Ultrafine Particle Concentrations Research Articles

Hourly Ultrafine Particle Exposure and Acute Myocardial Infarction Onset: An Individual-Level Case-Crossover Study in Shanghai, China, 2015–2020

Associations between ultrafine particles (UFPs) and hourly onset of acute myocardial infarction (AMI) have rarely been investigated. We aimed to evaluate the impacts of UFPs on AMI onset and the lag patterns. A time-stratified case-crossover study was performed among 20,867 AMI patients from 46 hospitals in Shanghai, China, between January 2015 and December 2020. Hourly data of AMI onset and number concentrations of nanoparticles of multiple size ranges below 0.10 μm (0.01-0.10, UFP/PNC0.01-0.10; 0.01-0.03, PNC0.01-0.03; 0.03-0.05, PNC0.03-0.05; and 0.05-0.10 μm, PNC0.05-0.10) were collected. Conditional logistic regressions were applied. Transient exposures to these nanoparticles were significantly associated with AMI onset, with almost linear exposure-response curves. These associations occurred immediately after exposure, lasted for approximately 6 h, and attenuated to be null thereafter. Each interquartile range increase in concentrations of total UFPs, PNC0.01-0.03, PNC0.03-0.05, and PNC0.05-0.10 during the preceding 0-6 h was associated with increments of 3.29, 2.08, 2.47, and 2.93% in AMI onset risk, respectively. The associations were stronger during warm season and at high temperatures and were robust after adjusting for criteria air pollutants. Our findings provide novel evidence that hourly UFP exposure is associated with immediate increase in AMI onset risk.

Phenomenology of ultrafine particle concentrations and size distribution across urban Europe

The 2017–2019 hourly particle number size distributions (PNSD) from 26 sites in Europe and 1 in the US were evaluated focusing on 16 urban background (UB) and 6 traffic (TR) sites in the framework of Research Infrastructures services reinforcing air quality monitoring capacities in European URBAN & industrial areaS (RI-URBANS) project. The main objective was to describe the phenomenology of urban ultrafine particles (UFP) in Europe with a significant air quality focus.The varying lower size detection limits made it difficult to compare PN concentrations (PNC), particularly PN10-25, from different cities. PNCs follow a TR > UB > Suburban (SUB) order. PNC and Black Carbon (BC) progressively increase from Northern Europe to Southern Europe and from Western to Eastern Europe. At the UB sites, typical traffic rush hour PNC peaks are evident, many also showing midday-morning PNC peaks anti-correlated with BC. These peaks result from increased PN10-25, suggesting significant PNC contributions from nucleation, fumigation and shipping.Site types to be identified by daily and seasonal PNC and BC patterns are: (i) PNC mainly driven by traffic emissions, with marked correlations with BC on different time scales; (ii) marked midday/morning PNC peaks and a seasonal anti-correlation with PNC/BC; (iii) both traffic peaks and midday peaks without marked seasonal patterns. Groups (ii) and (iii) included cities with high insolation.PNC, especially PN25-800, was positively correlated with BC, NO2, CO and PM for several sites. The variable correlation of PNSD with different urban pollutants demonstrates that these do not reflect the variability of UFP in urban environments. Specific monitoring of PNSD is needed if nanoparticles and their associated health impacts are to be assessed. Implementation of the CEN-ACTRIS recommendations for PNSD measurements would provide comparable measurements, and measurements of <10 nm PNC are needed for full evaluation of the health effects of this size fraction.

Ultrafine Particles in Viennese Gastronomy after Introduction of a National Smoking Ban

