Respiratory Deposition Dose Research Articles

Investigating Age-Specific Respiratory Deposition Doses of Traffic-Related Particles at Urban Intersections in Pune, India

Investigating Age-Specific Respiratory Deposition Doses of Traffic-Related Particles at Urban Intersections in Pune, India

Chemically Resolved Respiratory Deposition of Ultrafine Particles Characterized by Number Concentration in the Urban Atmosphere.

Ultrafine particles (UFPs) dominate the atmospheric particles in number concentration, impacting human health and climate change. However, existing studies primarily rely on mass-based approaches, leading to a restricted understanding of the number-based and chemically resolved health effects of atmospheric UFPs. In this study, we utilized a high-mass-resolution single-particle aerosol mass spectrometer to investigate the online chemical composition and number size distribution of ultrafine, fine, and coarse particles during the summertime in urban Shenzhen, China. Human respiratory deposition dose assessments of particles with varying chemical compositions were further conducted by a respiratory deposition model. The results showed that during our observation, particles containing elemental carbon (EC) were the dominant components in UFPs (0.05-0.1 μm). Compared to fine and coarse particles, UFPs can deposit more deeply into the respiratory tract with a daily dose of ∼2.08 ± 0.67 billion particles. Among the deposited UFPs, EC-cluster particles constituted ∼85.7% in number fraction, accounting for a daily number dose of ∼1.78 billion particles, which poses a greater impact on human health. Simultaneously, we found discrepancies in the chemically resolved particle depositions among number-, surface area-, and mass-based approaches, emphasizing the importance of an appropriate metric for particle health-risk evaluation.

Seasonal analysis of particulate matter and its exposure on urban bikers in Nashik city, India

Introduction: Exposure to Particulate Matter (PM) can cause ill health effects such as coughing, allergies, decreased lung function, chest discomfort and pain. The current study aims to monitor particulate matter concentrations on the highways in Nashik, India and to estimate its exposure to the bikers in the form of Respiratory Deposition Doses (RDDs) with its seasonal variation.
 Materials and methods: Low-cost air quality monitor was mounted on the bike to measure Particulate Matter (PM1, PM2.5 and PM10) concentrations at breathing level. Extensive mobile monitoring was performed on seven highway stretches passing through city limits at morning and evening peak hours for all the weekdays for three seasons.
 Results: The PM concentrations differed on each route seasonally as well as at peak hours in morning and evening. The maximum PM1, PM 2.5 and PM10 concentrations monitored were 119.84 μg/m3, 218.85 μg/m3 and 239.25 μg/m3 respectively on Route R3 in Winter morning. The maximum RDDHD exposure on R5 and R3 in Winter mornings was due to PM10. While maximum RDDTB and RDDAL exposure on R5 in Winter morning and evening was due to PM2.5. Also, the seasonal and particle size effect on RDD has been studied which exhibits higher rise in exposure in Winter mornings due to PM2.5.
 Conclusion: This study reveals that maximum exposure was observed during Winter mornings. The results recommend that seasons have a substantial effect on PM concentrations and their exposure. The minimum exposure was observed in monsoon, followed by summer and the maximum exposure was seen in winters.
 

Particle Number Size Distribution in Three Different Microenvironments of London

We estimated the particle number distributions (PNDs), particle number concentrations (PNCs), physicochemical characteristics, meteorological effects, and respiratory deposition doses (RDD) in the human respiratory tract for three different particle modes: nucleation (N6–30), accumulation (N30–300), and coarse (N300–10,000) modes. This study was conducted in three different microenvironments (MEs) in London (indoor, IN; traffic intersection, TI; park, PK) measuring particles in the range of 6 nm–10,000 nm using an electrical low-pressure impactor (ELPI+). Mean PNCs were 1.68 ± 1.03 × 104 #cm−3, 7.00 ± 18.96 × 104 #cm−3, and 0.76 ± 0.95 × 104 #cm−3 at IN, TI, and PK, respectively. The PNDs were high for nucleation-mode particles at the TI site, especially during peak traffic hours. Wind speeds ranging from 0 to 6 ms−1 exhibit higher PNCs for nucleation- and accumulation-mode particles at TI and PK sites. Physicochemical characterisation shows trace metals, including Fe, O, and inorganic elements, that were embedded in a matrix of organic material in some samples. Alveolar RDD was higher for the nucleation and accumulation modes than the coarse-mode particles. The chemical signatures from the physicochemical characterisation indicate the varied sources at different MEs. These findings enhance our understanding of the different particle profiles at each ME and should help devise ways of reducing personal exposure at each ME.

