Ultrafine Particle Concentrations Research Articles

Exposure to ultrafine particles and black carbon at schools near a large Dutch Airport

TPS 761: Health effects of pollution sources and components, Johan Friso Foyer, Floor 1, August 28, 2019, 3:00 PM - 4:30 PM Background: Recent studies have shown elevated concentrations of ultrafine particles (UFP) near airports. Aircraft emissions are characterized by a smaller particle size and relatively low levels of Black Carbon (BC) compared to other combustion sources, such as road traffic. We measured particle number concentrations (PNC), particle size distribution and BC simultaneously outside 2 schools near Schiphol Airport. Methods: We conducted continuous measurements of PNC (Scanning Mobility Particle Sizer; GRIMM-5420/L-DMA) and BC (MAAP; Thermo-5012) outside 2 schools simultaneously for 1 year (December 2017-december 2018). One school was located south of the airport and the other school North-Northeast of the airport. Schools were located at approximately 8 km distance from each other and at 2-3 km distance from the nearest runway. We analyzed hourly average concentrations of total and size-specific PNC and BC in relation to wind direction, as well as correlations between and within schools. Results: We observed 2-3 times higher total PNC levels when the schools were downwind of the airport. This elevation was most pronounced for PNC<30nm (4-fold increase) and decreased with increasing particle size. Correlations between schools were low for PNC (R 0.07) and high for BC (R 0.86). Within schools, BC was poorly correlated withtotal PNC and PNC<30nm (R 0.17-0.33). Correlations with BC increased with increasing particles size (R 0.61-0.66 for PNC>30nm and 0.75-0.77 for PNC>50nm). Conclusions: We found elevated levels of airport related PNC at schools near Schiphol airport. Variations in airport related PNC were largely independent of variations in BC. Results will be used in a panel study on short-term effects of UFP on schoolchildren

A Nationwide Land Use Regression Model for Ultrafine Particles

TPS 651: Air pollution exposure modeling 1, Exhibition Hall, Ground floor, August 27, 2019, 3:00 PM - 4:30 PM Background: Ultrafine Particles (UFP) are highly variable in space and time and are therefore difficult to predict on a large scale. Previous modelling studies have been published for single metropolitan areas. National models have not been developed which limits exposure for nationwide cohorts. Objectives: The aim of the paper is to create nationwide Land Use Regression (LUR) Model for UFP to be used in epidemiological studies. Method: We used a mobile platform to sample UFP concentrations across the Netherlands for a period of 16 months (2016-2017), with a total of 14.392 road segments sampled 3 times on average. Average concentrations per road segment (~43 seconds of data) and extracted GIS variables were used to develop LUR models using a supervised forward regression approach, as well as a deconvolution, LASSO and random forest algorithm. The deconvolution approach develops separate models for regional, urban and local scales. All models were tested on longer-term UFP measurements in 2014 at 42 sites with an average of 3 times 24 hours of measurements. Results: Out of the four prediction models, the LASSO model predicted the longer-term UFP measurements best (R2 =0.68). The supervised LUR model, deconvoluted approach and random forest algorithm predicted 51%, 62% and 56% of the variation in the longer-term UFP measurements respectively. Conclusions: We were able to develop nationwide models for UFP with good performance. The models will be applied in nationwide epidemiological studies. More modelling sophisticated procedures improved predictive power. The deconvoluted approach improved the standard linear model by distinguishing separate spatial scales.

