Ultrafine Particle Emissions Research Articles

Effects of gasoline and polyoxymethylene dimethyl ethers blending in diesel on the combustion and emission of a common rail diesel engine

To reduce the soot emissions of diesel engines, 20% polyoxymethylene dimethyl ethers (PODE) or gasoline by volume is blended in diesel (D80P20 and D80G20) and experimental studies have been carried out to compare the combustion and emission of blend fuels with diesel. Compared to diesel, D80P20 and D80G20 shorten the combustion duration, improve the brake thermal efficiency (BTE), increase the NOx emission and decrease the soot emissions and the number concentrations (NCs) of ultrafine particles (UFPs) in most cases. Strong premixed combustion and enhancement of air entrainment contribute to the highest BTE and NOx emissions of D80G20 at low and partial loads. Strong diffusion combustion contributes to the highest BTE and NOx emissions and the lowest soot and UFPs emissions of D80P20 at medium and high loads.To balance the NOx and soot emissions, PODE and gasoline are simultaneously added in diesel by 10% volume. BTE and NOx emission of D80G10P10 always rank the second. It has the lowest soot and UFPs emissions from 0.16 MPa to 0.48 MPa BMEP among the four fuels. Compared to diesel with original injection timing, suitable delay for D80G10P10 can simultaneously reduce the NOx, soot and UFPs emissions in the whole load range.

Characterization of particulate and gaseous pollutants emitted during operation of a desktop 3D printer

The emission of ultrafine particles (UFP) and gaseous pollutants from 3D printing has been increasingly gaining attention in recent years due to potential health risks. The physical and chemical properties of the emitted particulate matter, however, remain unclear. In this study, we characterized these particles with a focus on their chemical composition and volatility, and measured the gaseous pollutants from desktop 3D printing in a standardized environmental test chamber. Eight types of filaments were tested, including ABS (acrylonitrile butadiene styrene), ASA (acrylonitrile styrene acrylate), HIPS (high impact polystyrene), PETG (polyethylene terephthalate glycol), and PCABS (polycarbonate & ABS). Particle size distribution (PSD), particle number concentration (PNC), particle chemical composition and particle volatility were measured. In addition, volatile and very volatile organic compounds (VOCs and VVOCs) emitted during 3D printing were analyzed. The specific emission rates (SERs) for particles in the size range of 5.6 to 560 nm ranged from 2.0 × 109 (GLASS, a PETG-based filament) to 1.7 × 1011 (ASA) #/min. The particle SERs for ABS were (4.7 ± 1.1) × 1010 #/min. The SERs for total volatile organic compounds (TVOC) varied from 0.2 μg/min (GLASS) to 40.5 μg/min (ULTRAT, an ABS-based filament). Particles started to evaporate extensively from 150 °C. At 300 °C, only 25% of the particle number remained with the size distribution mode peaked at 11 nm. The particles collected on the quartz filter were mainly composed of semi-volatile organic compounds (SVOCs) associated with the plasticizers, flame-retardants, antioxidants of the thermoplastics, and cyclosiloxanes which may be used as lubricants in the 3D printer.

Characterization of Dispersion and Ultrafine-particle Emission Factors Based on Near-roadway Monitoring Part I: Light Duty Vehicles

ABSTRACT This paper presents a comprehensive set of ultrafine particles (UFPs) emission factors (EFs) for heavy duty vehicles (HDVs) as a function of vehicle flow rate, speed, and mode of operation (free flow and congestion) using 664 measurements of UFPs, carbon dioxide (CO2), meteorology and traffic conditions near a major roadway (average daily traffic 300,000 day–1). 5-min samples were collected for 2 to 3 hour time period on 60 days between 2015 and 2018. The average traffic-induced concentration of UFPs was 11,300 pt cm–3 for free flow and 12,400 pt cm–3 for congestion. Results demonstrate that HDVs produce significantly more dispersion (30x) than light duty vehicles (LDVs). The additional dispersion from HDVs results in the minimum pollutant concentrations occurring at the highest vehicle flow rate. EFs for UFPs are determined using inverse modeling based on the calculated CO2 dispersion. This eliminates the need to rely on air-quality models to estimate dispersion. The EFs for HDVs range from 4 × 1014 to 20 × 1014 (pt km–1 veh–1). The variations in EFs are correlated with variations in vehicle flow rate and speed. The average UFP EFs for HDVs are significantly higher (3x) for congestion compared to free flow. UFP EFs for HDVs are more sensitive to speed in congestion compare to in free flow conditions. Thus, even a moderate increase in HDVs speed or mitigation of congestion will have a significant impact on lowering UFP concentrations.

