Ultrafine Particle Concentrations Research Articles

Review on Sampling Methods and Health Impacts of Fine (PM2.5, ≤2.5 µm) and Ultrafine (UFP, PM0.1, ≤0.1 µm) Particles

Airborne particulate matter (PM) is of great concern in the modern-day atmosphere owing to its association with a variety of health impacts, such as respiratory and cardiovascular diseases. Of the various size fractions of PM, it is the finer fractions that are most harmful to health, in particular ultrafine particles (PM0.1; UFPs), with an aerodynamic diameter ≤ 100 nm. The smaller size fractions, of ≤2.5 µm (PM2.5; fine particles) and ≤0.1 µm (PM0.1; ultrafine particles), have been shown to have numerous linkages to negative health effects; however, their collection/sampling remains challenging. This review paper employed a comprehensive literature review methodology; 200 studies were evaluated based on the rigor of their methodologies, including the validity of experimental designs, data collection methods, and statistical analyses. Studies with robust methodologies were prioritised for inclusion. This review paper critically assesses the health risks associated with fine and ultrafine particles, highlighting vehicular emissions as the most significant source of particulate-related health effects. While coal combustion, diesel exhaust, household wood combustors’ emissions, and Earth’s crust dust also pose health risks, evidence suggests that exposure to particulates from vehicular emissions has the greatest impact on human health due to their widespread distribution and contribution to air pollution-related diseases. This article comprehensively examines current sampling technologies, specifically focusing on the collection and sampling of ultrafine particles (UFP) from ambient air to facilitate toxicological and physiochemical characterisation efforts. This article discusses diverse approaches to collect fine and ultrafine particulates, along with experimental endeavours to assess ultrafine particle concentrations across various microenvironments. Following meticulous evaluation of sampling techniques, high-volume air samplers such as the Chem Vol Model 2400 High Volume Cascade Impactor and low-volume samplers like the Personal Cascade Impactor Sampler (PCIS) emerge as effective methods. These techniques offer advantages in particle size fractionation, collection efficiency, and adaptability to different sampling environments, positioning them as valuable tools for precise characterisation of particulate matter in air quality research and environmental monitoring.

Ultrafine particle measurements in New York State

Measurements of ultrafine particles (UFP) over several years were carried out across seven different locations in New York State. The locations include urban background sites (Queens College and Albany), near road sites (Queens, Buffalo and Rochester) and rural sites (Pinnacle State Park and Whiteface Mountain). UFP at the urban background and near road sites generally show highest concentrations in the morning during the early commute period. Concentrations decrease during the day but increase again in the afternoon or evening period. Weekday concentrations are higher than on weekends. UFP correlates well with traffic related co-pollutants black carbon (BC) and nitrogen oxides (NOx). At the rural locations, UFP concentrations show less variation during the day with highest concentrations in the early afternoon to late evening hours particularly in spring. Seasonally, UFP concentrations across urban background and near road sites, are highest in winter (Dec, Jan, Feb) and lowest in summer (Jun, Jul, Aug). The variation in UFP concentration with temperature, relative humidity and wind speed was investigated. At the Queens College site, particle number concentrations in six different size fractions were measured using a TSI 3031 instrument. Annual average UFP concentrations at Queens College were found to decrease over time consistent with emission control strategies.

Indoor Emissions Contributed the Majority of Ultrafine Particles in Chinese Urban Residences.

Ultrafine particle (UFP) pollution should be controlled to reduce its effects on health. The design of control measures is limited owing to the uncertainty of source contributions in Chinese residences, where indoor UFP pollution is more severe than in Western residences. Herein, a source-specific, time-dependent UFP concentration model was developed by applying an infiltration factor model incorporating coagulation effects. A Monte Carlo framework with the UFP concentration model was employed to estimate the probabilistic distribution of source contributions in Chinese residences. The input parameter distributions were determined based on our survey and previous studies. The annually averaged indoor UFP concentration was estimated at (2.75 ± 1.71) × 104 #/cm3, ranging from 2.35 × 103 to 1.27 × 105 #/cm3 outside the kitchen, and at (5.48 ± 3.08) × 104 #/cm3, ranging from 2.90 × 103 to 1.94 × 105 #/cm3 in the kitchen. Indoor sources contributed more to indoor UFPs, accounting for 61% in the nonkitchen and 80% in the kitchen, surpassing their contribution to indoor PM2.5 in Chinese residences. Meanwhile, the indoor UFP emission contributions were higher than those in the United States, Canada, and Germany, owing to higher emissions from cooking and cigarette smoking. These results will aid in elucidating human exposure to UFPs and in designing more targeted control measures.

