing an appropriate inhaler for an individual involves consideration of factors such as dexterity, inspiratory capacity and cost. In our current climate emergency and with the availability of lower carbon alternatives, health professionals should also consider environmental impact.

Spatio-temporal analysis of bicyclists' PM2.5 exposure levels in a medium sized urban agglomeration.

Many cities have promoted decarbonized transportation modes to mitigate climate change, reduce air pollution and promote healthy behaviors. However, cyclists may be particularly exposed to higher concentrations of on-road air pollutants than other commuters due to their proximity to traffic, higher breathing rates, and prolonged commutes. In addition, there is scarce information analyzing the geographic exposure levels of cyclists in medium-sized urban agglomerations of Latin American cities. We aimed to assess cyclists' exposure to PM2.5 at the spatio-temporal level using low-cost sensors in the Mendoza Metropolitan Area, Argentina. We calculated PM2.5 inhalation doses (IDs) for different routes with distinctive characteristics, considering different age ranges and gender of cyclists. The dose was represented as temporally and spatially disaggregated exposure maps, one of the first to represent it in Latin America using this method. All link types analyzed exhibited significant differences in PM2.5 concentrations, although the most frequent concentrations were less than 5µgm-3, with secondary peaks of 6.5 and 9µgm-3. As expected, ID increases with age and is greater in males than in females. Our findings further reinforce the fact that route choice (busy vs. quiet) and time of day (peak vs. off-peak) appreciably affect the pollutant exposure of cyclists. All these results could be helpful in the selection of alternative cycling routes with lower PM2.5 at different hours of day but also enable us to investigate further implications of exposure to PM2.5 for the health of urban bicycle commuters.

Radiation dose estimation for indoor radon, thoron and their progenies using a stochastic method-a small-scale survey in Wuhan, China.

Passive radon monitors with CR-39s are widely used in major epidemiological surveys. However, the conventional CR-39 track density determining strategy makes it difficult to accurately estimate the concentration because of the heterogeneity of tracks on CR-39s. This study introduced a stochastic method, Latin hypercube sampling, to improve the track density determining strategy and provide the probability distribution of 222Rn concentration and equilibrium equivalent thoron concentration. The first 222Rn and 220Rn discriminated survey was conducted in Wuhan, China, in 2018 using RADUET® and deposition-based passive 220Rn progeny monitors and applying the stochastic method to the measurement. The results indicate that the stochastic method could decrease the effects of the track heterogeneity on the CR-39s and provide reliable results. The 220Rn progeny contributed more than 40% of the total inhalation dose in the survey, which cannot be ignored in urban family dwellings.

Flow Profiles Identify Sources of Poor Metered Dose Inhaler Technique: An Observational Study in Long-Term pMDI Users

BackgroundInhaled medications are commonly used as therapy for obstructive lung disease (OLD) yet poor technique from pressurized metered dose inhalers (pMDI) can severely limit drug delivery and therapeutic efficacy. A novel flow sensor has been developed to characterize inhalation flow profiles from pMDIs. Research QuestionAmong OLD subjects, flow profiles during pMDI inhalation maneuvers would expose poor patterns of pMDI use, which can be used to remediate pMDI technique. Study Design and MethodsA novel flow sensor was coupled to a placebo pMDI inhaler to characterize inhalation technique in 70 OLD participants from a pulmonary clinic. pMDI inhalation flow profiles generated actuation timing, mean inspiratory airflow (MIF) and inspired volume before and after visualizing these features. McNemar’s was used to characterize the impact of training on pMDI inhalation metrics. The post-actuation inspired volume was normalized to inspiratory capacity (IC). ResultsAmong participants with 17.4 (SD = 17.9) years of pMDI use, flow profiles uncovered mistimed actuations in 47.1% and poor inspiratory flow rates in 30.0% of subjects. After visualizing flow profiles, participants improved actuation timing (c2(1) =12.042, p < .001), mean inhaled volume (87.9 to 105.6% of IC, p<0.001) and the combined inhalation metrics (c2(1) =8.45, p = 0.003). InterpretationFlow profiles helped uncover and remediate specific defects in pMDI technique in the majority of chronic OLD users. Flow profiles from inhaled medications can be used to enhance drug delivery to the lung.