Modelling of long-term average aviation-related ultrafine particle concentrations for use in epidemiological studies

Modelling of long-term average aviation-related ultrafine particle concentrations for use in epidemiological studies

The utility of local smoke evacuation in reducing surgical smoke exposure in spine surgery: a prospective self-controlled study

BACKGROUND CONTEXTExposure to surgical smoke remains a potential occupational health concern to spine operating room personnel. Using a smoke evacuator (local exhaust ventilation) is currently regarded as a primary means of protection, yet few studies have evaluated its utility in actual surgeries. OBJECTIVETo examine the utility of two common types of local smoke evacuators, a para incisional evacuator and a smoke evacuation pencil, in reducing surgical smoke exposure in spine surgery. STUDY DESIGNA prospective self-controlled study. PATIENT SAMPLEAfter the pre-estimation of sample size, 51 consecutive spine surgeries (25 and 26 patients using the para incisional smoke evacuator and the smoke evacuation pencil, respectively) were enrolled between February 2018 and March 2019. OUTCOME MEASURESTwo outcome measures were used to evaluate the level of surgical smoke exposure, which was defined as the concentration of ultrafine smoke particles in the air (number of particles per cm3, ppc) around the operating table: (a) the average smoke level was the arithmetic mean of all measurements recorded during the surgery; and (b) the peak smoke level was the highest measurement recorded. METHODSConsecutive surgeries that involved bilateral symmetrical surgical exposure of the spine via a posterior midline incision were evaluated. Cauterized smoke was evacuated by two smoke evacuators: a “para incisional evacuator,” which used a flat broad suction pad positioned immediately adjacent to the incision (25 patients), and a “surgical smoke evacuation pencil” which is an incorporated part of the electrocautery (26 patients). The level of smoke exposure was measured separately when surgically exposing the two sides of the spine: starting with one side (determined randomly) with the smoke evacuator being turned on and, then, the other side with the smoke evacuator off. The results were compared between the two sides. RESULTSThe para incisional smoke evacuator significantly reduced the average smoke level by an average of 59.7% (287 [interquartile range {IQR}: 126, 526] vs. 1,177 [IQR: 395, 2,702], p<.001). The surgical smoke evacuation pencil also reduced the average smoke level by an average of 44.1% (917 [IQR: 448, 1936] vs. 1,605 [IQR: 775, 4,280], p<.001). Both evacuators significantly reduced peak smoke levels as well. CONCLUSIONSThis study provides evidence supporting the utility of local smoke evacuation in reducing surgical smoke exposure in spine surgery. Such technology may help to improve the occupational health protection for spine operating room workers.

Characteristics of school children's personal exposure to ultrafine particles in Heshan, Pearl River Delta, China – A pilot study

BackgroundThere is a significant lack of scientific knowledge on population exposure to ultrafine particles (UFP) in China to date. This paper quantifies and characterises school children's personal UFP exposure and exposure intensity against their indoor and outdoor activities during a school day (home, school and commuting) in the city of Heshan within the Pearl River Delta (PRD) region, southern China. MethodsTime-series of UFP number concentrations and average size were measured over 24 h for 24 children (9–13 years old), using personal monitors over two weeks in April 2016. Time-activity diaries and a questionnaire on the general home environment and potential sources of particles at home were also collected for each participating child. The analysis included concurrently measured size distributions of ambient UFP at a nearby fixed reference site (Heshan Supersite). ResultsHourly average UFP concentrations exhibited three peaks in the morning, midday and evening. Time spent indoors at home was found to have the highest average exposure (1.26 × 104 cm−3 during sleeping) and exposure intensity (2.41). While there is always infiltration of outdoor particles indoors (from nearby traffic and general urban background sources), indoor exposure at home was significantly higher than outdoor exposure. Based on the collected questionnaire data, this was considered to be driven predominantly by adults smoking and the use of mosquito repellent incense during the night. Outdoor activities at school were associated with the lowest average exposure (6.87 × 102 cm−3) and exposure intensity (0.52). ConclusionDespite the small sample size, this study characterised, for the first time, children's personal UFP exposure in a city downwind of major pollution sources of the PRD region in China. Particularly, the results highlighted the impact of smoking at home on children's exposure. While the study could not apportion the specific contributions of second hand-smoking and mosquito coil burning, considering the prevalence of smokers among the parents who smoke at home, smoking is a very significant factor. Exposure to second-hand smoke is avoidable, and these findings point out to the crucial role of government authorities and public health educators in engaging with the community on the role of air quality on health, and the severity of the impact of second-hand smoke on children's health.