Background: Ultrafine particles have a substantial influence on the pathogenesis of diseases from ambient air pollution including personal and indoor tobacco smoke. In public rooms such as gastronomy venues without complete smoking ban, the main source of ultrafine particles is cigarette smoke. Objectives: In accordance with the research question if the legislative smoking ban reduced ultrafine particle pollution in Viennese bars, cafés and pubs, the effectiveness of this ban for the protection of nonsmokers was evaluated. As a further objective, the comparison with the ultrafine particle concentrations in smoking and non-smoking areas before and after the general smoking ban was relevant, whereby the data from the survey period April to October 2019 were used. Hereby, the effectiveness of the measure could be derived from the direct comparison of the earlier and the current recordings. Methods: 2 years after the national Non-Smoking Protection Law in November 2019 had gone into force, the indoor exposures with ultrafine particles were surveyed in 22 Viennese bars/discotheques, 5 cafés and 12 pubs/restaurants and bars. By unannounced and undercover measurements over 20 minutes each, these well frequented gastronomy locations were investigated between October 2021 and February 2022. The concentration of ultrafine particles (PNC, pt/cm³), the corresponding diameter (10 - 300 nm) and lung deposited surface area (LDSA) were recorded via Miniature Diffusion Size Classifier (miniDiSC®) in all three types of locations. Results: The ultrafine particle loadings in 2021/22 in the three location types were not significantly different any more. Two years after the ban the median PNC (pt/cm³) was 19,751 in bars, 18,854 in cafés and 19,357 in pubs. The average diameter (AD, nm) was 54.17 in bars, 44.27 in cafés and 52.08 in pubs. For average LDSA (µm²/cm³), the values were 51.65 in bars, 35.76 in cafés, and 60.71 in pubs. 2019 data had shown significantly higher median values for PNC (pt/cm³) for smoking locations at 72,802 versus non-smoking areas at 27,776 and non-smoking locations at 18,854. Similarly, smoking locations showed significantly higher values for AD (nm) at 78 versus non-smoking areas at 62 and non-smoking locations at 52. For average LDSA (µm²/cm³), smoking locations also had the highest values at 402.0 versus non-smoking areas at 108.0 and non-smoking locations at 51.9. From comparison of data, it was possible to derive the UFP concentrations above which a hospitality indoor area - regardless of its declared status - may be classified as polluted by nanoparticles (tobacco smoke): For PNC, 34,435 pt/ cm³, for average diameter 67.45 nm and for LDSA 163.68 µm²/cm³ are proposed as cut-off values. Conclusion: The national smoking ban significantly improved air quality in Viennese hospitality venues. Two years after the ban ultrafines were comparably low and not significantly different between bars, cafés and pubs, whether they were used before for smoking or not. The decrease of ultrafine particle pollution was attributed to regular non-smoking in localities. Some outliers of the present investigation after the smoking ban indicated, that control of compliance with the law has to be continued.

Covid –19 restrictions expose air traffic at the Munich Airport as hotspot of ultrafine particle pollution – implications for regional air quality/Covid-19 Restriktionen entlarven den Flugverkehr am Flughafen München als größte Quelle der Ultrafeinstaubbelastung – Implikationen für die regionale Luftqualität

The massive decline of air traffic in consequence of the Covid-19 pandemic allowed a detailed analysis of aviation induced noise and particularly air pollution caused by kerosene combustion. As expected, aircraft noise is reduced significantly particularly during daytime. Notably, the particulate matter PM2.5 and PM10 officially measured as pollution load at airports is proven to be almost unchanged in ambient air. As jets do not emit coarse fine dust but solely ultrafine particles smaller than 0.1 µm (UFP), this result is no surprise. However, the dramatic reduction of ultrafine particle concentration under reduced air traffic is exemplified e.g. by 7,100 UFP/cm3 in April 2020 while in February 2020 at the Munich Airport center still 54,200 UFP/cm3 were measured. Assuming an UFP background concentration of 5,000 UFP/cm3, a decline of air traffic by 93% reduced UFP by the same magnitude. Measuring the downwind plume of the airport at varying distances the number of particles decreases while the particle size increases which is based on the fact that aircrafts emit only smallest UFP which intermix with bigger UFP from other sources around the airport. Effective measures to prevent UFP emissions are urgently needed. In addition to the use of sulfur-free kerosene, towing the aircraft during all taxiing procedures is the most effective measure to reduce UFP on ground. This work fostered the development of https://10nm.de/, which intends to provide a simulation of the potential UFP load at any airport based on wind conditions like wind direction and wind speed.