Effects of gamma radiation on the optical properties of ultrafine iron particle/polystyrene composites

The present research studied the influence of gamma radiation doses on the optical properties and parameters of the tested composite samples consisting of polystyrene polymer as a matrix filled with different concentrations of ultrafine iron particles (0, 10, 20, and 30 wt.%) with an average thickness of 2 µm. Using a UV-1800 Shimadzu spectrophotometer, the optical absorbance and transmittance values of the tested composite samples were measured at room temperature in the wavelength range of 200–800 nm. Optical parameters such as the excitation energy for electronic transitions, optical energy gap, dispersion energy, static dielectric constant, static refractive index, moments of the optical spectrum, optical oscillator strengths, linear optical susceptibility, third-order nonlinear optical susceptibility, carrier concentration to the effective mass ratio, high-frequency dielectric constant, nonlinear refractive index, plasma frequency and long wavelength refractive index were calculated and discussed at different doses of gamma radiation (1, 2, and 6 kGy). The results demonstrate that the optical properties and parameters of the gamma-irradiated composites vary with increasing gamma doses. This variation in values was observed after increased irradiation due to enhanced metal–polymer bonding and due to an increase in the density of the free charges within the metal polymer composites.

Fine Particle Formation and Dependence of Wet Deposition on Precipitation Intensity in an Urban Area

ABSTRACT In order to understand the characteristics of the change of aerosol concentration in an urban area and the impact of meteorological conditions on aerosol concentration in urban areas, particle concentration and size distribution were measured using an aerosol particle counter and an aerosol spectrometer in Hefei, China in spring 2017. Meteorological data, such as temperature, relative humidity, wind speed, wind direction, and shortwave radiation, were measured on a meteorological tower. The concentration of coarse mode (d > 2.5 μm, d is particle diameter), accumulation mode (0.25 μm<d < 2.5 μm), and ultrafine (Aitken and nucleation mode, d < 0.25 μm) particles under different meteorological conditions were recorded. Results show that, approximately 10–20 min after the solar downward shortwave radiation decreases (rises), the ultrafine particles (UFPs) concentration decreases (rises). Diurnal change in radiation causes daily change in the concentration of UFPs, and when the relative humidity was low, UFP generation easily occurs. On wet deposition, the concentration of coarse mode particles is significantly reduced during precipitation, and the concentration of accumulation mode particles varies during heavy precipitation and slight precipitation. Because of the combined action of wet deposition and hygroscopic growth, the concentration of accumulation mode particles first increases and then decreases. And during the slight precipitation, the concentration only increases with the relative humidity.

Determination of Occupational Exposure to Ultrafine Particles in Different Sectors of Activity

The primary sources of ultrafine particulate matter are linked to human activity. Certain particulate emissions, particularly those of a finer nature, can significantly impact human health, making them one of the most concerning pollutants. Ultrafine particles (UFPs), which have a diameter of less than 100 nm, are of particular concern due to their impact on human health and the difficulty in controlling them. The concentration of ultrafine particles (UFPs) in the workplace is a growing concern and is classified as an emerging risk. Workers may be exposed to UFPs through inhalation, skin absorption, ingestion, or a combination of these routes. This study aims to determine the levels of UFP exposure among workers in environments with varying direct particle emission patterns. Measurements were conducted to compare the results with the levels recommended by the WHO. The study monitored industrial workplaces with direct particulate matter emissions, such as a carpentry workshop and a bakery, as well as social sector sites without or almost without direct particle emissions, such as a school and a health clinic. One conclusion drawn from this study is that all tasks and occupations are susceptible to high levels of UFPs, exceeding WHO recommended values in virtually all monitored environments. Therefore, monitoring and controlling UFPs is crucial. Further in-depth studies on this subject are also necessary.