Spatial variability and health assessment of particle number concentration at different exposure locations near urban traffic arterial: A case study in Xi'an, China

Urban traffic arteries are considered as hot-spots of pollution of particle number concentration (PNC), but the knowledge of spatial variability and exposure levels of PNC with different particle sizes emitted by vehicles is yet less reported. In this paper, PNC in the size range from 6 to 10,000 nm were measured using the Electrical Low-Pressure Impactor Plus (ELPI+) at four sites near high-density traffic in Xi'an, including one traffic, one roadside, and two urban background. The results showed that PNC was highest at the distance closest to the traffic sources, and decreased exponentially with distance. Vehicle exhaust was the primary source of ambient ultrafine particle (UFP), contributing 60.03% and 54.48% of the number concentration of UFP in the clean and haze weathers, respectively. The average PNCs measured at the traffic site were 2.24 and 3.17 times greater than those at the roadside and urban background sites, respectively. Coarse mode particle concentrations exhibited a higher level at the roadside site due to the secondary dust generated by vehicles. An interesting phenomenon that an inverted U-shaped relationship between measured UFP levels and traffic flows was found when the flow was higher than 6000 veh h−1. Strong spatial inhomogeneity for UFP along the urban road, whereas particles larger than 100 nm in diameter tend to similar concentration distributions. The mean respiratory deposition dose (RDD) at four locations was (7.14 ± 1.12) × 105 particles h−1, with the highest (14.61 ± 2.29) × 1010 particles h−1 at the traffic site. Retired people had a higher exposure of UFP compared to children and adults. This improved understanding of the impact of vehicle emissions on the distribution of PNC near-road.

Size-fractionated ambient particulate matter induce toxicity: Oxidative potential, cytotoxic effect and inflammatory potential

Present study highlighted the importance of examining the toxicological profile of size-segregated particulate matter (PM) bound metals (Fe, Mn, Ni, Pb, Zn, Cu, Cr, Co, Cd) at urban site of Pune city, India. The total aerosol mass was composed of 61.2% and 38% fine and coarse particles, respectively with maximum distribution observed in 4.7–2.1 μm size mode. Elemental size distributions indicated the prime association of Fe, Mn and Zn with coarse sized PM, while remaining metals were predominantly associated with fine PM. Seasonal mass and elemental distribution profile of size-resolved PM was characterized with maximum concentration found in winter season. Enrichment factor analysis revealed the contribution of anthropogenic emissions to Co and Ni in fine mode while less enriched metals, Fe and Mn were allied with crustal and natural sources. Oxidative potential of particles in terms of Dithiothreitol (DTT) loss was found to be maximum in the size range of 4.7–1.1 μm with dominant contribution of PM bound metals (Fe, Cu, Cr, Mn, Ni, Pb, and Zn). On exposure to PM samples, prominent enhancement in the expression of cytokines (especially TNFα) as compared to the control has confirmed their inflammatory nature. Incubation of A549 cells with PM suspension (75 mg/ml) caused pronounced reduction (p < 0.01) in cell viability with significant morphological changes, associated with cell death. Respiratory deposition doses of PM in head region were found to be more impacted by coarse sized particles while contribution of fine PM was dominant in alveolar and tracheobronchial region, signifying serious health risks to the exposed population. In addition to the basic knowledge of toxicity mechanisms associated with size fractionated PM, these results together with the analysis of correlation between PM bound metals and biological assays will be relevant to better characterize the potential health risks and possible future mitigation strategies.