Characterization of air contaminants emitted during laser cutting of carbon fiber-reinforced composite materials

The emission of ultrafine carbonaceous particles during the laser cutting of fiber-reinforced polymer (CFRP) composite materials was investigated. The study was based on characterization of air contaminants emitted during laser cutting of an epoxy-based CFRP material with respect to particle size distribution, particle morphology, and chemical composition. Results indicate that about 90% of the total particulate mass is present as fine particulate matter with an aerodynamic cut-off diameter of 0.25μm, and considerable amounts of ultrafine carbonaceous particulate matter dominated by organic carbon are emitted during high-power laser cutting of CFRP.

Investigation on combustion and emission characteristics of a common rail diesel engine fueled with diesel/n-pentanol/methanol blends

Diesel, n-pentanol, and methanol can form stable, transparent and homogenous fuels. Combustion and emission characteristics of diesel, n-pentanol and methanol blends are investigated on a common rail diesel engine. Test fuels are noted as D100 (diesel), D80P20 (20% n-pentanol and 80% diesel, by vol.), D70P20M10 (20% n-pentanol, 10% methanol and 70% diesel, by vol.) and D70P15M15. At low and partial loads, blend fuels exhibit obviously longer ignition delays, higher peak heat release rates, shorter combustion durations and higher peak combustion temperatures than diesel. At medium and high loads, high oxygen contents result that blend fuels have higher intensities of diffusion combustion than diesel and thereby higher peak combustion temperatures. With the increase of methanol blending ratio, the ignition delay prolongs, the combustion duration shortens, and the peak combustion temperature increases. Also, the soot emissions decrease and NOx emissions increase with methanol. Retarding injection timing may decrease the NOx emissions, whereas increase the soot emissions for D100, D80P20 and D70P20M10. D70P15M15 has the lowest soot and ultrafine particles emissions and suitable retarding can simultaneously decrease the soot and NOx emissions compared to diesel in original injection timing, especially at medium and high loads.

Preterm Birth among Infants Exposed to In Utero Ultrafine Particle Emissions from Aircraft Engines near the Los Angeles International Airport

Ambient air pollution is a known risk factor for adverse birth outcomes, but the role of ultrafine particles (UFPs) is not yet well understood. UFP emissions from aircraft are spread across large residential areas downwind of airports, possibly causing a considerable reproductive health burden.Birth certificate data from the California Department of Public Health was drawn from all births by mothers living in a 200 mi2 area downwind of Los Angeles International Airport (LAX) in 2011 (n=16,268). These records were used to ascertain the presence preterm birth (PTB), as well as maternal covariate information. To assess in utero exposure to UFPs, we input geocoded maternal addresses into a novel geospatial UFP dispersion model that has been validated by extensive ground-level measurements near LAX.We used multiple logistic regression, regressing PTB (live birth < 37 weeks gestation) on UFP concentrations estimated from the dispersion model. We adjusted for maternal factors like age, educational attainment, and race/ethnicity. We further adjusted for measures of air pollution from other sources, like traffic, including PM2.5, nitrogen oxides, and surface ozone to isolate the role of aircraft-related UFPs. An interaction term between UFPs and maternal nativity was included in the model.Among this birth cohort, we found an 11% increase in odds (95% CI: 1.01, 1.22) of PTB per interquartile range of UFP exposure. When stratified by maternal nativity, no increase in PTB among infants of foreign-born mothers was detected (OR = 1.02, 95% CI: 0.90, 1.16) but was detected among infants of US-born women (OR = 1.19, 95% CI: 1.06, 1.32). Effect modification by nativity was borderline statistically significant (p = 0.04).We found increased exposure to aircraft-related UFPs was associated with an elevated risk of PTB, serving as evidence of the reproductive health effects of UFP exposures from aircraft emissions. However, this relationship appears to be modified by maternal nativity.