Health risk assessment of ultrafine particle movement in children's residential spaces based on probabilistic neural networks

The air quality in children's living spaces has a significant impact on their health, and ultrafine particulate matter (PM2.5), as one of the main pollutants in the air, poses a particularly prominent threat to children's respiratory and immune systems. Therefore, it important to conduct health risk assessment on ultrafine particle exercise in children's living spaces. In this article, an intelligent risk assessment model of ultrafine atmospheric particles in children's sports space in residential areas based on probabilistic neural network (PNN) is studied. This model utilizes probabilistic neural networks to monitor and predict ultrafine particles in residential spaces, evaluating their potential risks to children's health. By collecting relevant data such as particulate matter concentration and air quality index in residential spaces, and using probabilistic neural networks for training and prediction, accurate assessment of the health risks of ultrafine particulate matter during exercise can be achieved. This model can be applied to densely populated places such as families and schools, providing parents and relevant institutions with scientific risk warning and prevention measures to ensure the health and safety of children. Probabilistic neural networks can learn and simulate complex nonlinear relationships, making the model more accurate in predicting the concentration of ultrafine particles and health risks. So as to construct a method system of health risk assessment of atmospheric particles, and the model is heavy metal elements in atmospheric fine particles, and corresponding improvement measures are put forward according to the assessment results. For circulatory system diseases, the degree of harm of atmospheric temperature and fine particles to children's health is basically close, and with the continuous decline of temperature, the synergistic effect of the two is more obvious. The concentration of atmospheric ultrafine particles significantly affects the health risk of children's sports activities space. All the experiments in this article are quite good. Among them, the average accuracy of the PNN health risk identification model is 0.840, and the average recall rate is 0.837. The health risk assessment model in this article strengthens the correlation of data information through scientific methods, grasps the basic information of children's sports activity spaces in residential areas, and formulates targeted sports health risk assessments for children's sports activity spaces in residential areas. Compared with the comparison method, the response speed is significantly improved, with an accuracy rate of over 90%.

Spatial and temporal variation of cooking-emitted particles in distinct zones using scanning mobility particle sizer and a network of low-cost sensors

Exposure to ambient and household fine-particulate matter is identified as a substantial contributor to premature mortality in India, according to the Global Burden of Disease Studies. This study examines the impacts of typical Indian cooking practices on indoor air quality characteristics by monitoring the evolution of fine and ultrafine particle (UFP) concentration in the dining facility of a residential educational institute in India. The monitoring area was spread across the kitchen (zone 1) and the dining hall (zone 2). A combination of validated low-cost PM sensors (LCS), DustTrak8433, and Scanning Mobility Particle Sizer (SMPS) was utilized for real-time data acquisition while using Liquefied Petroleum Gas (LPG) as the cooking fuel. PM2.5 and UFP concentrations were monitored at 1.3 m and 1.8 m from the floor to assess the vertical variation of pollutants during cooking activities, including breakfast, lunch, and dinner, and processes such as preheating, reheating, stir-frying, and deep-frying. It was found that the prolonged cooking durations involved in high-heat cooking methods like stir-frying and deep-frying resulted in a rise in coarser UFP (300–550 nm) and PM2.5, causing a higher exposure to PM and UFP concentration. PM2.5 levels are higher at upper heights during typical cooking processes because of temperature-driven convection currents and hygroscopic growth of particles due to high humidity levels. Air exchange rates (AER) considerably varied by using chimneys and were low during the controlled (closed doors) compared to mixed ventilation (opened doors) conditions. The maximum AER was obtained during lunch (4.3–9.9 h−1) compared to breakfast (-7.8–6.8 h−1) and dinner (0.55–7.9 h−1). The decrement rate of PM2.5 inside zone 1 was highest during lunch (126 µgm−3 h−1), coinciding with the highest AER during mixed ventilation. It is recommended that improving ventilation and better design of the kitchen can reduce the exposure of PM and UFP in commercial and rural area kitchens.