Investigation on combustion and emission characteristics of diesel and gasoline blends with exhaust gas recirculation

ABSTRACTBlending gasoline in diesel may decrease the viscosity and decrease the distillation temperature and thus improve the spray and air-fuel mixture quality. Diesel (D100), 80% diesel and 20% gasoline by vol. (D80G20), and 60% diesel and 40% gasoline by vol. (D60G40) were experimentally investigated. The ignition delay prolongs, the combustion duration shortens and the peak combustion temperature increase with gasoline. The number concentrations (NCs) of ultrafine particles (UFPs) decrease and the NOx emissions increase with gasoline. The NCs of UFPs increase and the NOx emissions decrease with exhaust gas recirculation (EGR). The NCs of UFPs and the NOX emissions of D60G40 can be simultaneously reduced with 20% EGR compared to D100 without EGR.

Indoor measurements of air pollutants in residential houses in urban and suburban areas: Indoor versus ambient concentrations.

Indoor exposure to air pollutants was assessed through 99 visits to 51 homes located in downtown high-rise buildings and detached houses in suburban and rural areas. The ambient concentrations of ultrafine particles (UFP), black carbon (BC), particulate matter smaller than 2.5 μm in diameter (PM2.5), and trace elements were concurrently measured at a central monitoring site in downtown Toronto. Median hourly indoor concentrations for all measurements were 4700 particles/cm3 for UFP, 270 ng/m3 for BC, and 4 μg/m3 for PM2.5, which were lower than ambient outdoor levels by a factor of 2-3. Much higher variability was observed for indoor UFP and BC across the homes compared to ambient levels, mostly due to the influence of indoor cooking emissions. Traffic emissions appeared to have a strong influence on the indoor background (i.e., outdoor-originated) concentrations of BC, UFP, and some trace elements. Specifically, 85% and 34% of the indoor concentrations of BC and UFP were predominantly from outdoor sources, respectively. Moreover, a positive correlation was observed between indoor concentrations of BC and UFP and total road length within a 300 m buffer zone. There was no significant decrease in indoor air pollution with increasing floor level among high-rise residences. In addition to the influence of outdoor sources on indoor air quality, indoor sources contributed to elevated concentrations of K, Ca, Cr, and Cu. A factor analysis was performed on trace elements, UFP, and BC in homes to further resolve possible sources. Local traffic emissions, soil dust, biomass burning, and regional coal combustion were identified as outdoor-originated sources, while cooking emissions was a dominant indoor source. This study highlights how outdoor sources can contribute to chronic exposure in indoor environments and how indoor activities can be associated with acute exposure to temporally varying indoor-originated air pollutants.

Spatial variations in ambient ultrafine particle concentrations and risk of congenital heart defects

BackgroundCardiovascular malformations account for nearly one-third of all congenital anomalies, making these the most common type of birth defects. Little is known regarding the influence of ambient ultrafine particles (<0.1 μm) (UFPs) on their occurrence. ObjectiveThis population-based study examined the association between prenatal exposure to UFPs and congenital heart defects (CHDs). MethodsA total of 158,743 singleton live births occurring in the City of Toronto, Canada between April 1st 2006 and March 31st 2012 were identified from a birth registry. Associations between exposure to ambient UFPs between the 2nd and 8th week post conception when the foetal heart begins to form and CHDs identified at birth were estimated using random-effects logistic regression models, adjusting for personal- and neighbourhood-level covariates. We also investigated multi-pollutant models accounting for co-exposures to PM2.5, NO2 and O3. ResultsA total of 1468 CHDs were identified. In fully adjusted models, UFP exposures during weeks 2 to 8 of pregnancy were not associated with overall CHDs (Odds Ratio (OR) per interquartile (IQR) increase = 1.02, 95% CI: 0.96–1.08). When investigating subtypes of CHDs, UFP exposures were associated with ventricular septal defects (Odds Ratio (OR) per interquartile (IQR) increase = 1.13, 95% CI: 1.03–1.33), but not with atrial septal defect (Odds Ratio (OR) per interquartile (IQR) increase = 0.89, 95% CI: 0.74–1.06). ConclusionThis is the first study to evaluate the association between prenatal exposure to UFPs and the risk of CHDs. UFP exposures during a critical period of embryogenesis were associated with an increased risk of ventricular septal defect.