Characterization of PM2.5 and gaseous emissions during combustion of ultra-clean biomass via dual-stage treatment

Biomass combustion technology is widely considered as an attractive option to remove carbon dioxide emissions and thus could become a viable option for next generation co-combustion power plants with coal. Among biomasses, the faster growing herbaceous biomass (Miscanthus) is relatively inexpensive as a solid fuel but has higher mineral contents (especially high levels of alkali metals) than that of a lignocellulosic biomass (Pitch pine) which leads to ultrafine particle emissions during combustion. This study proposes a dual stage treatment method to extract the inherent minerals in a herbaceous biomass prior to the combustion test. The method consists of an initial treatment with a basic (NaOH) solution and a sequential treatment with an acidic (CH3COOH) solution. To verify the proposed method, we investigated the variations in both the mineral contents and the PM, NOx and SO2 emissions between raw- and treated samples. The experimental results show that sodium, potassium and chloride in the treated herbaceous sample, which are the major minerals that generate ultrafine particles, were removed up to 96.3, 99.4 and 98.3%, respectively. The proposed method is more effective for herbaceous biomasses due to its higher Brunauer–Emmett–Teller (BET) value. Furthermore, the treated herbaceous biomass is even environmentally superior to raw lignocellulosic biomasses currently used in co-combustion power plants with coal in terms of the PM2.5, NOx and SO2 emissions, for which their rejection was measured as 60, 25 and 46%, respectively. These results will help to reduce the energy and costs for De-NOx (selective catalytic reduction, SCR system) and De-SO2 (scrubber) units.

Experimental investigation on microstructure, mechanical properties and dust emission when milling Al-20Mg2Si-2Cu metal matrix composite with modifier elements

Sustainable manufacturing regulations are pushing manufacturing towards decreasing of manufacturing hazards including microparticles and ultrafine particles. Machining process such as milling produces dust that can be harmful for operators’ health. The emission of this dust depends on workpiece materials (microstructure, mechanical properties) and machining conditions. The aim of this paper is to determine the effect of the microstructure and machining conditions on dust emission during dry milling of Al-20Mg2Si-2Cu metal matrix composite with addition of bismuth (Bi) and barium (Ba). Experiments were carried out using dry CNC milling by uncoated carbide tools. An aerodynamic particle sizer (APS) and a scanning mobility particle sizer (SMPS) were used to measure microparticles and ultrafine particles emission, respectively. It was found that the addition of 0.4 wt% Bi and 0.2 wt% Ba changed Mg2Si particle size and improved the hardness of composite. In addition, ultrafine particle number concentration, specific area concentration and mass concentration decreased with the addition of modifiers. It is also confirmed that cutting conditions and microstructure of workpieces have a direct effect on dust emission during the milling process.

Ultrafine Particles Measurement in Printing Industry Across West Malaysia

Ultrafine particles (UFPs) emission generated from devices such as printer and photocopy machines are known as potential risks to human health. However, limited information is available to study UFPs exposure generate from larger printer. Thus, this study aimed to determine the concentration of UFPs such as particle number (PN) and lung deposited surface area (LDSA) and investigates the influence of physical environment factors on UFPs in two types of offset lithographic printing rooms such as monochrome and color, across West Malaysia. The measurements of PN and LDSA were taken by using a condensation particle counter and the diffusion charger dosimeter during the printing activities. The mean values for PN and LDSA are 22215 particles/cm3 and 43 µm2/cm3, respectively. The exposure of UFPs from the monochrome room was found to be significantly higher than the color room (p < 0.001 for PN; p < 0.001 for LDSA) due to variation in the ventilation system. Based on correlation analysis, the physical environment factors, such as relative humidity, temperature, and air movement, were observed to influence the UFPs concentrations in printing room. The findings imply that a good selection of the ventilation system is important to minimize worker’s exposure to UFPs emission.