Personal exposure to ultrafine particles in multiple microenvironments among adolescents.

Experimental studies suggest ultrafine particles (UFPs), the smallest size fraction of particulate matter, may be more toxic than larger particles, however personal sampling studies in children are lacking. The objective of this analysis was to examine individual, housing, and neighborhood characteristics associated with personal UFP concentrations as well as the differences in exposures that occur within varying microenvironments. We measured weekly personal UFP concentrations and GPS coordinates in 117 adolescents ages 13-17 to describe exposures across multiple microenvironments. Individual, home, and neighborhood characteristics were collected by caregiver completed questionnaires. Participants regularly exposed to secondhand tobacco smoke had significantly higher indoor concentrations of UFPs compared to participants who were not. We observed that the 'home' microenvironment dominated the relative contribution of overall UFP concentrations and sampling time, however, relative proportion of integrated UFP exposure were higher in 'other' environments. In this study, we employed a novel panel study design, involving real-time measurement of UFP exposure within the multiple microenvironments of adolescents. We found a combination of personal sampling and detailed activity patterns should be used in future studies to accurately describe exposure-behavior relationships.

Iodine oxoacids and their roles in sub-3 nm particle growth in polluted urban environments

Abstract. New particle formation contributes significantly to the number concentration of ultrafine particles (UFPs, d ≤ 100 nm) and has a great impact on human health and global climate. Iodine oxoacids (HIOx, including iodic acid, HIO3, and iodous acid, HIO2) have been observed in pristine regions and proved to dominate new particle formation (NPF) at some sites. However, the knowledge of HIOx in polluted urban areas is rather limited. Here, we conducted a long-term measurements of gaseous iodine oxoacids and sulfuric acid in Beijing from January 2019 to October 2021 and also in Nanjing from March 2019 to February 2020 and investigated the contribution of HIOx to UFP number concentration in both urban environments. HIO3 is highest in summer, up to 2.85 × 106 and 2.78 × 106 cm−3 in Beijing and Nanjing, respectively, and is lowest in winter by 96 % and 75 %, respectively. HIO3 exhibits more prominent variation than H2SO4 in both urban sites. HIO3 concentration shows a clear diurnal pattern at both sites with a daily maximum at around noontime, similar to the atmospheric temperature, solar radiation, and ozone (O3) levels. HIO2 concentration has the same diurnal and seasonal trend as HIO3 but is overall about an order of magnitude lower than HIO3 concentration. Back trajectory analysis suggests that the sources for inland iodine species could be a mix of marine and terrestrial origins, with both having peak iodine emission in warm seasons. While the contribution of HIO2 to particle growth is marginal in Beijing and Nanjing, our results demonstrate that HIO3 enhances the particle survival probability of sub-3 nm particles by about 40 % (median) and occasionally by more than 100 % in NPF events, suggesting HIOx are significant contributor to UFPs in polluted urban areas. As the growth contribution from HIO3 and H2SO4 is similar on a per-molecule basis, we propose that the sum of HIO3 and H2SO4 could be used to estimate sub-3 nm particle growth of inorganic acid origin in polluted atmospheres with a significant amount of HIOx.