Health effects of exposure to diesel exhaust in diesel-powered trains

BackgroundShort-term controlled exposure to diesel exhaust (DE) in chamber studies have shown mixed results on lung and systemic effects. There is a paucity of studies on well-characterized real-life DE exposure in humans. In the present study, 29 healthy volunteers were exposed to DE while sitting as passengers in diesel-powered trains. Exposure in electric trains was used as control scenario. Each train scenario consisted of three consecutive days (6 h/day) ending with biomarker samplings.ResultsCombustion-derived air pollutants were considerably higher in the passenger carriages of diesel trains compared with electric trains. The concentrations of black carbon and ultrafine particles were 8.5 μg/m3 and 1.2–1.8 × 105 particles/cm3 higher, respectively, in diesel as compared to electric trains. Net increases of NOx and NO2 concentrations were 317 μg/m3 and 36 μg/m3. Exposure to DE was associated with reduced lung function and increased levels of DNA strand breaks in peripheral blood mononuclear cells (PBMCs), whereas there were unaltered levels of oxidatively damaged DNA, soluble cell adhesion molecules, acute phase proteins in blood and urinary excretion of metabolites of polycyclic aromatic hydrocarbons. Also the microvascular function was unaltered. An increase in the low frequency of heart rate variability measures was observed, whereas time-domain measures were unaltered.ConclusionExposure to DE inside diesel-powered trains for 3 days was associated with reduced lung function and systemic effects in terms of altered heart rate variability and increased levels of DNA strand breaks in PBMCs compared with electric trains.Trial registrationClinicalTrials.Gov (NCT03104387). Registered on March 23rd 2017

Urban Ultrafine Particle Exposure Assessment with Land-Use Regression: Influence of Sampling Strategy.

Sampling strategies in the collection of ultrafine particle (UFP) data to develop land-use regression (LUR) models can strongly influence the resulting exposure estimates. Here, we systematically examine how much sampling is needed to develop robust and stable UFP LUR models. To address this question, we collected 3-6 weeks of continuous measurements of UFP concentrations at 32 sites in Pittsburgh, Pennsylvania covering a wide range of urban land-use attributes. Through systematic subsampling of this data set, we evaluate the performance of hundreds of LUR models with varying numbers of sampling days and daily sampling durations. Our base LUR model derived from wintertime average concentrations explained about 80% of the spatial variability in the data (adjusted R2 ∼ 0.8). The performance of the LUR models degrades with decreasing number of sampling days and sampling duration per day. For our data set, 1-3 h of sampling per day for 10-15 days provided UFP concentration estimates comparable to models derived from the entire data set. Small numbers of repeated sampling per site (1-3 days) at short duration (∼15-60 min per day) result in poor performance ( R2 < 0.5), similar to previous UFP LUR models. This study provides guidelines for the design of future measurement campaigns and monitoring networks to generate robust UFP LUR models for exposure assessments. Further study in other locations with more sites is needed to evaluate these guidelines over a broader range of conditions.