Nucleation of jet engine oil vapours is a large source of aviation-related ultrafine particles

Large airports are a major source of ultrafine particles, which spread across densely populated residential areas, affecting air quality and human health. Jet engine lubrication oils are detectable in aviation-related ultrafine particles, however, their role in particle formation and growth remains unclear. Here we show the volatility and new-particle-formation ability of a common synthetic jet oil, and the quantified oil fraction in ambient ultrafine particles downwind of Frankfurt International Airport, Germany. We find that the oil mass fraction is largest in the smallest particles (10-18 nm) with 21% on average. Combining ambient particle-phase concentration and volatility of the jet oil compounds, we determine a lower-limit saturation ratio larger than 1 × 105 for ultra-low volatility organic compounds. This indicates that the oil is an efficient nucleation agent. Our results demonstrate that jet oil nucleation is an important mechanism that can explain the abundant observations of high number concentrations of non-refractory ultrafine particles near airports.

Exposure to ambient ultrafine particles and allergic sensitization in children up to 16 years

BackgroundFew epidemiological studies so far have investigated the role of long-term exposure to ultrafine particles (UFP) in inhalant and food allergy development. ObjectivesThe purpose of this study was to assess the association between UFP exposure and allergic sensitization to inhalant and food allergens in children up to 16 years old in the Netherlands. Methods2295 participants of a prospective birth cohort with IgE measurements to common inhalant and food allergens at ages 4, 8, 12 and/or 16 were included in the study. Annual average UFP concentrations were estimated for the home addresses at birth and at the time of the IgE measurements using land-use regression models. Generalized estimating equations were used for the assessment of overall and age-specific associations between UFP exposure and allergic sensitization. Additionally, single- and two-pollutant models with NO2, PM2.5, PM2.5 absorbance and PM10 were assessed. ResultsWe found no significant associations between UFP exposure and allergic sensitization to inhalant and food allergens (OR (95% CI) ranging from 1.02 (0.95–1.10) to 1.05 (0.98–1.12), per IQR increment). NO2, PM2.5, PM2.5 absorbance and PM10 showed significant associations with sensitization to food allergens (OR (95% CI) ranging from 1.09 (1.00–1.20) to 1.23 (1.06–1.43) per IQR increment). NO2, PM2.5, PM2.5 absorbance and PM10 were not associated with sensitization to inhalant allergens. For NO2, PM2.5 and PM2.5 absorbance, the associations with sensitization to food allergens persisted in two-pollutant models with UFP. ConclusionThis study found no association between annual average exposure to UFP and allergic sensitization in children up to 16 years of age. NO2, PM2.5, PM2.5 absorbance and PM10 were associated with sensitization to food allergens.

Characterization of aerosols generated by high-power electronic nicotine delivery systems (ENDS): Influence of atomizer, temperature and PG:VG ratios.

The aerosol characteristics of electronic nicotine delivery systems (ENDS) are important parameters in predicting health outcomes since parameters such as aerosol particle size correlate strongly to aerosol delivery and deposition efficiency. However, many studies to date do not account for aerosol aging, which may affect the measurement of ultra-fine particles that typically coagulate or agglomerate during puff development. To reduce aerosol aging, we herein present a unique instrumentation method that combines a) positive pressure ENDS activation and sample collection, b) minimization of both sample tubing length and dilution factors, and c) a high-resolution, electrical low-pressure impactor. This novel approach was applied to systematically investigate the effects of coil design, coil temperature, and propylene glycol to vegetable glycerol ratios on aerosol characteristics including aerosol mass generation, aerosol count generation, and the mass and count size distributions for a high-powered ENDS. Aerosol count measurements revealed high concentrations of ultra-fine particles compared to fine and coarse particles at 200°C, while aerosol mass measurements showed an increase in the overall aerosol mass of fine and coarse particles with increases in temperature and decreases in propylene glycol content. These results provide a better understanding on how various ENDS design parameters affect aerosol characteristics and highlight the need for further research to identify the design parameters that most impact ultra-fine particle generation.

Contribution of Airplane Engine Emissions on the Local Air Quality around Stuttgart Airport during and after COVID-19 Lockdown Measures