Los Angeles Basin's air quality transformation: A long-term investigation on the impacts of PM regulations on the trends of ultrafine particles and co-pollutants

This study investigates the long-term trends of ambient ultrafine particles (UFPs) and associated airborne pollutants in the Los Angeles Basin from 2007 to 2022, focusing on the indirect effects of regulations on UFP levels. The particle number concentration (PNC) of UFPs was compiled from previous studies in the area, and associated co-pollutant data, including nitrogen oxides (NOx), carbon monoxide (CO), elemental carbon (EC), organic carbon (OC), and ozone (O3), were obtained from the chemical speciation network (CSN) database. Over the study period, a general decrease was noted in the PNC of UFPs, NOx, EC, and OC, except for CO, the concentration trends of which did not exhibit a consistent pattern. UFPs, NOx, EC, and OC were positively correlated, while O3 had a negative correlation, especially with NOx. Our analysis discerned two distinct sub-periods in pollutant trends: 2007–2015 and 2016–2022. For example, there was an overall decrease in the PNC of UFPs at an annual rate of −850.09 particles/cm3/year. This rate was more pronounced during the first sub-period (2007–2015) at −1814.9 particles/cm3/year and then slowed to −227.21 particles/cm3/year in the second sub-period (2016–2023). The first sub-period (2007–2015) significantly influenced pollutant level changes, exhibiting more pronounced and statistically significant changes than the second sub-period (2016–2022). Since 2016, almost all primary pollutants have stabilized, indicating a reduced impact of current regulations, and emphasizing the need for stricter standards. In addition, the study included an analysis of Vehicle Miles Traveled (VMT) trends from 2007 to 2022 within the Los Angeles Basin. Despite the general increase in VMT, current regulations and cleaner technologies seem to have successfully mitigated the potential increase in increase in PNC. Overall, while a decline in UFPs and co-pollutant levels was observed, the apparent stabilization of these levels underscores the need for more stringent regulatory measures and advanced emission standards.

Analysing the impact of day-night road traffic variation on ultrafine particle number size distribution and concentration at an urban site in the megacity Delhi

Air quality is the biggest threat in many urban cities globally. This study measured and analyzed aerosol number size distribution between 10 to 1090 nm in the megacity Delhi during 2022. The study examined the particle number concentration in the ultrafine (<100 nm) and accumulation (100–1000 nm) ranges during day and night in terms of source's intensity, emission patterns and local meteorological conditions. Nucleation mode particles (Nnuc, 10–30 nm) contributed ∼50 % during daytime in summer periods due to increased fresh traffic emissions. In the daytime, particle concentration was dominated by smaller sizes, such as Nnuc and Aitken mode particles (Natk, 30–100 nm), while in the nighttime, the particles were found in Aitken and Accumulation (Nacc, 100–1000 nm) modes. Nnuc and Natk were reduced by ∼45 % and 4 % at night, while Nacc increased by ∼34 %. The mean normalized aerosol number size distribution confirmed these findings, showing clearly that Nnuc dominated during the daytime, especially during peak rush hours, and during the night particles concentration was increased up to the sizes of 300 nm particles. The aerosol number size distribution and the changes experienced in the percentage of the concentration of the different particle size ranges highlight the role of engine exhaust emissions in the atmospheric aerosol population in urban areas. The findings of the study help to identify the different source's intensity and behavior during day and nighttime, which can be used for policy formulation and decision-making to mitigate air quality and its associated health impacts.

Multi-season mobile monitoring campaign of on-road air pollution in Bengaluru, India: High-resolution mapping and estimation of quasi-emission factors

Mobile monitoring can supplement regulatory measurements, particularly in low-income countries where stationary monitoring is sparse. Here, we report results from a ~ year-long mobile monitoring campaign of on-road concentrations of black carbon (BC), ultrafine particles (UFP), and carbon dioxide (CO2) in Bengaluru, India. The study route included 150 unique kms (average: ~22 repeat measurements per monitored road segment). After cleaning the data for known instrument artifacts and sensitivities, we generated 30 m high-resolution stable ‘data only’ spatial maps of BC, UFP, and CO2 for the study route. For the urban residential areas, the mean BC levels for residential roads, arterials, and highways were ~ 10, 22, and 56 μg m−3, respectively. A similar pattern (highways being characterized by highest pollution levels) was also observed for UFP and CO2. Using the data from repeat measurements, we carried out a Monte Carlo subsampling analysis to understand the minimum number of repeat measures to generate stable maps of pollution in the city. Leveraging the simultaneous nature of the measurements, we also mapped the quasi-emission factors (QEF) of the pollutants under investigation. The current study is the first multi-season mobile monitoring exercise conducted in a low or middle -income country (LMIC) urban setting that oversampled the study route and investigated the optimum number of repeat rides required to achieve representative pollution spatial patterns characterized with high precision and low bias. Finally, the results are discussed in the context of technical aspects of the campaign, limitations, and their policy relevance for our study location and for other locations. Given the day-to-day variability in the pollution levels, the presence of dynamic and unorganized sources, and active government pollution mitigation policies, multi-year mobile measurement campaigns would help test the long-term representativeness of the current results.