Direct measurement of indoor thoron and radon progeny and estimation of inhalation dose in three cities in Gabon: Comparison of the use of thoron typical and measured equilibrium factor values

This study focuses on public exposure to natural radioactivity caused by the inhalation of radon and thoron progeny in homes in Franceville, Moanda and Mounana in Gabon. The equilibrium factor (FTn) between thoron and its progeny was determined experimentally for a proper estimate of the effective dose. In order to assess internal exposure due to radon and thoron progeny, 150 passive radon-thoron discriminative detectors (RADUET) and thoron progeny monitors were deployed for about 3 months in the above-mentioned towns. The results of the measurements obtained showed that the average concentrations of thoron progeny (EETC) were 1.54 ± 0.08 Bq m−3, 3.05 ± 0.09 Bq m−3 and 1.84 ± 0.11 Bq m−3 in Franceville, Moanda and Mounana, respectively. The ranges of the measured thoron equilibrium factors were 0.004–0.710, 0.005–0.750, and 0.006–0.794 in Franceville, Moanda and Mounana, respectively. The arithmetic and geometric mean values were, respectively, 0.183 and 0.117 in Franceville, 0.184 and 0.122 in Moanda, and 0.221 and 0.140 in Mounana. The experimentally determined equilibrium factor (FTnexp) allowed us to compare the value of the experimentally determined effective dose with the theoretically determined one calculated using the equilibrium factor proposed by United Nation Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) 2000 report. FTnexp values were around 6–11 times greater than the UNSCEAR typical value. The ranges, arithmetic and geometric mean EERC values determined were 30.40–55.60 Bq m−3, 24.00 ± 0.90 Bq m−3 and 41.68 (1.00) in Franceville, 36.40–62.50 Bq m−3, 45.30 ± 0.70 Bq m−3 and 44.72 (1.00) in Moanda, and 35.00–90.00 Bq m−3, 50.00 ± 2.00 Bq m−3 and 48.50 (1.00) in Mounana. The mean values of the annual effective inhalation dose due to thoron progeny determined using FTnexp were 0.32 mSv (compared to 0.049 mSv), 0.63 mSv (compared to 0.103 mSv), and 0.39 mSv (compared to 0.055 mSv) in Franceville, Moanda and Mounana, respectively. The main conclusion of this study is that indirect estimations of thoron progeny concentrations considerably underestimate the estimation of the annual effective inhalation dose.

Molecular imaging of excitability difference between alkaloids/salts (nicotine, nicotinic benzoate, caffeine and arecoline hydrobromide)

Comparison of the excitability of four different alkaloids/salts, including nicotine, nicotinic benzoate, caffeine and arecoline hydrobromide. Based on positron emission tomography (PET) imaging and 18F-Fallypride, a novel technique for measuring alkaloid/salt excitability in SD rats was developed. Different doses and types of alkaloids/salts were administered to the SD rats in a single nebulised inhalation.The results showed that: (1) PET imaging technology can detect the excitability intensity of SD rats after single inhalation of alkaloids/salts in non-invasive real time and the optimal PET scanning time of four different alkaloids/salts (nicotine, nicotinic benzoate, caffeine and arecoline hydrobromide) were slightly different. (2) The excitatory saturation effect of four alkaloids/salts was observed in SD rats after single inhalation and the saturation effect doses of nicotine, nicotine benzoate, caffeine and arecine hydrobromide were 0.063 mg/kg, 0.075 mg/kg, 0.33 mg/kg and 0.075 mg/kg, respectively. (3) In the case of single inhalation of the same dose of four alkaloids/salts, male SD rats inhaled arecoline hydrobromide with the strongest excitability, while female SD rats inhaled nicotinic benzoate. A PET method for noninvasive real-time detection of alkaloid/salt excitability in SD rats was established.The finding of an excitatory saturation effect for four alkaloids/salts (nicotine, nicotinic benzoate, caffeine and arecoline hydrobromide) and the presence of excitatory intensity and gender differences at the same dose of inhalation of four alkaloids/salts, which provide a new theoretical basis for determiningthe content of alkaloids/salts.

Evaluation of asthma control after reinforcement of proper inhaler techniques in a tertiary care center in northern India.

Asthma is an obstructive lung disease with high prevalence. Symptom control in asthma remains poor despite significant advancements in treatment guidelines and inhalational devices. This is often attributed to inadequate patient adherence to the inhaler technique and insufficient education on its long-term use. Through this study, we aimed to assess the impact of reinforcement of proper inhaler technique on asthma symptom control and quality of life. A prospective cohort of 400 asthma patients using dry powder inhalers and metered dose inhalers was recruited in the outpatient clinic of our hospital. At the time of recruitment, the correctness of inhaler technique usage was assessed, and the pre-test Inhaler Technique Score (ITS) was recorded for each patient. Then, a ten-step inhalation technique was taught through demonstration, and the post-test ITS score was recorded again. This was done for each patient at monthly intervals for 3 months. Along with it, two tailored questionnaires, the Asthma Control Test (ACT) and Asthma Quality of Life Questionnaire (AQLQ), were administered at each visit to assess disease control and quality of life. Significant enhancements in inhalation technique were noted from the first to the third visit using the ten-step inhalation usage scores, which improved from 6.91 to 9.87 (out of 10) (p<0.001), paralleled by ACT score increases from 17.06 to 19.37 (out of 25) (p<0.001) from visits one to two, and from 19.37 to 20.52 (out of 25) (p<0.001) from visits two to three, signifying improvement in symptom control. Quality of life similarly improved from 4.45 to 5.12 to 5.45 (out of 7) (p<0.001) across the three visits as assessed by AQLQ. In conclusion, promoting proper inhaler technique through structured education programs is crucial for optimizing long-term asthma management and enhancing patients' quality of life.