Air quality investigations at airports have shown that aircrafts cause a significant increase in air pollution at and around the vicinity of the airport, which can cause adverse effects on human health. The objective of this research was to investigate the aircraft-sourced pollutant levels at the Stuttgart airport and in the surrounding areas during and after COVID-19 lockdown measures. Three phases of stationary measurements of ultrafine particles (UFP), particulate matter (PM), black carbon (BC), CO2, O3, NO, and NO2 were made at various points on the east and west sides of the airport in the extension of the airport runway. In first phase of measurement, the airport was closed for construction, and no air traffic took place. In the second phase, the airport was reopened with limited operation due to a lockdown period at the beginning of the COVID-19 pandemic. Finally, in the third phase, measurements were performed during the peak summer holiday travel season to measure the air quality during maximum air traffic, after the end of the first lockdown period. While there were fewer notable changes in the BC concentrations, coarse PM fractions, and gases across the three phases, there were significant increases in the UFP concentrations from aircraft emissions. Throughout the three phases, the peak particle concentration decreased from between 27 and 86 nm in phase 1. to between 27 and 35 nm in phase 2, to finally 11 nm in phase 3 on all days in which the aircraft plumes were measured. During flight arrivals, definite increases in UFP particle number concentration (PNC) were observed, with the majority of the particles being in the 10 nm size class. These results were measured repeatedly on both sides of the airport in the direct prolongation of the runway and even at distances of up to 3 km away in nearby neighbouring communities. While the overall PM and UFP levels are affected by vehicular traffic, the freeway measurements showed particles from aircrafts and vehicles are distinguishable using the parameters PNC and Dp. The BC concentrations were rarely influenced by aircraft activity, while only some NO and NO2 peaks were measured depending on the consistency of the wind.

Impact of the closure of Berlin-Tegel Airport on ultrafine particle number concentrations on the airfield

Airports contribute substantially to ultrafine particle (UFP; &amp;lt;100 nm) concentrations on a local scale. These UFPs, which derive mainly from combustion processes, are generated during take-off and landing of aircraft, during aircraft movements on the tarmac, when engines and turbines are started, and by vehicles transporting goods and people on the airfield. UFPs are considered particularly harmful to human health as their small size enables them to pass far into the human body. This study investigates the extent to which particle number concentrations (PNCs) sized 7–2,000 nm respond to the cessation of air traffic due to the closure of a major airport. PNCs and wind data were monitored with a 5 s resolution at one location on the airfield of Berlin-Tegel Airport (TXL). The station was located 600 –640 m east of the runways and thus downwind of the runways for the predominant wind direction. Observations took place 24 h per day every day for about 3 weeks before and 3 weeks after the closure of the airport. During the measurement campaign, a total of 2,507 take-offs and landings took place. Including all wind directions, this study shows 30 %–40% lower PNCs on average, 2.5-fold lower maximum values as well as a 3-fold lower PNC spread after the closure of the airport. These differences are evident only during the day with active flight operations, and not during the nighttime flight ban. Downwind of the airfield, differences are even higher. After the closure of the airport, average PNCs drop by 70%, maxima by 85%, and variability is reduced by almost 90%. 70% lower and 30% less frequent PNC peaks occur downwind of the airport after flight operations are discontinued. This unique natural experiment allows for relatively clear conclusions about the relevance of airport operations on PNCs in the airfield area. The measurements carried out before and after the closure allow a direct comparison of the PNCs during airport operations and without any. Thus, our study reveals the change in UFP concentration that can be achieved through a reduction in flight operations.

Concentration, chemical composition and toxicological responses of the ultrafine fraction of urban air particles in PM1

Epidemiological and toxicological evidence show that PM1 is a key driver of PM2.5. However, the particle sizes that play the major damaging role in PM1 is unclear. Our aims were to (1) explore the concentration and chemical composition of ultrafine particles in PM1; (2) evaluate and compare the differences in toxicity of PM1-0.2 and PM0.2 to different airway cell models. We collected PM1-0.2 and PM0.2 in Guangzhou in December 2017, monitored and detected their concentrations, size, and components. A549, THP-1 mono-cultures and A549/THP-1 co-cultured cells were exposed to PM1-0.2 and PM0.2, and evaluated for toxicological responses. PM0.2 contributed to15% PM1 mass and 87.67% to particle number (PN). Most of PM0.2 was PM0.1 (exceed 75%). Structure of particles in PM0.2 were mostly spherical, whereas in PM1-0.2 they were more diverse. Within the same mass unit, PM0.2 contained more chemical components than PM1-0.2; within the same volume, a higher mass of components was found in PM1-0.2. IL-6 and IL-8 were secreted by co-cultured cells in higher manner compared to mono cell cultures. PM0.2-induced higher toxicological responses compared to PM1-0.2. Our findings suggest that high PN concentration and toxicity of ultrafine or PM1 cannot be ignored. Mono-cell culture may underestimate the true PM toxicity.