Introducing the novel concept of cumulative concentration roses for studying the transport of ultrafine particles from an airport to adjacent residential areas

Abstract. Airports are often surrounded by urban residential areas, which is both a motivation and challenge for studying their potential impact on local air quality. Airports are a relevant source of ultrafine particles (UFPs), which can pose a risk to human health due to their small size (particle diameter Dp≤100 nm). However, in urban environments, UFPs originate from a multitude of biogenic and anthropogenic sources. Here, we investigate UFPs in close proximity to an airport to disentangle their impact on local air quality from other urban sources. We present observations and analyses of airborne UFP concentrations and size distributions determined at two sites in close proximity to Munich Airport. Therefore, two novel measurement stations were established north and south of the airport but were neither situated on the axis of prevailing wind directions nor impacted by fly overs. This set-up allowed us to explore a mainly advection-driven distribution of UFPs into the most populated adjacent residential areas. The observation period covered a full year from August 2021 to July 2022. We analysed the data set in three steps. (1) First, we derived UFP concentration roses using the wind data as reported at 10 m height at the airport to represent the local wind field. An increase in particle number concentrations and a shift of the modal maximum towards smaller mobility diameters became evident for wind directions, including those approaching from the airport. During the airport's operation hours during the daytime, median particle number concentrations were 2.2- and 1.6-fold compared to nighttime at the northern station and the southern station. However, our data had a high variability, and the direction-based analysis was uncertain due to other potential UFP sources in the surroundings and the assumption of a homogeneous, local wind field. (2) Next, we derived concentration roses employing the airflow observations from the two measuring stations at 5.3 m height. While the annual concentration rose in principle yielded the same conclusions as the first analysis step, a significant seasonal and diurnal variability of UFPs and wind became evident. The influencing factors were likely other urban local UFP sources, an increased surface roughness due to green vegetation, and the atmospheric boundary layer development. (3) In order to assess the possible advection of UFPs from the direction of Munich Airport relative to all other directions over the course of the year, we calculated cumulative concentration roses with both local- and site-scale wind data. Under the assumption of a homogeneous local wind field, the fraction of all UFPs sampled in airflows approaching from the airport's direction was 21 % (N322) and 40 % (S229). Considering a local background, the range of UFP advection from Munich Airport to the adjacent residential areas was up to 10 % in the north and 14 % in the south. It has to be noted that these values highlight the relative magnitude of the maximum impact of the airport on local air quality as they do not distinguish between UFP sources from the airport and other measuring sites. Additionally, they integrate over a time period during which the airport did not reach its full capacity compared to pre-COVID-19 times.

Exploratory measurements of ambient air quality in a residential area applying a diffusion charge based UFP monitor/Orientierende Messungen der Luftqualität in einem Wohngebiet mit einem auf Diffusionsaufladung basierten UFP-Monitor