The contribution of moped emissions to ultrafine and fine particle concentrations on bike lanes

Although not emitting air pollution themselves, cyclists are exposed to air pollution from motorised traffic. Because of the close proximity of mopeds to cyclists, moped emissions may affect cyclist exposure. However, the quantitative contribution of mopeds to cyclists' air pollution exposures is uncertain. The aim of the research was to quantify the contribution of moped emissions to air pollution concentrations on bike lanes.Measurements of Particle Number Concentrations (PNC),11PNC = Particle Number Count Particulate Matter (PM)22PM = Particulate Matter and Black Carbon (BC)33BC = Black Carbon on bike lanes were performed in September 2016 in four Dutch cities. Passing two- and four-stroke mopeds and other traffic were recorded and distinguished by sound by the trained field worker. One-second PNC, PM and one-minute BC concentrations were measured. Using regression analyses the contribution of passing mopeds to air pollution exposure was analysed.At 18 non-tunnel locations, two-stroke and four-stroke mopeds contributed at average 12,000 and 3000 pt./cm3 PNC per second when passing by, respectively. In a tunnel, this was 92,000 and 12,000 pt./cm3. Two- and four-strokes added 3 to 19% to total PNC at non-tunnel sites and 58% in a tunnel. Four-strokes caused at average 54% of the contribution of moped emissions to total PNC. At non-tunnel sites, the contribution of mopeds to PM was 1.2 and 0.2 μg/m3 for two- and four-strokes, respectively. In a tunnel this was 3.9 and 2.3 μg/m3. Minute-measurements of BC did not show a relation between mopeds passing by and BC.Mopeds caused substantial short-term increases in air pollution levels on bike lanes, especially in a tunnel. Two-stroke mopeds caused higher concentration peaks than four-stroke mopeds. The contribution to total air pollution concentrations of four-stroke mopeds was larger, because of the higher share of four-strokes. Because of the close proximity of mopeds to cyclists, cyclists air pollution exposure can be largely influenced by moped emissions.

Ultrafine particles and PM2.5 in the air of cities around the world: Are they representative of each other?

Can mitigating only particle mass, as the existing air quality measures do, ultimately lead to reduction in ultrafine particles (UFP)? The aim of this study was to provide a broader urban perspective on the relationship between UFP, measured in terms of particle number concentration (PNC) and PM2.5 (mass concentration of particles with aerodynamic diameter < 2.5 μm) and factors that influence their concentrations. Hourly average PNC and PM2.5 were acquired from 10 cities located in North America, Europe, Asia, and Australia over a 12-month period. A pairwise comparison of the mean difference and the Kolmogorov-Smirnov test with the application of bootstrapping were performed for each city. Diurnal and seasonal trends were obtained using a generalized additive model (GAM). The particle number to mass concentration ratios and the Pearson's correlation coefficient were calculated to elucidate the nature of the relationship between these two metrics.Results show that the annual mean concentrations ranged from 8.0 × 103 to 19.5 × 103 particles·cm−3 and from 7.0 to 65.8 μg·m−3 for PNC and PM2.5, respectively, with the data distributions generally skewed to the right, and with a wider spread for PNC. PNC showed a more distinct diurnal trend compared with PM2.5, attributed to the high contributions of UFP from vehicular emissions to PNC. The variation in both PNC and PM2.5 due to seasonality is linked to the cities' geographical location and features. Clustering the cities based on annual median concentrations of both PNC and PM2.5 demonstrated that a high PNC level does not lead to a high PM2.5, and vice versa. The particle number-to-mass ratio (in units of 109 particles·μg−1) ranged from 0.14 to 2.2, >1 for roadside sites and <1 for urban background sites with lower values for more polluted cities. The Pearson's r ranged from 0.09 to 0.64 for the log-transformed data, indicating generally poor linear correlation between PNC and PM2.5. Therefore, PNC and PM2.5 measurements are not representative of each other; and regulating PM2.5 does little to reduce PNC. This highlights the need to establish regulatory approaches and control measures to address the impacts of elevated UFP concentrations, especially in urban areas, considering their potential health risks.