Interaction between two car models with application to pollutant dispersion

Nowadays, air quality monitoring is a major concern. Among pollutants, exhaust UltraFine Particles (UFP) have a harmful effect on health due to their small size and to their ability to penetrate the bloodstream, the respiratory system, the brain as well as the placental barrier. Out of the industrial emissions, road traffic is a major source of air pollution. UFP emitted from the cars can infiltrate the car cabin through leakages and ventilation system leading to poor air quality in the passenger compartment. Improving the knowledge regarding the dispersion of exhaust UFP in the wake of a car considering road traffic is then mandatory. In this paper, the dispersion of UFP is studied in the wake of a leading vehicle (LV) followed by a second one. Two rear slant angles (φ) for LV and 6 inter-vehicle distances are considered. Velocities and UFP concentrations are collected in a wind tunnel. The influence of the rear slant angle of the leading vehicle is discussed on both wake dynamics and concentration fields. The results indicate that a critical inter-vehicle distance can be identified above which the recirculation region remains unchanged. Considering the concentration fields, for a leading vehicle with φ=0°, the large recirculation region tends to entrap the particles and to homogenize the particle mixing. For φ=25°, the attachment of the flow in the rear slant angle has a strong impact on the particle dispersion. It leads to a small recirculation region, which entraps particles leading to a non-homogeneous mixing. The Particle Concentration fields in Number (PNC) reveal high levels in the exhaust tailpipe plane that can contribute to lower PNC levels in the car cabin. Comparisons with previous studies are discussed and possible recommendations are suggested.

Longitudinal associations between metabolites and long-term exposure to ambient air pollution: Results from the KORA cohort study

BackgroundLong-term exposure to air pollution has been associated with cardiopulmonary diseases, while the underlying mechanisms remain unclear. ObjectivesTo investigate changes in serum metabolites associated with long-term exposure to air pollution and explore the susceptibility characteristics. MethodsWe used data from the German population-based Cooperative Health Research in the Region of Augsburg (KORA) S4 survey (1999–2001) and two follow-up examinations (F4: 2006–08 and FF4: 2013–14). Mass-spectrometry-based targeted metabolomics was used to quantify metabolites among serum samples. Only participants with repeated metabolites measurements were included in the current analysis. Land-use regression (LUR) models were used to estimate annual average concentrations of ultrafine particles, particulate matter (PM) with an aerodynamic diameter less than 10 μm (PM10), coarse particles (PMcoarse), fine particles, PM2.5 absorbance (a proxy of elemental carbon related to traffic exhaust, PM2.5abs), nitrogen oxides (NO2, NOx), and ozone at individuals’ residences. We applied confounder-adjusted mixed-effects regression models to examine the associations between long-term exposure to air pollution and metabolites. ResultsAmong 9,620 observations from 4,261 KORA participants, we included 5,772 (60.0%) observations from 2,583 (60.6%) participants in this analysis. Out of 108 metabolites that passed stringent quality control across three study points in time, we identified nine significant negative associations between phosphatidylcholines (PCs) and ambient pollutants at a Benjamini-Hochberg false discovery rate (FDR) corrected p-value < 0.05. The strongest association was seen for an increase of 0.27 μg/m3 (interquartile range) in PM2.5abs and decreased phosphatidylcholine acyl-alkyl C36:3 (PC ae C36:3) concentrations [percent change in the geometric mean: −2.5% (95% confidence interval: −3.6%, −1.5%)]. ConclusionsOur study suggested that long-term exposure to air pollution is associated with metabolic alterations, particularly in PCs with unsaturated long-chain fatty acids. These findings might provide new insights into potential mechanisms for air pollution-related adverse outcomes.

