Levels Of Ultrafine Particles Research Articles

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.

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.

Source apportionment of fine and ultrafine particle number concentrations in a major city of the Eastern Mediterranean

Ultrafine particles (UFP) are recognized as an emerging pollutant able to induce serious health effects. However, quantitative information regarding the contributions of UFP sources is generally limited. This study evaluates statistical (k-means clustering) and receptor models (Positive Matrix Factorization - PMF) using particle number size distributions (PNSD), along with chemical speciation data, measured at an urban background supersite in Athens, Greece, aiming to characterize their sources. PNSD measurements (10–487 nm) were performed during three distinct periods (warm, cold, and lockdown cold). Traffic and residential biomass burning (BB) produced high UFP number concentrations (NUFP) in the cold period (+107 % compared to summer), while the lockdown restrictions reduced NUFP (−42 %). The five groups produced by cluster analysis that were common among periods were linked to high- and low-traffic, new particle formation (NPF), urban background and regional aerosols. PMF source apportionment identified 5 and 6 factors during warm and cold periods, respectively, indicating that traffic particles dominated NUFP (64–78 % in all periods), while accumulation-mode particles and volume concentrations were controlled by processed aerosol, and especially in the cold periods by BB emissions. A nucleation factor linked to NPF contributed 7–11 % to NUFP. Comparing the two cold periods (business-as-usual, lockdown), important lockdown reductions (−46 %) were seen for fresh traffic contributions to total number concentration (Ntotal). The impact of the source attributed to NPF also eroded (−41 % for Ntotal). Due to the large reduction (−47 % for Ntotal) observed also for the BB source during the lockdown (reduced wood usage due to a milder winter), the relative contributions of all sources did not change considerably (fractional reductions <7 % for Ntotal). The quantitative results, bolstered by source apportionment combining PNSD and online chemical composition measurements, indicate the potential to constrain UFP levels by regulating traffic and residential emissions, with a large upside for population exposure control.

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.

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.

The impact of COVID-19 lockdown restrictions on the short-term association between in-vehicle particulate pollutants and the respiratory health of Parisian taxi drivers.

This study assessed the short-term associations between in-vehicle ultrafine particles (UFP) and black carbon (BC) concentrations and irritation symptoms and lung parameters of taxi drivers, pre- and post-lockdown. As part of PUF-TAXI project, 33 taxi drivers were followed up during two typical working days. In-vehicle UFP and BC were continuously measured by monitoring instruments. Irritation symptoms during the working day were reported via an auto-questionnaire and lung function was assessed by a portable spirometer, pre- and post- work shift. Generalized estimating equations, adjusted for potential confounders, were used to study the association between air pollutants and health outcomes. Effect modification by measurement period (pre- and post-lockdown) was investigated. UFP and BC concentrations inside taxi vehicles decreased significantly post- compared to pre-lockdown. Incidence of nose irritation was positively associated with in-vehicle UFP and BC levels pre-lockdown, when pollutant levels were higher, whereas no significant association was found post-lockdown. The decrease in the FEF25-75% (forced expiratory flow at 25-75% of the forced vital capacity) during the working day was significantly associated with in-taxi UFP levels before but not after lockdown. No association was found with BC. By contrast, incidence of eye irritation was significantly inversely associated with in-vehicle humidity, regardless of pollutant concentrations and the measurement period. Our findings indicate that an upgrade in in-vehicle air quality could improve respiratory health. This study showed that the magnitude of the incidence of nasal irritation and decrease in lung function depends on UFP concentrations the commuters are exposed to.

A hybrid model for estimating the number concentration of ultrafine particles based on machine learning algorithms in central Taiwan

Modeling is a cost-effective measure to estimate ultrafine particle (UFP) levels. Previous UFP estimates generally relied on land-use regression with insufficient temporal resolution. We carried out in-situ measurements for UFP in central Taiwan and developed a model incorporating satellite-based measurements, meteorological variables, and land-use data to estimate daily UFP levels at a 1-km resolution. Two sampling campaigns were conducted for measuring hourly UFP concentrations at six sites between 2008–2010 and 2017–2021, respectively, using scanning mobility particle sizers. Three machine learning algorithms, namely random forest, eXtreme gradient boosting (XGBoost), and deep neural network, were used to develop UFP estimation models. The performances were evaluated with a 10-fold cross-validation, temporal, and spatial validation. A total of 1,022 effective sampling days were conducted. The XGBoost model had the best performance with a training coefficient of determination (R2) of 0.99 [normalized root mean square error (nRMSE): 6.52%] and a cross-validation R2 of 0.78 (nRMSE: 31.0%). The ten most important variables were surface pressure, distance to the nearest road, temperature, calendar year, day of the year, NO2, meridional wind, the total length of roads, PM2.5, and zonal wind. The UFP levels were elevated along the main roads across different seasons, suggesting that traffic emission is an important contributor to UFP. This hybrid model outperformed prior land use regression models and thus can provide more accurate estimates of UFP for epidemiological studies.