Features, reasons, and significance of radon and thoron attributable radiological dose in the indoor environment

Humans receive around 50% of natural radiation dose due to 222Rn (radon), 220Rn (thoron) and their decay products. Several field campaigns measuring these gases and the decay products in different regions of India have been conducted in the recent past. Some of these studies measured indoor activity concentration and/or dose due to these gases and the associated decay products. This work compares the fraction of 222Rn and decay products and 220Rn and decay products in inhalation dose for 10 studies conducted in Uttarakhand state. It is seen that AEDT (annual effective dose due to 220Rn and decay products) for these regions varies between 21 and 48% and it is significantly higher than the averaged worldwide reference value of 6%. Based on elaborative measurements performed in the Bageshwar district (present work), Almora and Nainital districts (our previous campaigns); the reasons for this high value have been explored. It was observed that a higher source term for mud houses could be the main reason for the high AEDT range. Interestingly, preliminary analysis revealed that the fraction is higher for the dwellings situated at higher altitudes thus indicating the role of the unavailability of modern building construction materials at remote locations. The study highlights the significant contribution of thoron in the Indian Himalayas.

Machine learning-enhanced stochastic uncertainty and sensitivity analysis of the ICRP human respiratory tract model for an inhaled radionuclide

The International Commission on Radiological Protection (ICRP) has developed the reference Human Respiratory Tract Model (HRTM), detailed in ICRP Publications 66 and 130, to estimate the deposition and clearance of inhaled radionuclides. These models utilize reference anatomical and physiological parameters for particle deposition (PD). Biokinetic models further estimate retention and excretion of internalized particulates, aiding the derivation of inhalation dose coefficients (DC). This study aimed to assess variability in deterministic131I biokinetic and dosimetry models through stochastic analysis using the updated HRTM from ICRP Publication 130. The complexities of the ICRP PD model were reconstructed into a new, independent computational model. Comparison with reference data for total PD fractions for reference worker, solely a nose breather, covering activity median aerodynamic diameters from 0.3μm to 20μm, showed a 1.04% relative and 0.7% absolute difference, demonstrating good agreement with ICRP deposition fractions. The deterministic DC module was reconstructed in Python and expanded for stochastic analysis, systematically expanding deposition components from HRTM and assigning probability distribution functions to uncertain parameters. These were integrated into an in-house stochastic radiological exposure dose calculator, utilizing latin hypercube sampling. A case of an occupational radionuclide intake was explored, in which biodistribution and committed effective DC (CEDC) were computed for131I type F, considering a lognormal particle size distribution with a median of 5μm. Results showed the published ICRP reference CEDC marginally exceeds the 75th percentile of observed samples, with log-gamma distribution as the best-fit probability distribution. A Random Forest regression model with SHapley Additive exPlanations was employed for sensitivity analysis to predict feature importance. The analysis identified the HRTM particle transport rates scaling factor, followed by the aerodynamic deposition efficiency in the alveolar interstitial region as the most impactful parameters. This study offers a unique stochastic approach on inhaled particulate metabolism, enhancing radiation consequence management, medical countermeasures, and dose reconstruction for epidemiological studies.

Environmental impact of pressurised metered dose inhalers versus dry powder and soft mist inhalers at a tertiary Melbourne hospital.

The carbon footprint of devices to deliver inhaled respiratory medications has come into focus as climate change has been identified as a worldwide emergency. Metered dose inhalers (MDIs) contain hydrofluorocarbons that have significant global warming potential compared to dry powder inhalers (DPIs) and soft mist inhalers (SMIs), which do not use a propellant gas. A 12-month pharmacy inpatient dispensing audit demonstrated that inpatient MDI use significantly outweighed that of DPIs and SMIs and accounted for approximately 99% of inhaler-related greenhouse gas emissions at our hospital.

