PM Size Distribution Research Articles

Particulate matter emission characteristics of spruce, sunflower and maize: A comparison between nominal and reduced output in a small-scale boiler

The applicability of spruce, sunflower and maize for residential heating was investigated. Emission factors of gaseous and PM pollutants were established at both nominal and reduced output. Since automatic pellet boilers often operate at reduced output, understanding the differences in PM release and behavior is crucial. The emission factors for sunflower reached the highest values at 111.6 mg MJ−1 and 139.2 mg MJ−1 for nominal and reduced output, respectively. PM emission factors reached 49.5/39.5 mg MJ−1 for maize and 8.6/21.4 mg MJ−1 for spruce. It was shown that PM size distribution does not vary significantly between nominal and reduced output and is highly dependent on the fuel composition. The PM size peak was in the range of 0.377–0.596 μm for sunflower, 0.252–0.377 μm for maize, 0.152–0.252 μm for spruce at nominal output and 0.0941–0.152 μm for spruce at reduced output. The entrainment of coarse ash particles was found to be negligible. Cd, Pb, Tl and Sb were found almost exclusively on emitted particles, due to their high volatility and modes of occurrence. The release of inorganic matter into the flue gas was severely inhibited in maize due to the formation of refractory phases.

Measurement of ambient particulate matter (PM1.0, PM2.5 and PM10) in Khulna City of Bangladesh and their implications for human health

Atmospheric particles have been significantly affecting urban air quality and urban-oriented living in an increasing share of the population in Bangladesh. This study assessed the concentration of PM1.0, PM2.5, and PM10 in Khulna, one of the largest cities in Bangladesh located near the Bay of Bengal. The maximum average concentrations were recorded 415 ± 184.01 µg/m3 for PM10, 302 ± 109.89 µg/m3 for PM2.5, and 143 ± 45.05 µg/m3 for PM1.0. These values are several times higher than the World Health Organization air quality standard and Bangladesh National Ambient Air Quality Standard. According to the size and fractional distribution of PM, most of the monitoring locations were dominated by fine particles. Carcinogenic and non-carcinogenic risks due to exposure to ambient PM1.0, PM2.5 and PM10 were also quantified to illustrate the relevant potential human health risks. The excess lifetime cancer risk (ELCR) values of PM1.0 ranged from 8.6E0–4 to 6.0E–07 and PM2.5 varied between 8.6E–04 and 6.0E–07 exceeded the allowable limit at every location indicating the potential cancer-developing risk to the urban population. The health quotient (HQ) values also crossed the least permissible value at most of the locations depicting strong non-carcinogenic risks. Average HQ values of PM2.5 varied from 1.07 to 20.13 while PM10 ranged from 0.44 to 8.3. This research revealed children and elderly people as the most vulnerable age groups with the highest carcinogenic risks through exposure to atmospheric PM in Khulna city. Therefore, air pollution reduction plans and risk mitigation strategies should be developed and implemented by the government authorities.Graphical

One-Year-Long, Comprehensive Analysis of PM Number and Mass Size Distributions in Warszawa (Poland)

Abstract The properties of particulate matter PM, including its impact on the environment and human health, depend mainly on the size (more precisely: size distribution) of the particles since the size is usually dependent on the processes/sources of the PM. This work presents the results of a one-year-long measurement campaign of PM. PALAS Fidas 200 from Airpointer air quality station was used. The PM was measured in Warsaw, Poland continuously from 1st May 2022 to 30th April 2023; size distribution was recorded with 120 s intervals and averaged in 3600 s periods. It was found, that the number and the mass size distribution varied depending on the averaging period (different hours of the day, different days of the week, and different months of the year). Additionally, the authors determined the periods of impact on selected sources (traffic emission, municipal emission, and industrial emission) on the number and mass size distributions of PM at the sampling site. Monitoring of number and mass size distributions of PM is a relatively easy and more cost-effective method than analysing the chemical composition of PM. Therefore, is crucial to develop a method of identifying sources of PM based on size distributions. It was found that such a method can be in the future as successful in source apportionment as in the analysis of chemical compositions.

Emission Characteristics of Particulate Matter from Boiling Food

Cooking food in water or soup, such as hot pot, is a widely used cooking method in China. This type of cooking requires no oil and cooks at a lower temperature, but that does not mean it produces fewer pollutants or is less harmful. There are few research studies on the emission characteristics and mechanisms of particulate matter emissions when eating hot pot (the boiling process), which leads to the unreasonable design of ventilation systems for this kind of catering. In this paper, the effects of boiling different ingredients (including noodles, potatoes, fish, tofu, meatballs, and pork) on particle number concentration emissions were studied. The particle number concentration and particle size distribution of PM with diameters of 0.3 μm and less, 0.3–0.5 μm and 0.5–1.0 μm (PM0.3, PM0.3–0.5 and PM0.5–1.0, respectively) were measured in an experimental chamber. The food type and shape showed very little change in the PM emission characteristics of boiling. When the boiling state was reached, the number concentration, particle size distribution, and arithmetic mean diameter of particles all fluctuated within 60 s. The emission characteristics of particles produced by boiling water and heating oil were compared. Heating oil produced more small particles, and boiling water released more large particles. Transient and steady methods were used to calculate the emission rate of particles, and the steady-state calculation has a high estimation of the emission rate.