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.

Metal compositions of particle emissions from material extrusion 3D printing: Emission sources and indoor exposure modeling

Material extrusion 3D printing has been widely used in industrial, educational and residential environments, while its exposure health impacts have not been well understood. High levels of ultrafine particles are found being emitted from 3D printing and could pose a hazard when inhaled. However, metals that potentially transfer from filament additives to emitted particles could also add to the exposure hazard, which have not been well characterized for their emissions. This study analyzed metal (and metalloid) compositions of raw filaments and in the emitted particles during printing; studied filaments included pure polymer filaments with metal additives and composite filaments with and without metal powder. Our chamber study found that crustal metals tended to have higher partitioning factors from filaments to emitted particles; silicon was the most abundant element in emitted particles and had the highest yield per filament mass. However, bronze and stainless-steel powder added in composite filaments were less likely to transfer from filament to particle. For some cases, boron, arsenic, manganese, and lead were only detected in particles, which indicated external sources, such as the printers themselves. Heavy metals with health concerns were also detected in emitted particles, while their estimated exposure concentrations in indoor air were below air quality standards and occupational regulations. However, total particle exposure concentrations estimated for indoor environments could exceed ambient air fine particulate standards.

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.

Unprecedented levels of ultrafine particles, major sources, and the hydrological cycle

Ultrafine particles (UFP) acting as cloud condensation nuclei (CCN) are the driving force behind changing rainfall patterns. Recently observed weather extremes like floods and drought might be due to changing anthropogenic UFP emissions. However, the sources and budgets of anthropogenic primary and secondary particles are not well known. Based on airborne measurements we identified as a major contribution modern fossil fuel flue gas cleaning techniques to cause a doubling of global primary UFP number emissions. The subsequent enhancement of CCN numbers has several side effects. It’s changing the size of the cloud droplets and delays raindrop formation, suppressing certain types of rainfall and increasing the residence time of water vapour in the atmosphere. This additional latent energy reservoir is directly available for invigoration of rainfall extremes. Additionally it’s a further contribution to the column density of water vapour as a greenhouse gas and important for the infrared radiation budget. The localized but ubiquitous fossil fuel related UFP emissions and their role in the hydrological cycle, may thus contribute to regional or continental climate trends, such as increasing drought and flooding, observed within recent decades.

Volatile organic compound and particulate emissions from the production and use of thermoplastic biocomposite 3D printing filaments

Biocomposites (BCs) can be used as substitutes for unsustainable polymers in 3D printing, but their safety demands additional investigation as biological fillers may produce altered emissions during thermal processing. Commercial filament extruders can be used to produce custom feedstocks, but they are another source of airborne contaminants and demand further research. These knowledge gaps are targeted in this study. Volatile organic compound (VOC), carbonyl compound, ultrafine particle (UFP), and fine (PM2.5) and coarse (PM10) particle air concentrations were measured in this study as a filament extruder and a 3D printer were operated under an office environment using one PLA and four PLA-based BC feedstocks. Estimates of emission rates (ERs) for total VOCs (TVOC) and UFPs were also calculated. VOCs were analyzed with a GC-MS system, carbonyls were analyzed with an LC-MS/MS system, whereas real-time particle concentrations were monitored with continuously operating instruments. VOC concentrations were low throughout the experiment; TVOC ranged between 34–63 µg/m3 during filament extrusion and 41–56 µg/m3 during 3D printing, which represent calculated TVOC ERs of 2.6‒3.6 × 102 and 2.9‒3.6 × 102 µg/min. Corresponding cumulative carbonyls ranged between 60–91 and 190–253 µg/m3. Lactide and miscellaneous acids and alcohols were the dominant VOCs, while acetone, 2-butanone, and formaldehyde were the dominant carbonyls. Terpenes contributed for ca. 20–40% of TVOC during BC processing. The average UFP levels produced by the filament extruder were 0.85 × 102–1.05 × 103 #/cm3, while the 3D printer generated 6.05 × 102–2.09 × 103 #/cm3 particle levels. Corresponding particle ERs were 5.3 × 108–6.6 × 109 and 3.8 × 109–1.3 × 1010 #/min. PM2.5 and PM10 particles were produced in the following average quantities; PM2.5 levels ranged between 0.2–2.2 µg/m3, while PM10 levels were between 5–20 µg/m3 for all materials. The main difference between the pure PLA and BC feedstock emissions was terpenes, present during all BC extrusion processes. BCs are similar emission sources as pure plastics based on our findings, and a filament extruder produces contaminants at comparable or slightly lower levels in comparison to 3D printers.