Size distribution of vehicle emitted primary particles measured in a traffic tunnel

Total and size-resolved concentrations and emission factors are used to compare fleet-averaged vehicle emissions in Pittsburgh, PA in 2002 and 2014. Winter-time traffic tunnel measurements acquired using dual scanning mobility particle sizers (SMPS) over the size range 3–500 nm form the key input for the analysis. Size-resolved mass emission factors were calculated assuming a nanoparticle aggregate model. The ultrafine particle (<30 nm) emissions of diesel vehicles significantly dropped from 2002 to 2014. In the 2014 study, a thermodenuder (TD) was deployed together with the SMPS to measure emissions of non-volatile particles. After evaporation at 250 °C inside the TD, the median diameter of the number-size distribution shifted from 16 nm to ∼7 nm. The total particle number decreased significantly (69%) after evaporating inside the TD, indicating that vehicle emitted particles may be largely externally mixed and that a large fraction of these particles may be purely composed of volatile components. Based on the SMPS-TD measurements, we report a size-resolved volatile-to-non-volatile-component-ratio for vehicle emitted particles. It shows that smaller particles (10–60 nm) emitted by vehicles are dominantly (over 75%) composed of volatile components. We also apportioned the size-resolved particles and non-volatile particle mass and number emission factors for both gasoline and diesel vehicles. Diesel vehicles emitted significantly more ultrafine particles and non-volatile particles than gasoline vehicles.

Influence of smoking rate on ultrafine particle emission of cigarette smoke

Influence of smoking rate on ultrafine particle emission of cigarette smoke

Rotational and translation-free polishing of granite: surface quality and dust particles emission and dispersion

Reducing workers’ exposure to crystalline silica dust is currently a major challenge for granite manufacturing industries. In North America, occupational health regulations are becoming increasingly severe and demanding with respect to quartz dust particle exposure among workers. Of all granite transformation processes, dust control during polishing is the most difficult to realize. During the process, the rotary motion of the tool influences the dust particles, making it harder to capture them. This paper aims to investigate the surface quality, as well as fine particles (FP) and ultrafine particles (UFP) emission and dispersion during dry, rotational and translation-free granite polishing. This research was intended to gather data that could be used to validate dust dispersion simulation results when polishing granite. It was found that workers remain exposed to high concentrations of FP and UFP during this polishing process. In addition, dust particles were found to uniformly contaminate the workspace.

Ultrafine particle emissions from modern Gasoline and Diesel vehicles: An electron microscopic perspective

Ultrafine (<100 nm) particles related to traffic are of high environmental and human health concern, as they are supposed to be more toxic than larger particles. In the present study transmission electron microscopy (TEM) is applied to obtain a concrete picture on the nature, morphology and chemical composition of non-volatile ultrafine particles in the exhaust of state-of-the-art, Euro 6b, Gasoline and Diesel vehicles. The particles were collected directly on TEM grids, at the tailpipe, downstream of the after-treatment system, during the entire duration of typical driving cycles on the chassis dynamometer. Based on TEM imaging coupled with Energy Dispersive X-ray (EDX) analysis, numerous ultrafine particles could be identified, imaged and analyzed chemically. Particles <10 nm were rarely detected. The ultrafine particles can be distinguished into the following types: soot, ash-bearing soot and ash. Ash consists of Ca, P, Mg, Zn, Fe, S, and minor Sn compounds. Most elements originate from lubricating oil additives; Sn and at least part of Fe are products of engine wear; minor W ± Si-bearing nearly spherical particles in Diesel exhaust derive from catalytic coating material. Ultrafine ash particles predominate over ultrafine soot or are nearly equal in amount, in contrast to emissions of larger sizes where soot is by far the prevalent particle type. This is probably due to the low ash amount per volume fraction in the total emissions, which does not favor formation of large ash agglomerates, opposite to soot, which is abundant and thus easily forms agglomerates of sizes larger than those of the ultrafine range. No significant differences of ultrafine particle characteristics were identified among the tested Gasoline and Diesel vehicles and driving cycles. The present TEM study gives information also on the imaging and chemical composition of the solid fraction of the unregulated sub-23 nm size category particles.

Comparison between particulate matter and ultrafine particle emission by electronic and normal cigarettes in real-life conditions.