Respiratory deposition dose of PM2.5 and PM10 during night and day periods at an urban environment

Abstract Inhalation of particulate matter (PM) has been extensively associated with the worsening and onset of cardiorespiratory diseases, being responsible for millions of deaths annually. Assessment of PM deposition in the human respiratory tract is critical to better understand the health risks from environmental exposure of vulnerable age groups. In this study, PM2.5 and PM10 day-night monitoring campaigns during the cold season were carried out in Bragança, Portugal. The multiple-path particle dosimetry (MPPD) model was used to quantify total and regional depositions in the human respiratory tract for four different age groups: infant (3 months), child (9 years), adult (21 years) and elderly (65 years). The results showed that concentrations for both PM fractions were higher during the night, a period marked by the burning of biomass for residential heating. Regional deposition fractions (DF) for PM2.5 were in the ranges 17–38% (head), 4–14% (tracheobronchial) and 20–28% (pulmonary), while for PM10 were 24–67% (head), 4–27% (tracheobronchial) and 12–22% (pulmonary). Children and the elderly were found to be the most vulnerable groups to PM deposition, especially for the TB and H regions, respectively. The lifetime cancer and non-cancer risks associated with exposure to PM2.5 exceeded the recommended limits, especially for children &lt;10 years old. These findings provide useful information to alert authorities to the need to take action to reduce the pollution burden and protect the health, in particular of those most susceptible. Graphical Abstract

Fine and nano particles in the school environments and the respiratory deposition doses to schoolchildren in a Middle City of Jambi, Indonesia

Five public high schools in Jambi, Indonesia, located on the roadside, were chosen as sampling sites, i.e., at the school gate (SG) and schoolyard (SY), to assess the respiratory deposition doses (RDDs) to schoolchildren during the COVID-19 pandemic (December 2021 to February 2022). The fine- and nano-particles information was proven to be critical and limited during the pandemic, but school activities have resumed as usual, even though they only occur for ~4 hours per day at that time. The results show average PM concentrations at the school gate (SG) were higher than those at the schoolyard (SY) regardless of the site location, which was attributed to a difference in influences from road traffic that may be due to the distance from the road. Each PM2.5 concentration, particularly at SY during the school day, exceeded the World Health Organization’s PM2.5 daily standard (15 μg m-3), resulting in higher RDDs compared to other particle sizes, particularly for headways. The deposition of PM2.5 and PM0.1 needs more attention since RDDs have higher values and can infiltrate the alveoli more deeply. Overall, these findings will help to improve health surveillance and guide future efforts in Indonesia to develop air pollution mitigation strategies, particularly for children during the school day.

Comparison of PM spatiotemporal variations and exposure at adjacent signalized intersection and roundabout

As urban traffic nodes, signalized intersections and roundabouts gather a large number of vehicles, forming traffic particulate matter (PM) hotspots. However, related studies have focused only on signalized intersections, and knowledge of PM characteristics on roundabouts are still scarce. For this reason, we carried out mobile and fixed-site monitoring of PM mass and number concentrations and comparative analysis, at an adjacent roundabout and intersection. The attenuation curves of PM2.5 concentrations down the departure roads from the roundabout and intersection centers showed an exponential decay, but their distribution profiles were obviously different. Particle number concentration (PNC) first increased and then decreased at the roundabout, while it was similar to PM2.5 with exponential decay at the intersection. The temporal variation of PNC in different particle sizes differed between the roundabout and intersection. A Generalized Additive Model (GAM) quantified the contribution of background concentration, Meteorological conditions, and traffic volume to PM2.5 at the roundabout and the intersection, respectively, identifying their different influential levels. Lastly, using field data of this case study, the average respiratory deposition dose (RDD) rates were estimated for adults and children. The study can help formulate effective urban traffic pollution control strategies.

The presence of polycyclic aromatic hydrocarbons (PAHs) in air particles and estimation of the respiratory deposition flux