In the context of the revision of the EU Ambient Air Qualitiy Directive (2008/50/EC), measurement of ultrafine particles (UFP) in ambient air is proposed and discussed. To investigate the local ambient UFP concentration (immis- sion), exploratory measurements of air pollution with UFPs were performed over several months in a residential area. The measurement device is based on charge detection of the measurement aerosol (AQ Guard Smart 2000 of the manufacturer Palas®). The background particle concentrations are within the typical background level for rural residential areas (3,000 to 5,000 cm-3). Increased UFP concentration levels were predominantly measured during the evening and the night. On 53 days of the total measurement duration of 101 days increased par- ticle concentrations above the background level (at least 6,000 cm-3) regarding the 15-minute average values were measured for at least one hour during the evening and night (16:00 to 0:00). The main source of the increased particle concentra- tion is the operation of woodstoves in the neighbourhood of the measuring location. This air pollution in the evening hours is not reflected in the context of daily or monthly averages. Other pollution sources (barbecue, new-years fireworks, traffic – different measurement location) were also identified and differences of the mean particle diameter of the ambient aerosol with regards to the background level (80 nm) could be determined. The device is suitable for UFP measurements and offers a lower detectable size-range compared to conventional scattered-light based optical particle counters.

Ultrafine Particles on Electric, Gas, and Diesel Buses in the Mass Transit Buses of Bogotá, Colombia

The concentration of traffic-related air pollutants (TRAPs) inside transport microenvironments takes on relevance today in many megacities with high population density, intense traffic, and prolonged travel times. These conditions can intensify exposure to TRAPs and worsen public health problems. TRAP concentrations in these microenvironments are changing because of the introduction of cleaner technologies. In this study, we compare the ultrafine particles measured inside diesel, gas, and electric buses during their normal operation in Bogotá, Colombia. We used a miniature diffusion size classifier (DiSCmini) to measure ultrafine particle concentrations, average particle size, and the lung-deposited surface area. Our results revealed significantly lower levels of this pollutant inside electric buses. The concentration of ultrafine particles per cubic centimeter is about 41% and 27% lower in electric buses compared to diesel and gas, respectively. The lung-deposited surface area is also lower in electric buses. Nevertheless, the average particle size in electric buses is 10% and 18% smaller compared to diesel and gas, respectively.

Regenerative braking system effectively reduces the formation of brake wear particles

Brake wear particles (BWPs) are considered one of the most significant non-exhaust particle emission sources from motor vehicles. Previous studies have primarily focused on BWPs from conventional fuel vehicles (CFVs), with limited research available on BWPs from new energy vehicles (NEVs). We developed an independent BWP emission testing system applicable to NEVs and conducted BWP emission tests on representative NEVs and CFVs under various testing cycles via a chassis dynamometer. The BWP emission characteristics of the NEVs equipped with regenerative braking system significantly differed from those of gasoline vehicles. For transient emission characteristics, gasoline vehicles exhibited higher peak concentrations during brake events than brake drag events, while those with regenerative braking exhibited the opposite feature. Under continuous braking, the concentration of ultrafine particles emitted by NEVs was reduced by more than 3 orders of magnitude compared to gasoline vehicles. In terms of single-particle morphology, BWPs could be mainly divided into three categories: carbonaceous particles, iron-rich particles, and mixed metal particles. We obtained realistic emission characteristics of BWPs from NEVs, which could provide data support and a scientific basis for the formulation of relevant emission standards and control measures in the future.

Long-term exposure to ambient air pollution and inflammatory response in the KORA study

Previous studies consistently showed an association between fine atmospheric particulate matter (PM2.5) and cardiovascular diseases. Concerns about adverse health effects of ultrafine particles (UFP) are growing but long-term studies are still scarce. In this study, we examined the association between long-term exposure to ambient air pollutants and blood biomarkers of inflammation and coagulation, including fibrinogen, high-sensitivity C-reactive protein (hs-CRP), serum amyloid A (SAA) adiponectin and interleukin-6 (IL-6), measured in the German KORA-S4 cohort study (1999–2001). IL-6 was available for older participants only, who were therefore considered as a subsample. Annual mean concentrations of UFP (as particle number concentration), particulate matter in different particles sizes (PM10, PMcoarse, PM2.5, PM2.5 absorbance), ozone (O3), and nitrogen oxides (NO2, NOX) were estimated by land-use regression models and assigned to participants' home addresses. We performed a multiple linear regression between each pollutant and each biomarker with adjustment for confounders. Per 1 interquartile range (IQR, 1945 particles/cm3) increase of UFP, fibrinogen increased by 0.70 % (0.04; 1.37) and hs-CRP increased by 3.16 % (−0.52; 6.98). Adiponectin decreased by −2.53 % (−4.78; −0.24) per 1 IQR (1.4 μg/m3) increase of PM2.5. Besides, PM2.5 was associated with increased IL-6 in the subsample. In conclusion, we observed that long-term exposure to air pollutants, including both fine and ultrafine particles, was associated with higher concentrations of pro-inflammatory and lower concentrations of an anti-inflammatory blood biomarkers, which is consistent with an increased risk for cardiovascular disease observed for long-term exposure to air pollutants.