Electronic cigarettes may be safer than conventional cigarettes as they generate less indoor pollution in terms of particulate matter (PM); however, recent findings in experimental conditions demonstrated that secondhand exposure to PM may be expected from e-cigarette smoking. The aim of the present study was to investigate the emission of PM generated by e-cigarettes and normal cigarettes under real-life conditions. Real-time measurement and comparison of PM and ultrafine particles (UFP) generated by electronic cigarettes with and without nicotine and by normal cigarettes in a 50 m3 office of an Italian comprehensive cancer center was performed. PM mass as PM1, PM2.5, PM7, PM10, total suspended particles (TSP) in μg/m³ and UFP in number of particles per cubic centimeter from 10 to 1,000 nanometers were measured. Outdoor concentrations were measured contemporaneously to compensate for urban background changes. Regardless of their nicotine content, e-cigarettes generated lower PM levels than conventional cigarettes. Notably, nicotine-enriched e-cigarettes produced lower PM levels than their nicotine-free counterparts. E-cigarettes appear to generate less indoor pollution than normal cigarettes and may therefore be safer. Further studies are required to investigate the long-term health-related effects of secondhand e-cigarette exposure.

Mobile and Fixed-Site Measurements To Identify Spatial Distributions of Traffic-Related Pollution Sources in Los Angeles.

Mobile monitoring and fixed-site monitoring using passive sampling devices (PSD) are popular air pollutant measurement techniques with complementary strengths and weaknesses. This study investigates the utility of combining data from concurrent 2-week mobile monitoring and fixed-site PSD campaigns in Los Angeles in the summer and early spring to identify sources of traffic-related air pollutants (TRAP) and their spatial distributions. There were strong to moderate correlations between mobile and fixed-site PSD measurements of both NO2 and NO x in the summer and spring (Pearson's r between 0.43 and 0.79), suggesting that the two data sets can be reliably combined for source apportionment. PCA identified the major TRAP sources as light-duty vehicle emissions, diesel exhaust, crankcase vent emissions, and an independent source of combustion-derived ultrafine particle emissions. The component scores of those four sources at each site were significantly correlated across the two seasons (Pearson's r between 0.58 and 0.79). Spatial maps of absolute principal component scores showed all sources to be most prominent near major roadways and the central business district and the ultrafine particle source being, in addition, more prominent near the airport. Mobile monitoring combined with fixed-site PSD sampling can provide high spatial resolution estimates of TRAP and can reveal underlying sources of exposure variability.

Granite polishing: Effects of polishing parameters and tool paths on part quality and dust emission

Machining is necessary to shape parts but it is also an important source of pollution (such as dust and aerosols) and this constitutes hazards for machine-tools operators. The emission of dust depends on machining conditions, processes, tooling, and machining strategies. The shop floor air quality is thus of great concern when shaping dusty materials such as granite as this process generates harmful dusts. In recent times, the occupational health and safety regulations have become more severe. On the 24th of March 2016, the US department of Labor’s, occupational Safety and Health Administration (OSHA) announced the reduction of the exposure limit for inhalable crystalline silica dust by half. To quickly comply with these new regulations, engineers and researchers must help industries in developing strategies to limit workers risk of exposure to the silica. This paper investigates the emission of fine and ultrafine particle emission when polishing granite as a function of machining conditions and parameters. The main goal is to determine machining conditions leading to less dust emission while maintaining acceptable part quality and productivity.

Effect of minimum quantity lubrication (MQL) on fine and ultrafine particle emission and distribution during polishing of granite

Granite polishing generates aerosols containing fine and ultrafine particles that can be detrimental to occupational health and safety. As the occupational safety regulations are becoming more and more stringer, it is important to find ways of limiting the workers exposure to these particles. Different methods have been proposed to reduce the dust emission at the source during polishing of granite. They include using ventilation to capture or redirect the dust and using of wet polishing process to help settling down quicker the generated particles. Traditionally, the wet machining processes are conducted using flood lube but given the costs associated with this lubricating condition, in most machining sectors, the use of minimum quantity lubrication or cooling, also known as MQL machining is being tried. MQL polishing could be a cost effective way of reducing the dust generation at the source when polishing granites. Knowledge on the distribution and behavior of semi-wet particle could also help in designing other methods and apparatus for capturing or taking the dust away of the working environment.This paper investigates fine and ultrafine particle emissions during polishing tests under minimum quantity lubrication (MQL) conditions as compared to dry polishing. The MQL polishing is done using water at different flow rates and their effects on the working environment air quality investigated. It is found that the effectiveness of water MQL in particle reduction depends on size of particles considered.