Polycyclic aromatic hydrocarbons (PAHs) in the atmospheric particles constitute a topic of growing health concern. This study aims to calculate PAH concentrations, identify the source, assess the health risk from exposure to carcinogenic PAHs, and the respiratory deposition flux. PM10 and PM2.5 were collected in September 2019 in the urban, semi-urban, and semi-urban-industrial areas of Kuala Lumpur, Batu Pahat, and Bukit Rambai, respectively. A total of 18 PAHs from PM10 and 17 PAHs from PM2.5 were extracted using dichloromethane and determined using gas chromatography coupled with a flame ionization detector (GC-FID). The health risk assessment (HRA) calculated included B[a]P equivalent (B[a]Peq), lifetime lung cancer risk (LLCR), incremental lifetime cancer risk (ILCR), and respiratory deposition dose (RDD). The results show PAHs in PM10 recorded in Kuala Lumpur (DBKL), Batu Pahat (UTHM), and Bukit Rambai are 9.91, 8.45, and 9.57 ng/m3, respectively. The average PAHs in PM2.5 at the three sampling sites are 11.65, 9.68, and 9.37 ng/m3, respectively. The major source of PAHs obtained from the DRs indicates pyrogenic activities for both particle sizes. For PM10, the total B[a]Peq in DBKL, UTHM, and Bukit Rambai were 1.97, 1.82, and 2.32 ng/m3, respectively. For PM2.5 samples, the total B[a]Peq in DBKL, UTHM, and Bukit Rambai were 2.80, 2.33, and 2.57 ng/m3, respectively. The LLCR and ILCR show low to moderate risk for all age groups. The RDD of adults and adolescents is highest in both PM10 and PM2.5, followed by children, toddlers, and infants. Overall, we perceive that adults and adolescents living in the urban area of Kuala Lumpur are at the highest risk for respiratory health problems because of prolonged exposure to PAHs in PM10 and PM2.5, followed by children, toddlers, and infants.

Investigation of the Exposure of Schoolchildren to Ultrafine Particles (PM0.1) during the COVID-19 Pandemic in a Medium-Sized City in Indonesia.

The health risk of schoolchildren who were exposed to airborne fine and ultrafine particles (PM0.1) during the COVID-19 pandemic in the Jambi City (a medium-sized city in Sumatra Island), Indonesia was examined. A questionnaire survey was used to collect information on schoolchildren from selected schools and involved information on personal profiles; living conditions; daily activities and health status. Size-segregated ambient particulate matter (PM) in school environments was collected over a period of 24 h on weekdays and the weekend. The personal exposure of PM of eight selected schoolchildren from five schools was evaluated for a 12-h period during the daytime using a personal air sampler for PM0.1 particles. The schoolchildren spent their time mostly indoors (~88%), while the remaining ~12% was spent in traveling and outdoor activities. The average exposure level was 1.5~7.6 times higher than the outdoor level and it was particularly high for the PM0.1 fraction (4.8~7.6 times). Cooking was shown to be a key parameter that explains such a large increase in the exposure level. The PM0.1 had the largest total respiratory deposition doses (RDDs), particularly during light exercise. The high level of PM0.1 exposure by indoor sources potentially associated with health risks was shown to be important.

Pollutant concentrations and exposure variability in four urban microenvironments of London

We compared various pollutant concentrations (PM1, PM2.5, PM10, PNC, BC) at four different urban microenvironments (MEs) in London (Indoor, IN; Traffic Intersection, TI; Park, PK; and Street Canyon, SC). The physico-chemical characteristics of particles were analysed, and the respiratory deposition doses (RDD) were estimated. Field measurements were conducted over a period of 121 days. The mean PM2.5 (PNC) concentrations were found to be 9.47 ± 7.05 (16366 ± 11815), 8.09 ± 4.57 (10951 ± 6445), 5.11 ± 2.96 (7717 ± 4576), 3.88 ± 3.06 (5672 ± 2934) μg m−3 (# cm−3) at TI, SC, PK and IN, respectively. PM2.5, PM10 and PNC exhibited a trend of TI > SC > PK > IN; higher concentrations for PM1 and BC were observed at IN than PK due to the emissions from printers, producing a trend of TI > SC > IN > PK. We observed 12%–30% higher fine PM concentrations at TI and SC sites during morning peak (07:00–09:30) than the evening peak hours (16:00–19:00); while IN showed a smaller variation in fine PM concentrations compared with outdoor TI, PK and SC sites owing to their prevalence in the IN for a longer time. Fine and ultrafine PM containing potentially toxic trace transition metals including Fe, Ti, Cr, Mn, Al and Mg were detected by high resolution electron microscopy at all sites. There was a similar relative abundance of different elements at the TI, IN and PK sites, which suggests a transport of PM between MEs. RDD for PM1 was highest (2.45 ± 2.27 μg h−1) at TI for females during running; PM2.5 and PM10 were highest at SC (11.23 ± 6.34 and 37.17 ± 20.82 μg h−1, respectively). The results show that the RDD variation between MEs does not follow the PM concentration trend. RDD at PK was found to be 39%–53% lower than TI and SC during running for all the PM fractions. Overall, the study findings show the air quality variation at different MEs and reveals the exposure inequalities around the city, which enable the management of personal exposure by selecting appropriate MEs for different activities.