Intelligent PM 2.5 mass concentration analyzer using deep learning algorithm and improved density measurement chip for high-accuracy airborne particle sensor network

The concentration of ultrafine airborne particles is continuously increasing, and research has shown that it has adverse effects when inhaled into the human body. Accordingly, there is a growing demand for a measurement network utilizing sensors to evaluate an individual's exposure to these airborne particles. However, the current low-cost sensors have the limitation of low accuracy. To solve this, we devised a method to calibrate a low-cost mass concentration sensor accurately in real time. In a previous study, we developed an analyzer that could measure the effective density and nanoparticles that cause the low accuracy of the mass concentration sensor. However, it had a hardware stability problem when used to monitor the outside air for a long period. This has been improved by modifying the shape of the Micro-electromechanical system (MEMS)-based chip integrated with the electrical/inertial analysis technology. Hence, the device can now operate with sufficient stability in the outdoor air. In addition, the retrieval algorithm used to convert the measured current values into the effective density and nanoparticle size distribution was prone to errors. It was modified to a deep learning-based physical parameter conversion algorithm to minimize the errors. Thus, we developed a standalone analyzer that integrates the improved nanoparticle and effective density analyzer, temperature and humidity sensor, and low-cost mass concentration sensor. In addition, we developed a technique to calibrate the mass concentration sensor data accurately in real time based on the data measured by each sensor and analyzer and a deep learning-based mass concentration calibration algorithm. The calibration precision was confirmed through comparative evaluation of the analyzer with the results of a beta attenuation mass monitor. In the future, this analyzer can be utilized to build a sensor network that precisely monitors the mass concentration in a large area through multi-point deployment. Alternatively, it can be used for monitoring the mass concentration in an indoor private space, where it is difficult to place expensive and large equipment.

Assessment of Coarse, Fine, and Ultrafine Particles in S-Bahn Trains and Underground Stations in Stuttgart

The Stuttgart S-Bahn network comprises six subway lines and is used by approximately 425,000 people on a daily basis. In previous studies in other cities, it was found that subways can be a source and collection point of particulate matter (PM), which is detrimental to human health. This study focused on making an initial assessment of the pollution situation inside the trains and on the underground platforms. Real-time measurements were performed with high time-resolution instruments inside the S-Bahn trains, two underground stations, and two outdoor stations in the Stuttgart subway network in November 2019. Firstly, the variation in concentration inside the train as it traveled through the tunnel was investigated, and it was recurrently observed that the pollutant concentration in the train increased while traveling through the tunnel and then decreased when nearing the tunnel exit. Secondly, the measurement location with the highest particulate matter concentrations was determined. The particulate matter concentrations on underground platforms were higher than those on the train and on the outdoor platforms. In addition, the dominant fraction of the particulate matter measured was in the range of ultrafine particles (UFP). Finally, the wind speed and wind direction data were analyzed in conjunction with specific locations along the platforms. From the wind measurement results, it was assumed that the combined airflows led to higher particle resuspension and particulate matter concentrations in these areas. In conclusion, it was determined that subway users were exposed to higher particle concentrations, particularly UFP (10–116 nm), while standing on underground platforms and when traveling through underground tunnels. It was found that the PNCs inside the train wagons as well as PM and BC mass concentrations increase when passing through the tunnel. Additionally, the average number concentration of UFPs on underground platforms was significantly higher than in other locations by factors of around 1.7 to 1.9 for UFPs and 1.6 to 2 for coarse and fine particles.

Environmental risk factors of incident distal sensorimotor polyneuropathy: Results from the prospective population-based KORA F4/FF4 study

Distal sensorimotor polyneuropathy (DSPN) is a common condition in older populations with high prevalence of obesity and type 2 diabetes. We hypothesised that the risk of DSPN is increased by multiple ubiquitous environmental risk factors, particularly in people with obesity. This study was based on 423 individuals aged 62–81 years without DSPN who participated in the population-based Cooperative Health Research in the Region of Augsburg (KORA) F4 survey (2006–2008) in Southern Germany. During 6.5 years of follow-up, 188 participants developed clinical DSPN as assessed by the Michigan Neuropathy Screening Instrument. Environmental exposures, including air temperature, surrounding greenness (assessed with the normalized difference vegetation index [NDVI]), long-term road traffic noise and air pollution, were assessed at participants' residences. The cumulative risk index (CRI) evaluated the joint effects of co-occurring exposures on DSPN risk based on effect estimates from multi-exposure Poisson regression models. The models were adjusted for age, sex, height, waist circumference, smoking, alcohol consumption, physical activity, education and neighbourhood socioeconomic status. In the entire cohort, the co-occurrence of an interquartile range (IQR) decrease in temperature of the warm season and NDVI in a 100-m buffer and of an IQR increase in night-time average traffic noise and in annual average particle number concentration (PNC) was positively associated with incident DSPN (CRI [95 % CI] 1.39 [1.02, 1.91]). Effect estimates for exposure combinations were generally higher in individuals with obesity (CRI 1.34–2.01) than in those without obesity (CRI 0.90–1.33). The four-exposure model showed a twofold increased risk of DSPN among obese (CRI [95 % CI] 2.01 [1.10, 3.67]), but not among non-obese individuals (CRI [95 % CI] 1.18 [0.83, 1.67]). Thus, ubiquitous environmental exposures jointly augment the risk of DSPN in the older population. Lower air temperature in the warm season, less greenness, and higher noise levels and ultrafine particle concentrations identified people with obesity as a particularly vulnerable subgroup.