Airborne ultrafine particles in a Pacific Island country: Characteristics, sources and implications for human exposure

The Pacific Islands carry a perception of having clean air, yet emissions from transport and burning activities are of concern in regard to air quality and health. Ultrafine particle number concentrations (PNCs), one of the best metrics to demonstrate combustion emissions, have not been measured either in Suva or elsewhere in the Islands. This work provides insight into PNC variation across Suva and its relationship with particle mass (PM) concentration and composition. Measurements over a short monitoring campaign provide a vignette of conditions in Suva. Ambient PNCs were monitored for 8 day at a fixed location, and mobile PNC sampling for two days. These were compared with PM concentration (TSP, PM10, PM2.5, PM1) and are discussed in relation to black carbon (BC) content and PM2.5 sources, determined from elemental concentrations; for the October 2015 period and longer-term data. Whilst Suva City PM levels remained fairly low, PM2.5 = 10–12 μg m−3, mean PNC (1.64 ± 0.02 × 104 cm−3) was high compared to global data. PNCs were greater during mobile sampling, with means of 10.3 ± 1.4 × 104 cm−3 and 3.51 ± 0.07 × 104 cm−3 when travelling by bus and taxi, respectively. Emissions from road vehicles, shipping, diesel and open burning were identified as PM sources for the October 2015 period. Transport related ultrafine particle emissions had a significant impact on microscale ambient concentrations, with PNCs near roads being 1.5 to 2 times higher than nearby outdoor locations and peak PNCs occurring during peak traffic times. Further data, particularly on transport and wet-season exposures, are required to confirm results. Understanding PNC in Suva will assist in formulating effective air emissions control strategies, potentially reducing population exposure across the Islands and in developing countries with similar emission characteristics.Suva's PNC was high in comparison to global data; high exposures were related to transport and combustion emissions, which were also identified as significant PM2.5 sources.

Dilution effects on ultrafine particle emissions from Euro 5 and Euro 6 diesel and gasoline vehicles

Dilution and temperature used during sampling of vehicle exhaust can modify particle number concentration and size distribution. Two experiments were performed on a chassis dynamometer to assess exhaust dilution and temperature on particle number and particle size distribution for Euro 5 and Euro 6 vehicles. In the first experiment, the effects of dilution (ratio from 8 to 4 000) and temperature (ranging from 50 °C to 150 °C) on particle quantification were investigated directly from tailpipe for a diesel and a gasoline Euro 5 vehicles. In the second experiment, particle emissions from Euro 6 diesel and gasoline vehicles directly sampled from the tailpipe were compared to the constant volume sampling (CVS) measurements under similar sampling conditions. Low primary dilutions (3–5) induced an increase in particle number concentration by a factor of 2 compared to high primary dilutions (12–20). Low dilution temperatures (50 °C) induced 1.4–3 times higher particle number concentration than high dilution temperatures (150 °C). For the Euro 6 gasoline vehicle with direct injection, constant volume sampling (CVS) particle number concentrations were higher than after the tailpipe by a factor of 6, 80 and 22 for Artemis urban, road and motorway, respectively. For the same vehicle, particle size distribution measured after the tailpipe was centred on 10 nm, and particles were smaller than the ones measured after CVS that was centred between 50 nm and 70 nm. The high particle concentration (≈106 #/cm3) and the growth of diameter, measured in the CVS, highlighted aerosol transformations, such as nucleation, condensation and coagulation occurring in the sampling system and this might have biased the particle measurements.

World Medical Association’s Concern Regarding Effects of Ultrafine Particles and Vehicular Emissions: Report from 65th General Assembly in Durban, South Africa

Recent predictions from the World Health Organization indicate urban air pollution is the cause of nearly four million deaths annually. In particular, diesel soot, abundant in ultrafine (nanoscale) size, is shown to be carcinogenic and affects the cardiovascular and respiratory systems. Diesel soot contains mainly black carbon and adsorbed carcinogenetic substances as PAHs. Furthermore, soot and methane are both recognized as remarkable greenhouse-effect drivers. In its 65th General Assembly, the World Medical Association (WMA) recommended a series of measures to its member organizations to follow through via their respective governments. The recommended measures include utilizing the best available technology (BAT) for all new diesel vehicles and soot-filter retrofits for all in-use engines, curbing on nanosize soot emission, and further scrutiny of health impacts due to ultrafine particles, instilling further preventing measures and public awareness programs, protection against ultrafine particles in aircraft cabins, trains and alike, and to shift urban traffic to public transportation systems.