Impacts of PM on Indoor Air Quality of Airport Terminal Buildings in a Core City of North China Plain

With the economic growth and globalization, a great deal of airports are being or planned to be constructed or retrofitted in China. The air quality in airport terminal buildings has not been studied as in-depth as airport ambient air quality. Due to its unique architectural and operational characteristics, the airport terminal buildings have individual performance of indoor air quality. The contribution of outdoor particulate matter (PM) to indoor environment and passengers’ exposure to indoor PM is not well understood. The indoor (i.e., terminal buildings) and outdoor PM concentrations with particle sizes from 0.25 to 32 μm of Tianjin Binhai International Airport (IATA: TSN) were monitored continuously during two cases in winter and summer 2020. Higher indoor PM concentrations occurred in winter as well as in the arrival halls of TSN. During winter case, the indoor sources contributed more to the indoor environment than the outdoor sources, whereas the opposite was found during summer case. Sharp variation of indoor PM number concentrations existed in particles within the range of 0.25–0.40 μm in size, with a peak number concentration at particle size of about 0.30 μm. PM with smaller particle sizes were more likely to enter the indoor environment from outdoor. The comprehensive exposure in the TSN terminal buildings was higher than those in the transportation microenvironments, residences and other buildings. Significant diurnal variations of Respiratory deposition dose (RDD) were observed under various exposure durations. Our results highlight the need for further monitoring and improving the air quality in the terminal buildings.

Characteristics of fine and ultrafine aerosols in the London underground

Underground railway systems are recognised spaces of increased personal pollution exposure. We studied the number-size distribution and physico-chemical characteristics of ultrafine (PM0.1), fine (PM0.1–2.5) and coarse (PM2.5–10) particles collected on a London underground platform. Particle number concentrations gradually increased throughout the day, with a maximum concentration between 18:00 h and 21:00 h (local time). There was a maximum decrease in mass for the PM2.5, PM2.5–10 and black carbon of 3.9, 4.5 and ~ 21-times, respectively, between operable (OpHrs) and non-operable (N-OpHrs) hours. Average PM10 (52 μg m−3) and PM2.5 (34 μg m−3) concentrations over the full data showed levels above the World Health Organization Air Quality Guidelines. Respiratory deposition doses of particle number and mass concentrations were calculated and found to be two- and four-times higher during OpHrs compared with N-OpHrs, reflecting events such as train arrival/departure during OpHrs. Organic compounds were composed of aromatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) which are known to be harmful to health. Specific ratios of PAHs were identified for underground transport that may reflect an interaction between PAHs and fine particles. Scanning transmission electron microscopy (STEM) chemical maps of fine and ultrafine fractions show they are composed of Fe and O in the form of magnetite and nanosized mixtures of metals including Cr, Al, Ni and Mn. These findings, and the low air change rate (0.17 to 0.46 h−1), highlight the need to improve the ventilation conditions.

Seasonal changes and respiratory deposition flux of PM2.5 and PM10 bound metals in Dhaka, Bangladesh