Hyperlocal variation of nitrogen dioxide, black carbon, and ultrafine particles measured with Google Street View cars in Amsterdam and Copenhagen

Hyperlocal air quality maps are becoming increasingly common, as they provide useful insights into the spatial variation and sources of air pollutants. In this study, we produced several high-resolution concentration maps to assess the spatial differences of three traffic-related pollutants, Nitrogen dioxide (NO2), Black Carbon (BC) and Ultrafine Particles (UFP), in Amsterdam, the Netherlands, and Copenhagen, Denmark. All maps were based on a mixed-effect model approach by using state-of-the-art mobile measurements conducted by Google Street View (GSV) cars, during October 2018 – March 2020, and Land-use Regression (LUR) models based on several land-use and traffic predictor variables.We then explored the concentration ratio between the different normalised pollutants to understand possible contributing sources to the observed hyperlocal variations. The maps developed in this work reflect, (i) expected elevated pollution concentrations along busy roads, and (ii) similar concentration patterns on specific road types, e.g., motorways, for both cities. In the ratio maps, we observed a clear pattern of elevated concentrations of UFP near the airport in both cities, compared to BC and NO2.This is the first study to produce hyperlocal maps for BC and UFP using high-quality mobile measurements. These maps are important for policymakers and health-effect studies, trying to disentangle individual effects of key air pollutants of interest (e.g., UFP).

Ultrafine particles exposure is associated with specific operative procedures in a multi-chair dental clinic

Air quality in dental clinics is critical, especially in light of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic, given that dental professionals and patients are at risk of regular exposure to aerosols and bioaerosols in dental clinics. High levels of ultrafine particles (UFP) may be produced by dental procedures. This study aimed to quantify ultrafine particles (UFP) concentrations in a real multi-chair dental clinic and compare the levels of UFP produced by different dental procedures. The efficiency of a high-volume evacuator (HVE) in reducing the UFP concentrations during dental procedures was also assessed. UFP concentrations were measured both inside and outside of a dental clinic in Shanghai, China during a 12-day period from July to September 2020. Dental activities were recorded during working hours. The mean (±standard deviation) concentrations of indoor and outdoor UFP during the sampling period were 8,209 (±4,407) counts/cm3 and 15,984 (±7,977) counts/cm3, respectively. The indoor UFP concentration was much higher during working hours (10,057 ± 5,725 counts/cm3) than during non-working hours (7,163 ± 2,972 counts/cm3). The UFP concentrations increased significantly during laser periodontal treatment, root canal filling, tooth drilling, and grinding, and were slightly elevated during ultrasonic scaling or tooth extraction by piezo-surgery. The highest UFP concentration (241,136 counts/cm3) was observed during laser periodontal treatment, followed by root canal filling (75,034 counts/cm3), which showed the second highest level. The use of an HVE resulted in lower number concentration of UFP when drilling and grinding teeth with high-speed handpieces, but did not significantly reduce UFP measured during laser periodontal therapy. we found that many dental procedures can generate high concentration of UFP in dental clinics, which may have a great health impact on the dental workers. The use of an HVE may help reduce the exposure to UFP during the use of high-speed handpieces.

High time-resolution measurements of ultrafine and fine woodsmoke aerosol number and surface area concentrations in biomass burning kitchens: A case study in Western Kenya.