Indoor air quality, ventilation and their associations with sick building syndrome in Chinese homes

To study the association of indoor air quality and ventilation in Chinese homes with occupants’ sick building syndrome (SBS) symptoms, we performed a study in 32 homes over four seasons in Tianjin, China. Measured indoor environmental parameters were ventilation rate, and concentrations of volatile organic compounds (VOCs), formaldehyde, PM2.5, ultrafine particle and ozone. Occupants reported any sick building syndrome symptoms for the previous three months. Ventilation rates at night in bedrooms were 0.35 h−1, 0.78 h−1, 0.37 h−1 and 0.41 h−1 in spring, summer, autumn and winter, respectively. A low ventilation rate at night (below the median value of 0.45 h−1) significantly increased the risk (adjusted odds ratio, aOR) of mucosal symptom to 2.65 (95% Confidence Interval (CI): 1.16–6.06). The aOR of ultrafine particle for mucosal symptom was 2.37 (95% CI: 1.02–5.49) and for dermal symptoms 3.96 (95% CI: 1.63–9.60). The aOR of ozone for dermal symptoms was 5.86 (95% CI: 1.19–28.99). Dry air perception that indicated a polluted indoor environment was a risk factor for SBS symptoms in Chinese homes.

Fine and ultrafine particles concentrations in vape shops

Vape shops are widespread due to the popularity of electronic cigarettes (e-cigs) as an alternative to tobacco cigarettes. In this study, sixty-seven Southern California vape shops were randomly surveyed for building characteristics, ventilation, and business patterns. Based on the survey results, six representative shops were recruited for real-time measurements of indoor and outdoor fine and ultrafine particles concentrations on a busy and less busy day. Occupancy, vaping frequency, and opening and closing of doors were recorded, and shop air exchange rate was determined. Indoor CO2, relative humidity, and temperature were also recorded. In addition, simultaneous measurements were taken at increasing distances away from a vaping area to assess the mixing and spatial profiles of particle levels inside the shops. During active vaping, real-time indoor particle number concentration and gravimetric-corrected PM2.5 mass concentration across the six vape shops varied from 1.3 × 104 to 4.8 × 105 particles/cm3 and from 15.5 to 37,500 μg/m3, respectively. The spatial profiles of particle number and mass were more uniformly mixed than expected in an indoor environment. Total vaping frequency was the main predictor of particle concentrations inside the vape shops when indoor-outdoor particle mass transfer is minimal (doors closed).

Synergistic effect of the occurrence of African dust outbreaks on atmospheric pollutant levels in the Madrid metropolitan area

The occurrence of African dust outbreaks over specific areas of the Mediterranean basin has been associated with increases in the PM10 concentration levels and also in the mortality rates. Different hypothesis have been proposed in the last years to explain the processes by which African dust storms generates negative health effect over urban areas in southern Europe but are still not clear. Some authors have suggested the existence of an interaction between air pollutants from local sources and the occurrence of African dust outbreaks, with a consequent increase in the risk of mortality due to exposure to these anthropogenic emissions. This study sought to identify such a synergistic effect in the Madrid metropolitan area. To this end, an assessment of the influence of African dust on air quality levels, the vertical structure of the atmosphere over Madrid and daily mortality was carried out. Our results indicated that African dust caused a reduction of the mixing layer height and the surface wind speed, by reducing the amount of solar radiation reaching the ground. These facts favored the accumulation of air pollutants emissions from local anthropogenic sources. Moreover, when the dust contribution to PM10 levels exceeded a threshold value (8 μg/m3), particulate matter mass (PM10, PM2.5) and number (ultra-fine particles) concentration as well as levels of gaseous air pollutants (CO, NO and NO2) registered at urban-background and urban-traffic monitoring sites, increased with statistical significance. In these conditions, it was found a statistically significant increase in risk of daily mortality in the PM10 exposure. Hence, ambient air in Madrid was more toxic during African dust events of increasing intensity due to this synergistic effect. Because it can be envisaged that the frequency, duration and intensity of dust storms will increase in the north of Africa due to climate change, it will be a priority to put forward and assess proposals to mitigate the adverse effects on health, focused on the reduction of air pollutant emissions from local sources, as well as proposals regarding the adaptation of the population in urban areas across the Mediterranean basin.