Due to rapid urbanization and fast economic development, aerosol pollution is a serious environmental issue, especially in Bangladesh. Based on bioaccessibility and respiratory deposition doses (RDD), health risks of PM2.5 and PM10 bound 15 (fifteen) metals were investigated at fourteen urban sites (roadside, marketplace, industrial, and commercial areas). Sampling campaigns were conducted over four seasons (winter, summer, rainy, and autumn) from December 2020 to November 2021. A beta attenuation mass analyzer measured particulate matter concentrations in ambient air. The metals in PM fractions were analyzed by X-ray fluorescence spectroscopy and inductively coupled plasma mass spectrometry (ICP-MS). The airborne trace metals (Cd, As, Zn, Pb, Cr, Cu, Ni) with high enrichment factors indicate anthropogenic sources. The positive matrix factorization (PMF) categorized these elements as originating from automobile exhaust, industrial emissions, and solid waste/coal combustion, whereas the geologic elements came from earth crust/soil dust. During the winter, most of the air mass trajectories arrived from India across the land (82%) and Indo Gangetic Plain (IGP) region to the sampling sites, which may have aided in the transport of pollutants. The deposition flux of metals illustrated that compared to PM2.5, PM10 deposited a higher amount of metals in the upper airways (81.96%).In comparison, PM2.5 accumulates more elevated amounts of metals in alveolar regions (11.77%), due to the ability of fine particles to penetrate deeper into the lower pulmonary region. Among age groups, an adult inhales a higher amount of metals than a child, on average 0.103 mg and 0.08 mg of metals per day via PM2.5, respectively. Acute health impacts are caused by the deposited cancer-causing metals in alveolar tissue, which circulates through the bloodstream and affects several organs. Prolonged exposure to these carcinogenic metals poses significant health risks.

A novel in-situ method to determine the respiratory tract deposition of carbonaceous particles reveals dangers of public commuting in highly polluted megacity

BackgroundExposure to air pollutants is one of the major environmental health risks faced by populations globally. Information about inhaled particle deposition dose is crucial in establishing the dose–response function for assessing health-related effects due to exposure to air pollution.ObjectiveThis study aims to quantify the respiratory tract deposition (RTD) of equivalent black carbon (BC) particles in healthy young adults during a real-world commuting scenario, analyze factors affecting RTD of BC, and provide key parameters for the assessment of RTD.MethodsA novel in situ method was applied to experimentally determine the RTD of BC particles among subjects in the highly polluted megacity of Metro Manila, Philippines. Exposure measurements were made for 40 volunteers during public transport and walking.ResultsThe observed BC exposure concentration was up to 17-times higher than in developed regions. The deposition dose rate (DDR) of BC was up to 3 times higher during commute inside a public transport compared to walking (11.6 versus 4.4 μg hr−1, respectively). This is twice higher than reported in similar studies. The average BC mass deposition fraction (DF) was found to be 43 ± 16%, which can in large be described by individual factors and does not depend on gender.ConclusionsCommuting by open-sided public transport, commonly used in developing regions, poses a significant health risk due to acquiring extremely high doses of carcinogenic traffic-related pollutants. There is an urgent need to drastically update air pollution mitigation strategies for reduction of dangerously high emissions of BC in urban setting in developing regions. The presented mobile measurement set-up to determine respiratory tract deposition dose is a practical and cost-effective tool that can be used to investigate respiratory deposition in challenging environments.

Size fraction of hazardous particulate matter governing the respiratory deposition and inhalation risk in the highly polluted city Delhi.

Delhi has been identified as one of the highly polluted cities in the world and recently associated with the highest population weighted PM2.5 concentration. However, the unavailability of the health risk estimations using long-term data for Indian cities has been pointed out as a hurdle in performing the correct assessment. The present work estimated deposition of particles in different regions of respiratory systems (head airway = 67% deposition for 2.5µm particles; tracheo-bronchiolar (TB) = 73% deposition for 1.0µm particles; alveolar (AL) = 17% deposition for 0.5µm, 0.25µm, and < 0.25µm particles) using PM samples collected at a breathing height of 1.5m near the major ring road in New Delhi (India). The calculated risk index (RI) varied considerably between winter (1.21 ± 0.26 to 1.33 ± 0.50) and pre-monsoon-southwest monsoon months (0.34 ± 0.08 to 0.96 ± 0.27). Respiratory deposition dose of nanosized particles (≤ 500nm) in the alveoli region of the lung was found to be considerable (35%) indicating the need for understanding the role of these particles in posing health risk. Although the calculated values of risk metric for exposures of PM-associated metals indicated no risk to IIT Delhi population (hazard quotient < 1 and excess risk of getting cancer < 10-6-10-9), continuous monitoring for particles of different sizes at inhalation height are required for protecting human health.