Associations between ultrafine particle pollution and daily outpatient visits for respiratory diseases in Shanghai, China: a time-series analysis

Previous epidemiological studies have linked short-term exposure to particulate matter with outpatient visits for respiratory diseases. However, evidence on ultrafine particle (UFP) is still scarce in China. To investigate the association between short-term UFP exposure and outpatient visits for respiratory diseases as well as the corresponding lag patterns, information on outpatient visits for main respiratory diseases during January 1, 2017, to December 31, 2019 was collected from electronic medical records of two large tertiary hospitals in Shanghai, China. Generalized additive models employing a Quasi-Poisson distribution were employed to investigate the relationships between UFP and respiratory diseases. We computed the percentage change and its corresponding 95% confidence interval (CI) for outpatient visits related to respiratory diseases per interquartile range (IQR) increase in UFP concentrations. Based on a total of 1,034,394 hospital visits for respiratory diseases in Shanghai, China, we found that the strongest associations of total UFP with acute upper respiratory tract infection (AURTI), bronchitis, chronic obstructive pulmonary disease (COPD), and pneumonia occurred at lag 03, 03, 0, and 03 days, respectively. Each IQR increase in the total UFP concentrations was associated with increments of 9.02% (95% CI: 8.64–9.40%), 3.94% (95% CI: 2.84–5.06%), 4.10% (95% CI: 3.01–5.20%), and 10.15% (95% CI: 9.32–10.99%) for AURTI, bronchitis, COPD, and pneumonia, respectively. Almost linear concentration–response relationship curves without apparent thresholds were observed between total UFP and outpatient-department visits for four respiratory diseases. Stratified analyses illustrated significantly stronger associations of total UFP with AURTI, bronchitis, and pneumonia among female patients, while that with COPD was stronger among male patients. After adjustment of criteria air pollutants, these associations all remained robust. This time-series study indicates that short-term exposure to UFP was associated with increased risk of hospital visits for respiratory diseases, underscoring the importance of reducing ambient UFP concentrations for respiratory diseases control and prevention.

High exposure of ultrafine particles at Guangzhou bus stops and the impact of urban layout

Urban bus stops have been identified as hotspots for particulate matter due to intense vehicle activities, including acceleration from standstill, this poses a risk of short-term exposure to high levels of pollution for residents who wait for buses during their daily commute. In order to provide constructive and scientific recommendations for the placement of bus stops from the perspective of regional architectural layout, we conducted a comparative observational experiment in Guangzhou to investigate the exposure to ultrafine particle (UFP) at bus stations with different building layouts. Our study found that there was a significant interaction between the urban layout and vehicle activities of bus stations with 99% confidence level. The average level of UFP pollution at the street canyon bus stations was 48.2 103ptccm−1 in the afternoon. Pedestrians waiting at the bus stations built in the street canyon could be exposed to excessive UFP levels (higher than 30.0103ptccm−1) during 82.2% of the waiting time. Compared to the park, the UFP concentration at the bus station in the canyon was found to be more responsive to changes in traffic volume, and the diffusion of UFP was more dependent on meteorological conditions, according to the results of grey relational analysis. However, near the park, there was no significant difference in UFP levels with and without the bus station. Based on our findings, we recommend that the department of urban planning and design consider creating a more open diffusion environment when setting up bus stops to reduce the risk of exposure to high level of UFP pollution.