Exposure assessment of cyclists to UFP and PM on urban routes in Xi'an, China

With the promotion of bicycle sharing, cycling as an active transportation mode is a matter of public interest. However, cyclists' recurrent exposure to traffic-related air pollution is associated with the potential health risks. Quantification of the health risks associated with daily exposure of commuting cyclists to atmospheric pollutants is vital, but barely reported. In this study, real-time mobile measurement campaigns were performed with high time-resolution portable instruments, along two commuting routes in Xi'an, China. We investigated personal exposure and inhaled dose of particulate matter and ultrafine particle (UFP) for cyclists. The results showed cyclists' exposure to average pollutants concentrations: fine particulate matter (PM2.5, 38.6 ± 17.1 μg m−3) and UFP (18,172 ± 11,282 particles cm−3). The exposure “hotspots” of cyclists were identified: intersections, diesel engines, etc. Cyclists' exposure to the highest PM2.5 (46.9 μg m−3) concentrations were observed in morning periods; these were ∼36%/42% higher compared to the afternoon or evening, while the latter periods corresponded to higher UFP concentrations (18,342/18,502 particles cm−3). The measurements of PM2.5 and UFP were clearly higher during autumn months, when compared to summer months. In multivariate models, wind speed was not significant, temperature and local urban background concentrations explained 70.9% the variation of PM2.5, the 67.8% of UFP was explained by temperature, traffic and relative humidity, and each 100 increase in on-road vehicles were associated with increase of 1328 particles cm−3 for UFP exposure in cyclists. Cycling in bike boulevards decreased exposure concentrations by 31.5% for PM and 36.6% for UFP compared to traffic roadsides, moving vehicles were identified as key contributors to PM0.25-0.3 and PM2.0-10 of cyclists' exposure. The potential health risks deserve attention under the mobility and air pollution challenges faced by many metropolitan areas in emerging economies. Our findings could serve to promote better design for low-exposure network of separated bike boulevards.

Investigation of indoor air quality determinants in a field study using three different data streams

Indoor air quality (IAQ) is determined by indoor and outdoor sources and conditions, building characteristics, and occupant behavior. In the field study context where the researcher lacks full control of observational conditions, it is difficult to compare and integrate these determinants because they require such different types and sources of data. This pilot-level project investigated the potential to overcome these limitations by integrating traditional IAQ measurement techniques with questionnaires and analysis of building deficiencies using 3D infrared thermography imaging in two residential multi-apartment buildings. Of the building deficiencies detected by the 3D thermography, missing insulation (MI) correlated best with the IAQ measurements and questionnaire data. Apartments missing more than 5% of insulation in their exterior wall (n = 6) had a significantly higher number concentration of ultrafine airborne particles (diameter < 300 nm) (p = 0.013) and their indoor/outdoor ratio (p = 0.029) compared to apartments where less than 5% of insulation was missing (n = 14). The correlation was driven by apartments where no smoking or use candles or incense was reported. Ultrafine particle concentrations in apartments with combustion sources were higher regardless of the levels of MI. Corner apartments had a higher fraction of MI compared to non-corner apartments (p = 0.002); higher levels of MI were detected in apartments where a resident had an asthma attack in the past 12 months. Our data suggest that integration of different data streams produces a more informative IAQ investigation. This pilot-level study should be performed on a larger scale to examine its wider applicability in the IAQ field.

Determinants of exposure to ultrafine particulate matter, black carbon, and PM2.5 in common travel modes in Istanbul