Oral Manifestations in Asthmatic Patients Using Metered Dose Inhaler and Dry Powder Inhaler

Background: The prevalence of asthma indicates the importance of studying oral manifestations of inhalers as one of the indications of asthma. This study compares two methods of using inhalers, Metered Dose Inhaler (MDI) and Dry Powder Inhaler (DPI) in asthmatic patients. Methods: 100 asthmatic patients (50 MDI-treated, 50 DPI-treated) and 50 healthy individuals were selected by convincing sampling. The three sampled groups were gender- and age-matched. We performed a clinical examination, recorded the information, and analyzed the data by SPSS21 software using a t-test and one-way ANOVA for quantitative and Pearson’s chi-square test for qualitative indicators. Results: DMFT index (p-value 0.001), fissured tongue (p-value 0.005), xerostomia (p-value 0.001), and dental erosion (p-value: 0.011) in MDI-treated patients were significantly higher than the other two groups, while the geographic tongue (p-value 0.008) was significantly higher in DPI-treated patients than in the other two groups. It showed that periodontal disease and median rhomboid glossitis had no significant difference between the three groups. Conclusion: Due to the higher incidence of manifestations in MDI, it is expected that physicians give more attention to prescribing inhalers and give them the necessary training to maintain oral and dental hygiene.

Comparative analysis of particle exposure in commuters: Evaluating different modes of transportation in Tehran

Daily commuting significantly contributes to the overall exposure to particulate matter (PM) in urban areas, underscoring the need to understand the factors influencing PM exposure. This study assessed personal exposure levels and inhalation doses of PM2.5, and PM10 across various transportation modes in Tehran, Iran. The study included buses, open-window taxis, subways, walking, and cycling for over 125 trips. Data were collected during the morning and evening peak hours using low-cost sensors, with an average trip distance of 7.50 km. On average, buses exhibited the highest mean PM2.5 concentration (25.0 μgm3), followed by subways (17.0 μgm3), taxis (14.4 μgm3), cycling (13.5 μgm3), and walking (8.80 μgm3). Pearson correlation analysis showed a strong relationship between traffic volume and PM concentrations in taxi and bus modes (r = 0.78 and 0.56, respectively). Subway commuters experienced the lowest PM2.5 inhalation dose (2.50 μg), whereas bus commuters experienced the highest (6.20 μg). Pedestrians had the highest average inhalation dose of PM2.5 with 20.7 μg due to longer trip durations. The daily average PM2.5 levels in all transportation modes exceeded the WHO thresholds by 1.60 times. These findings offer crucial insights into personal exposure concentrations among commuters and serve as a basis for effective air quality management plans and broader global investigations of air pollution.

Radionuclides distribution in soils and radon level assessment in dwellings of Mungo and Nkam Divisions, Cameroon.

Radionuclide and radon levels have been investigated in soil samples and residential environments within the Mungo and Nkam Divisions of the Littoral Region. These analyses employed gamma spectrometry facilitated by a NaI (Tl) detector for soil samples, yielding average activity concentrations of 226Ra, 232Th, and 40K at 23.8, 72, and 105Bqkg-1, respectively. Various radiological parameters were calculated to evaluate radiological hazards. Additionally, the indoor radon concentrations were quantified utilizing the CR-39 solid-state nuclear track detector (Radtrack), revealing an average concentration of 25Bqm-3 and an associated inhalation dose of 0.66mSv y-1. Risk assessments for lung cancer attributable to indoor radon exposure incorporated models such as the Harley model. An observed moderate correlation between indoor radon levels and external 226Ra concentrations implies that radon intrusion indoors might be substantially influenced by the 226Ra present in the subjacent soil, considering the construction of residential structures directly upon these terrains.

Inhaled corticosteroid delivery is markedly affected by breathing pattern and valved holding chamber model.

There is a scarcity of high-quality research on the efficient delivery of inhaled corticosteroids using valved holding chambers (VHCs) in children. The delivered dose (DD) of fluticasone from a metered dose inhaler (pMDI) was tested using four VHCs: AeroChamber plus Flow-Vu (AC), Babyhaler (BH), EasyChamber (EC), and Optichamber Diamond (OD). The in vitro setup included an anatomical child throat model, Next Generation Impactor, and a breathing simulator to generate tidal breathing of a four and a 6-year-old child, and adult type single inhalation. OD showed the lowest proportion of fluticasone trapped in the throat with all breathing patterns. AC showed similar fine particle dose (FPD) in the respirable range (1-5 µm) irrespective of the breathing pattern. For BH, the median FPD 1-5 µm was highest during adult breathing. OD and EC showed higher overall DD and higher doses in the 1-5 µm range with paediatric breathing profiles compared to adult inhalation. The median DD and FPD 1-5 µm were significantly lower with BH compared to any other VHCs during tidal breathing. Compared to EC, the FPD of the other VHCs were skewed towards <2 µm particles. Fluticasone delivery is markedly affected by breathing pattern and VHC model. The observed differences in throat deposition and FPD delivered may have significant clinical implications for side effects and controlling airway inflammation. All VHCs intended for paediatric use should undergo testing using internationally recognised standardised methods incorporating clinically relevant paediatric breathing patterns.