Indoor air pollution associated with biomass combustion for cooking remains a significant environmental health challenge in rural regions of sub-Saharan Africa; however, routine monitoring of woodsmoke aerosol concentrations continues to remain sparse. There is a paucity of field data on concentrations of combustion-generated ultrafine particles, which efficiently deposit in the human respiratory system, in such environments. Field measurements of ultrafine and fine woodsmoke aerosol (diameter range: 10-2500 nm) with field-portable diffusion chargers were conducted across nine wood-burning kitchens in Nandi County, Kenya. High time-resolution measurements (1Hz) revealed that indoor particle number (PN) and particle surface area (PSA) concentrations of ultrafine and fine woodsmoke aerosol are strongly temporally variant, reach exceedingly high levels (PN > 106 /cm3 ; PSA > 104 μm2 /cm3 ) that are seldom observed in non-biomass burning environments, are influenced by kitchen architectural features, and are moderately to poorly correlated with carbon monoxide concentrations. In five kitchens, PN concentrations remained above 105 /cm3 for more than half of the day due to frequent cooking episodes. Indoor/outdoor ratios of PN and PSA concentrations were greater than 10 in most kitchens and exceeded 100 in several kitchens. Notably, the use of metal chimneys significantly reduced indoor PN and PSA concentrations.

Triggering of ST-elevation myocardial infarction by ultrafine particles in New York: Changes following Tier 3 vehicle introduction

BackgroundPreviously, we found increased rates of ST-elevation myocardial infarction (STEMI) associated with increased ultrafine particle (UFP; <100 nm) concentrations in the previous few hours in Rochester, New York. Relative rates were higher after air quality policies and a recession reduced pollutant concentrations (2014–2016 versus 2005–2013), suggesting PM composition had changed and the same PM mass concentration had become more toxic. Tier 3 light duty vehicles, which should produce less primary organic aerosols and oxidizable gaseous compounds, likely making PM less toxic, were introduced in 2017. Thus, we hypothesized we would observe a lower relative STEMI rate in 2017–2019 than 2014–2016. MethodsUsing STEMI events treated at the University of Rochester Medical Center (2014–2019), UFP and other pollutants measured in Rochester, a case-crossover design, and conditional logistic regression models, we estimated the rate of STEMI associated with increased UFP and other pollutants in the previous hours and days in the 2014–2016 and 2017–2019 periods. ResultsAn increased rate of STEMI was associated with each 3111 particles/cm3 increase in UFP concentration in the previous hour in 2014–2016 (lag hour 0: OR = 1.22; 95% CI = 1.06, 1.39), but not in 2017–2019 (OR = 0.94; 95% CI = 0.80, 1.10). There were similar patterns for black carbon, UFP11–50nm, and UFP51–100nm. In contrast, increased rates of STEMI were associated with each 0.6 ppb increase in SO2 concentration in the previous 120 h in both periods (2014–2016: OR = 1.26, 95% CI = 1.03, 1.55; 2017–2019: OR = 1.21, 95% CI = 0.87, 1.68). ConclusionsGreater rates of STEMI were associated with short term increases in concentrations of UFP and other motor vehicle related pollutants before Tier 3 introduction (2014–2016), but not afterwards (2017–2019). This change may be due to changes in PM composition after Tier 3 introduction, as well as to increased exposure misclassification and greater underestimation of effects from 2017 to 2019.

Coagulation contributing to electrostatic precipitation of ultrafine fly ash from small-scale biomass combustions

An electrostatic precipitator (ESP) is an efficient device for removing fly ash from small-scale solid-fuel combustion. Under corona discharge, a gaseous medium becomes ionised, and particles become charged by colliding with ions. An electric field forces the movement of charged particles to remove gases and induces the movement of generated ions, causing secondary electrohydrodynamic flow. Thus, particle charge, the presence of neighbouring particles, an ESP electric field, and gas flow turbulence can enhance particle coagulation. Therefore, the ultrafine particle concentration in an ESP is expected to evolve under electrostatic removal and enhanced coagulation. In the present study, the contribution of coagulation is explored and confirmed using experimental measurements performed on an ESP used to control emissions from a 160-kW boiler with biomass combustion. The ESP was operated under several modes to obtain different coagulation conditions. Changes in particle concentrations were measured simultaneously using two techniques. It was found that coagulation could be responsible for up to 5% of the total removal efficiency, depending on the ESP operation parameters. The present study can promote a deeper understanding of the processes involved in electrostatic precipitation, and the obtained results can be useful for practical ESP engineering.