The personal exposure concentrations of ultrafine particles (UFPs), black carbon (BC), and particulate matter with an aerodynamic diameter ≤2.5 μm (PM2.5) were measured in often-used transport vehicles and routes in Istanbul, Turkey. Exposure to these pollutants were estimated for four different travel modes (bus, metrobus, car, light rail) and five travel routes. Pollutant measurements were simultaneously conducted in the vehicles, and the relationship between pollutant concentrations, meteorological variables, and environmental factors were investigated. The seasonal statistically correlation results indicated that the relation between the meteorological variables and in-vehicle pollutant concentrations were variable with the seasonal differences. UFP concentrations were significantly higher in winter, while in-vehicle BC concentrations were significantly higher in summer. No significant difference was found between the summer and winter in-vehicle PM2.5 concentrations for bus, metrobus and light-rail. There was a significant positive correlation between UFP and BC with transport over roads. The highest average concentrations of UFP, BC, and PM2.5 were observed when car windows were open while traveling, and wind speed negatively affected pollutant concentrations and accounted for between 1 and 29% of their variability. Atmospheric pressure was significantly negatively correlated with BC but positively correlated with UFP and PM2.5. Humidity was a significant factor for UFP (1–12%) and PM2.5 (0–10%), but was not a factor for BC. The pollutant concentrations at the station/platform were the common significant factor for those concentrations in buses, metrobuses and light rail; the variability was determined between 4 and 66% for BC, 3 and 36% for UFP, and 1 and 75% for PM2.5. The time of day was also significant for BC (variation of 3–10%) and UFP (variation of 2–10%) for bus, metrobus, and car trips. The highest average exposures per kilometer for all pollutants was in buses, with exposure levels of UFP, BC, and PM2.5 at 12.3 × 108 particles km−1, 0.40 μg km−1, and 1.33 μg km−1, respectively, while the lowest average exposures per kilometer for all pollutants were in the car with the windows closed and on light rail. It was observed that the metrobus near the highway provided the least concentrations of pollutant exposure.

Temporal variations of ultrafine particle concentrations in aircraft cabin: A field study

Characterization of indoor aerosols in aircraft cabin has been of great interest. However, few studies have presented investigations of ultrafine particle (UFP) concentrations in actual aircraft cabin environment. In this study, we presented the characteristics of UFP number concentration levels, size distributions and temporal variations in fourteen randomly selected domestic commercial flights in China. The results showed that the concentration levels of UFPs in cabin air were 417 ± 1089 counts cm−3, with the lowest values occurred during cruising phase, and the dominant peak at the size channel of 72–100 nm in general. Some of the peak values were observed at the moments of turbulence of air stream or passing through cloud. To further identify contributions of UFPs from interior and outside cabin, CO2 in return air was simultaneously observed as a ventilation tracer to calculate the total airflow rates in those flights. A simplified model was developed to estimate the contribution rates of UFPs from bleed air and cabin interior at cruising phase in selected flights, combing with mass conservation equation under some assumptions. It indicated that, UFPs were commonly derived from unfiltered bleed air system in most of those flights at cruising phase. However, some exceptions were found in some flights, possibly due to unfiltered bleed air system and in-cabin ozonation. This study could be a reference for further understanding the status quo and control strategies of ultrafine particulate pollution in commercial aircraft cabins.

Occupational Exposure to Fine Particles and Ultrafine Particles in a Steelmaking Foundry

Several studies have shown an increased mortality rate for different types of tumors, respiratory disease and cardiovascular morbidity associated with foundry work. Airborne particles were investigated in a steelmaking foundry using an electric low-pressure impactor (ELPI+™), a Philips Aerasense Nanotracer and traditional sampling equipment. Determination of metallic elements in the collected particles was carried out by inductively coupled plasma mass spectrometry. The median of ultrafine particle (UFP) concentration was between 4.91 × 103 and 2.33 × 105 part/cm3 (max. 9.48 × 106 part/cm3). Background levels ranged from 1.97 × 104 to 3.83 × 104 part/cm3. Alveolar and deposited tracheobronchial surface area doses ranged from 1.3 × 102 to 8.7 × 103 mm2, and 2.6 × 101 to 1.3 × 103 mm2, respectively. Resulting inhalable and respirable fraction and metallic elements were below limit values set by Italian legislation. A variable concentration of metallic elements was detected in the different fractions of UFPs in relation to the sampling site, the emission source and the size range. This data could be useful in order to increase the knowledge about occupational exposure to fine and ultrafine particles and to design studies aimed to investigate early biological effects associated with the exposure to particulate matter in the foundry industries.