Identifying trends in ultrafine particle infiltration and carbon dioxide ventilation in 92 vehicle models

There has been ongoing research aimed at reducing pollution concentrations in vehicles due to the high exposure which occurs in this setting. These studies have found using recirculate (RC) settings substantially reduces in-cabin traffic-related pollution concentrations but possibly leads to an adverse accumulation of carbon dioxide (CO2) from driver respiration. The aim of this study was to highlight how vehicle models and ventilation settings affect in-cabin concentrations to ultrafine particles (UFP) and CO2 in real-world conditions. We assessed the ability of different vehicles to balance reductions in UFP against the build-up of in-cabin CO2 concentrations by measuring these pollutants concurrently both inside and outside the vehicle to derive an in/out ratio.When ventilation settings were set to RC, UFP concentrations inside the vehicles (median: 3205 pt./cm3) were 86% lower compared to outside air (OA) (23,496 pt./cm3) across a 30-min real-world driving route. However, CO2 concentrations demonstrated a rapid linear increase under RC settings, at times exceeding 2500 ppm. These concentrations have previously been associated with decreased cognitive performance. Our study did not find an effect of gasoline fuelled vehicles affecting in-cabin UFP levels compared to hybrid or electric vehicles, suggesting that self-pollution was not an issue. We also found that certain vehicle models were better at reducing both in-cabin UFP and CO2 concentrations. The results suggest that under RC settings in/out CO2 ratios are largely determined by the leakiness of the vehicle cabin, whereas in/out UFP ratios are primarily determined by the efficacy of the in-built air filter in the vehicles ventilation system.

A new exposure metric for the cumulative effect of short-term exposure peaks of traffic-related ultrafine particles.

The adverse health outcomes of traffic-related ultrafine particles (UFPs) disproportionally impact near-highway neighborhoods. Current studies focus on either short-term health outcomes associated with short-term UFP exposures averaged over days or weeks, or long-term outcomes associated with long-term (yearly or longer) average UFP exposures. We hypothesized that frequent and repeated exposure to short-term UFP peaks that last for just hours could overwhelm or alter physiological defensive responses, resulting in long-term health issues. Herein, we propose a new exposure metric for measuring the cumulative effect of these peak exposures. We used UFP exposure data estimated by the Community Assessment of Freeway Exposure and Health (CAFEH) project, which recruited 704 participants from three pairs of near-highway/urban background neighborhoods in the Greater Boston Area between 2009 and 2012. CAFEH developed land use regression (LUR) models to estimate hourly averages of ambient UFP levels within the study areas based on mobile-monitored UFP data, and applied time-activity adjustment (TAA) to calculate adjusted final hourly estimates. Our alternative metric assigns cumulative peak exposure, which is determined as either the intensity (a high percentile of an individual's adjusted hourly UFP estimates) or the frequency (the number of hours with adjusted UFP estimates greater than a high percentile of all adjusted hourly UFP estimates of all participants in the study area) of UFP peaks. After TAA was applied, for most of the time, our cumulative peak exposure metrics were not strongly correlated with the annual average. However, the level of correlation varied greatly from neighborhood to neighborhood (Spearman's R ranges from 0.39 to 0.97). There was variation in UFP peak exposure that was not explained by the annual average, suggesting that our proposed peak metric distinct from annual average exposure metric.

Hyperlocalized Measures of Air Pollution and Preeclampsia in Oakland, California.