Exposure characteristics of ultrafine particles on urban streets and its impact on pedestrians.

In order to investigate the pedestrian exposure characteristics of ultrafine particles (UFPs) on urban streets, both mobile and fixed-point monitoring experiments were conducted. A generalized additive model and a respiratory deposition dose model were used to quantify the influencing factors and potential harm of UFPs, respectively. The results showed that UFPs' hotspots were more likely to manifest at places where vehicles tend to cluster, namely at road intersections and bus stops. The pedestrian bridge had the lowest number concentration of UFPs in comparison with the pedestrian crossing and underground passage at the same intersection. Aboveground, a "weekend effect" acting upon urban streets and evidence for periodicity at the intersections were found. The UFPs' number concentration was comprehensively explained-about 62.7% of its variation-by traffic volume, wind speed, temperature, and relative humidity. The UFPs were mainly deposited in the alveolar region of the respiratory system, but the deposition doses of males exceeded those of females under the same conditions. Based on these findings, the study also provides appropriate suggestions for better managing traffic pollution sources, traffic infrastructure, and traffic organization.

Particulate matter exposure at urban traffic intersection during haze episodes: A case study in Changsha.

Urban intersection has been identified as a major contributor to the total personal exposure and short-term high exposure of particulate matter (PM) in modern cities. The main aim of this study was to get a better understanding of the determinants of traffic-related PM temporal variations and personal exposure to PMs at a viaduct-covered intersection controlled by traffic signals during the winter haze episodes. A two-day field sampling campaign was conducted with a portable device during evening rush hour and measured the PMs in the 0.3-10 μm size range both on the surface crosswalk and underground passage. PM variations and related cumulative respiratory deposition dose (RDD) along two routes with six road crossing scenarios were estimated on a severe pollution day and a typical day for both adults and children, respectively. The PM concentration on the severe pollution day ranged 59.2-67.9 μg/m3 for PM1, 163.8-257.0 μg/m3 for PM2, and 258.2-469.1 μg/m3 for PM10, respectively, as compared to 47.9-57.9 μg/m3for PM1, 112.7-199.8 μg/m3 for PM2, and 151.0-301.0 μg/m3 for PM10 on the typical day, respectively. The variability could be explained largely by the built-up environment, traffic component, signal setting, and ventilation condition. Our data suggest that an appropriate setting of the traffic signal would help reduce the personal exposure dose on the surface crosswalk at urban intersections and the ventilation condition had a significant influence on local PM distributions inside the underground passage. Results here provide possible suggestions for the future design of a walkable city.

Exposure Assessment of Traffic-Related Air Pollution Based on CFD and BP Neural Network and Artificial Intelligence Prediction of Optimal Route in an Urban Area

Due to rapid global economic development, the number of motor vehicles has increased sharply, causing significant traffic pollution and posing a threat to people’s health. People’s exposure to traffic-related particulate matter with an aerodynamic diameter less than 2.5 μm (PM2.5) primarily occurs during commuting. Many studies have used exposure risk assessment models to assess the possible adverse effects of PM2.5, but few have used them to plan low-risk pathways for commuters. This study simulated the pollutant concentration distribution in an idealized urban area in different scenarios. We then used a back propagation (BP) neural network to predict the pollutant concentration. The commuter respiratory deposition dose was calculated based on the BP prediction results, and the respiratory deposition dose was converted into obstacles on the commuting map. Finally, the rapidly exploring random tree star (RRT*) algorithm was used to plan low-risk paths for commuters. The results indicate that pollutants discharged by cars and tree planting can significantly affect the pollutant concentration. A 30.25 μg/m3 increase in the pollutant concentration discharged by cars resulted in a 7~13 μg/m3 increase in the traffic-related air pollution concentration on sidewalks. Combining a computational fluid dynamics simulation, a BP neural network model, and the RRT* algorithm provides a system to plan low-risk paths for commuters. This work proposes artificial-intelligence-based models for calculating the exposure risk to traffic-related pollutants (PM2.5) and choosing a low-risk commuting path to ensure healthy travel.