Exposure to nitrogen dioxide (NO2), black carbon (BC), and ultrafine particles (UFPs) during pregnancy may increase the risk of preeclampsia, but previous studies have not assessed hyperlocalized differences in pollutant levels, which may cause exposure misclassification. We used data from Google Street View cars with mobile air monitors that repeatedly sampled NO2, BC, and UFPs every 30 m in Downtown and West Oakland neighborhoods during 2015-2017. Data were linked to electronic health records of pregnant women in the 2014-2016 Sutter Health population, who resided within 120 m of monitoring data (N = 1095), to identify preeclampsia cases. We used G-computation with log-binomial regression to estimate risk differences (RDs) associated with a hypothetical intervention reducing pollutant levels to the 25th percentile observed in our sample on preeclampsia risk, overall and stratified by race/ethnicity. Prevalence of preeclampsia was 6.8%. Median (interquartile range) levels of NO2, BC, and UFPs were 10.8 ppb (9.0, 13.0), 0.34 μg/m3 (0.27, 0.42), and 29.2 # × 103/cm3 (26.6, 32.6), respectively. Changes in the risk of preeclampsia achievable by limiting each pollutant to the 25th percentile were NO2 RD = -1.5 per 100 women (95% confidence interval (CI): -2.5, -0.5); BC RD = -1.0 (95% CI: -2.2, 0.02); and UFP RD = -0.5 (95% CI: -1.8, 0.7). Estimated effects were the largest for non-Latina Black mothers: NO2 RD = -2.8 (95% CI: -5.2, -0.3) and BC RD = -3.0 (95% CI: -6.4, 0.4).

Dynamic molecular choreography induced by traffic exposure: A randomized, crossover trial using multi-omics profiling

The biological mechanism of adverse health outcomes related to exposure to traffic-related air pollution (TRAP) needs elucidation. We conducted a randomized, crossover trial among healthy young students in Shanghai, China. Participants wore earplugs and were randomly assigned to a 4-hour walking treatment either along a traffic-polluted road or through a traffic-free park. We conducted untargeted analyses of plasma exosome transcriptomics, serum mass spectrometry-based proteomics, and serum metabolomics to evaluate changes in genome-wide transcription, protein, and metabolite profiles in 35 randomly selected participants. Mean personal exposure levels of ultrafine particles, black carbon, nitrogen dioxide, and carbon monoxide in the road were 2–3 times higher than that in the park. We observed 3449 exosome mRNAs, 58 serum proteins, and 128 serum metabolites that were significantly associated with TRAP. The multi-omics analysis showed dozens of regulatory pathways altered in response to TRAP, such as inflammation, oxidative stress, coagulation, endothelin-1 signaling, and renin-angiotensin signaling. We found that several novel pathways activated in response to TRAP exposure: growth hormone signaling, adrenomedullin signaling, and arachidonic acid metabolism. Our study served as a demonstration and proof of concept on the evidence that associated TRAP exposure with global molecular changes based on the multi-omics level.

Ultrafine particles in key microenvironments in rural and urban areas of Ghana

Urban air pollution presents significant health risks to urban dwellers around the world. Knowledge of the levels of air pollution at various spatial locations in a city, offers insight into the personal exposure of residents and facilitates the control of air pollution. This study investigated ultrafine particles (UFP) in key microenvironments in which people spend a significant amount of their time in three suburbs of Accra (the capital city of Ghana) and in a nearby rural community (Berekuso). The ambient concentrations of UFP across the study area were also mapped. The median daily ambient UFP concentration at a reference site at Kwabenya, a suburb of Accra, was 5.8(IQR:1.6−17.1)×104cm−3. The UFP on the reference site were mainly influenced by vehicular traffic, and open-air burning in communities near the site, and by extention, wind direction. The mean (±SEM) UFP concentrations reported in five school and household microenvironments in two suburbs in Accra (Madina and Agbogbloshie) and in Berekuso ranged between 9.1×103(±7.3×102) and 1.5×105(±1.9×104)cm−3. The microenvironmental concentrations were mainly influenced by lifestyle and sociocultural factors. The results highlight the high levels of UFP in many of the microenvironments investigated, the potential health risks that UFP pose to sensitive groups, and the overall urgency for the control of air pollution in Accra.

Occupational exposure and markers of genetic damage, systemic inflammation and lung function: a Danish cross-sectional study among air force personnel

Air force ground crew personnel are potentially exposed to fuels and lubricants, as raw materials, vapours and combustion exhaust emissions, during operation and maintenance of aircrafts. This study investigated exposure levels and biomarkers of effects for employees at a Danish air force military base. We enrolled self-reported healthy and non-smoking employees (n = 79) and grouped them by exposure based on job function, considered to be potentially exposed (aircraft engineers, crew chiefs, fuel operators and munition specialists) or as reference group with minimal occupational exposure (avionics and office workers). We measured exposure levels to polycyclic aromatic hydrocarbons (PAHs) and organophosphate esters (OPEs) by silicone bands and skin wipes (PAHs only) as well as urinary excretion of PAH metabolites (OH-PAHs). Additionally, we assessed exposure levels of ultrafine particles (UFPs) in the breathing zone for specific job functions. As biomarkers of effect, we assessed lung function, plasma levels of acute phase inflammatory markers, and genetic damage levels in peripheral blood cells. Exposure levels of total PAHs, OPEs and OH-PAHs did not differ between exposure groups or job functions, with low correlations between PAHs in different matrices. Among the measured job functions, the UFP levels were higher for the crew chiefs. The exposure level of the PAH fluorene was significantly higher for the exposed group than the reference group (15.9 ± 23.7 ng/g per 24 h vs 5.28 ± 7.87 ng/g per 24 h, p = 0.007), as was the OPE triphenyl phosphate (305 ± 606 vs 19.7 ± 33.8 ng/g per 24 h, p = 0.011). The OPE tris(1,3-dichlor-2-propyl)phosphate had a higher mean in the exposed group (60.7 ± 135 ng/g per 24 h) compared to the reference group (8.89 ± 15.7 ng/g per 24 h) but did not reach significance. No evidence of effects for biomarkers of systemic inflammation, genetic damage or lung function was found. Overall, our biomonitoring study show limited evidence of occupational exposure of air force ground crew personnel to UFPs, PAHs and OPEs. Furthermore, the OH-PAHs and the assessed biomarkers of early biological effects did not differ between exposed and reference groups.

Ultrafine particle levels measured on board short-haul commercial passenger jet aircraft

BackgroundAirline crew members report adverse health effects during and after inhalation exposure to engine oil fumes sourced to the air supply system onboard commercial and military aircraft. Most investigations into the causal factors of their reported symptoms focus on specific chemical contaminants in the fumes. The adverse health effects reported in aircrew exposed to the aircraft air supply, bled unfiltered off the engine or Auxiliary Power Unit (APU) may be related to particulate exposures, which are widely known to effect health. While oil contaminates the aircraft air supply, some suggest that this will only occur when there is a bearing seal failure, others document that there is low level oil contamination of the air supply during normal engine operation. This brief pilot study explores whether particulate exposure may be associated with the normal engine/APU and air supply operation and to therefore increase the understanding that UFP exposures may have on crew and passengers.MethodsAn ultrafine particle counter was utilised by an experienced airline captain in the passenger cabin of four short-haul commercial passenger aircraft. All flights were under 90 min on aircraft from two different carriers ranging from 7 months to 14 years old.ResultsUFP concentrations showed maximum concentrations ranging from 31,300 to 97,800 particles/cm3 when APU was selected on as a source of air on the ground and with engine bleed air and the air conditioning packs selected on during the climb. In 2 of the 4 flights the peaks were associated with an engine oil smell. Increases in UFP particle concentrations occurred with changes in engine/APU power and air supply configuration changes.ConclusionsThis study identified increases in UFP concentrations associated with engine and APU power changes and changes in air supply configuration. These results correlated with times when engine and APU oil seals are known to be less effective, enabling oil leakage to occur. The concentrations reached in the passenger cabins exceeded those taken in other ground-based environments. UFP exposures in aircraft cabins during normal flight indicates there will be health consequences for long serving aircrew and some passengers.

Characteristics and risk assessment of occupational exposure to ultrafine particles generated from cooking in the Chinese restaurant

Ultrafine particles have been increasingly linked to adverse health effects in restaurant workers. This study aimed to clarify the exposure characteristics and risks of ultrafine particles during the cooking process, and to provide a reasonable standard for protecting the workers in the Chinese restaurant. The temporal variations in particle concentrations (number concentration (NC), mass concentration (MC), surface area concentration (SAC), and personal NC), and size distributions by number were measured by real-time system. The hazard, exposure, and risk levels of ultrafine particles were analyzed using the control banding tools. The NC, MC, and SAC increased during the cooking period and decreased gradually to background levels post-operation. The concentration ratios of MC, total NC, SAC, and personal NC ranged from 3.82 to 9.35. The ultrafine particles were mainly gathered at 10.4 and 100 nm during cooking. The exposure, hazard and risk levels of the ultrafine particles were high. These findings indicated that the workers during cooking were at high risk due to exposure to high levels of ultrafine particles associated with working activity and with a bimodal size distribution. The existing control strategies, including engineering control, management control, and personal protection equipment need to be improved to reduce the risk.