Chemically speciated mass size distribution, particle density, shape and origin of non-refractory PM<sub>1</sub> measured at a rural background site in central Europe

Abstract. Seasonal variability of non-refractory PM1 (NR-PM1) was studied at a rural background site (National Atmospheric Observatory Košetice – NAOK) in the Czech Republic to investigate the effect of regional and long-range atmospheric transport in central Europe. NR-PM1 measurements were performed by compact time-of-flight aerosol mass spectrometry (C-ToF-AMS), and the chemically speciated mass size distributions, density, shape, and origin were discussed. Average PM1 concentrations, calculated as the sum of the NR-PM1 and the equivalent black carbon (eBC) concentrations measured by an aethalometer (AE), were 8.58 ± 3.70 µg m−3 in summer and 10.08 ± 8.04 µg m−3 in winter. Organics were dominant during both campaigns (summer/winter: 4.97 ± 2.92/4.55 ± 4.40 µg m−3), followed by SO42-in summer (1.68 ± 0.81/1.36 ± 1.38 µg m−3) and NO3- in winter (0.67 ± 0.38/2.03 ± 1.71 µg m−3). The accumulation mode dominated the average mass size distribution during both seasons, with larger particles of all species measured in winter (mode diameters: Org: 334/413 nm, NO3-: 377/501 nm, SO42-: 400/547 nm, and NH4+: 489/515 nm) indicating regional and long-range transport. However, since the winter aerosols were less oxidized than the summer aerosols (comparing fragments f44 and f43), the importance of local sources in the cold part of the year was still enough to be considered. Although aged continental air masses from the south-east (SE) were rare in summer (7 %), they were related to the highest concentrations of PM1, eBC, and all NR-PM1 species, especially SO42- and NH4+. In winter, slow continental air masses from the south-west (SW) (44 %) were linked to inversion conditions over central Europe and were associated with the highest concentrations among all NR-PM1 species as well as PM1 and eBC. Average PM1 material density (ρm) corresponded to higher inorganic contents in both seasons (summer: ∼ 1.30 g cm−3 and winter: ∼ 1.40 g cm−3). During episodes of higher mass concentrations ρm ranged from 1.30–1.40 g cm−3 in summer and from 1.30–1.50 g cm−3 in winter. The dynamic shape factors (χ) decreased slightly with particle mobility diameter (Dm) in both seasons. This study provides insights into the seasonal effects and air mass variability on aerosol particles, focusing on episodes of high mass and number concentrations measured at a central European rural background site.

Particulate number emissions during cold-start with diesel and biofuels: A special focus on particle size distribution

The share of biofuels in the transportation sector is increasing. Previous studies revealed that the use of biofuels decreases the size of particles (which is linked to an increase in particulate toxicity). Current emission regulations do not consider small particles (sub-23 nm); however, there is a focus in future emissions regulations on small particles. These and the fact that within cold-start emissions are higher than during the warmed-up operation highlight the importance of a research that studies particulate matter emissions during cold-start. This research investigates the influence of biofuel on PN and PM concentration, size distribution, median diameter and cumulative share at different size ranges (including sub-23 nm and nucleation mode) during cold-start and warm-up operations using diesel and 10, 15 and 20% mixture (coconut biofuel blended with diesel). During cold-start, between 19 and 29% of total PN and less than 0.8% of total PM were related to the nucleation mode (sub-50 nm). Out of that, the share of sub-23 nm was up to 9% for PN while less than 0.02% for PM. By using biofuel, PN increased between 27 and 57% at cold-start; while, the increase was between 4 and 19% during hot-operation. The median diameter also decreased at cold-start and the nucleation mode particles (including sub-23 nm particles) significantly increased. This is an important observation because using biofuel can have a more adverse impact within cold-start period which is inevitable in most vehicles’ daily driving schedules.

Mass size distributions, composition and dose estimates of particulate matter in Saharan dust outbreaks

The present study highlights the importance of examining the contribution of Saharan dust (SD) sources not only in terms of overall mass contribution but also in terms of composition, size distribution and inhaled dose. The effect of SD intrusions on PM and the respective major and trace metals mass concentrations and size distributions was investigated in a suburban site in Athens, Greece. SD events were associated, on average, with lower boundary layer heights (BLH) compared to the non-Sahara (nSD) dust days. During SD events, PM1-10 concentrations showed an increasing trend with increasing atmospheric BLH, in contrary to the fine PM (PM1). Generally, increased PM1 and CO (i.e. anthropogenic origin) levels were observed for BLH lower than around 500 m. The average contribution of SD to PM10 and PM2.5 mass concentration was roughly equal to 30.9% and 19.4%, respectively. The mass size distributions of PM and specific major and trace elements (Na, Al, Si, S, Cl, K, Ca, Fe, and Zn) displayed a somewhat different behavior with respect to the mass origin (Algeria-Tunisia vs Libya-Egypt), affecting in turn the regional deposition of inhaled aerosol in the human respiratory tract (HRT). The average PM deposited mass in the upper and lower HRT was 80.1% (Head) and 26.9% (Lung; Tracheobronchial and Pulmonary region) higher for SD days than for nSD days. Higher doses were estimated in the upper and lower HRT for the majority of the elements, when SD intrusions occurred, supporting the increasingly growing interest in exploring the health effects of SD. Only the mass deposition for S, and Na in the lower HRT and Zn in the upper HRT was higher in the case of nSD.

Influence of 1-butanol and 1-pentanol addition to diesel fuel on exhaust and noise emissions under stationary and transient conditions

There is a growing interest in using long-chain alcohols, i.e. butanol and pentanol, in the transport sector, as a consequence of their potential production from residual biomass via fermentative processes. There is evidence that incorporation of alcohols to diesel fuel enables to overcome the well-known smoke-NOx trade-off under steady state compression ignition engine operation. Nevertheless, the impact of long-chain alcohols under engine transient conditions is not understood and their behavior under Worldwide Harmonized Light Vehicles Test Procedure (WLTP) cycle has not been reported. This investigation addresses the above-mentioned research gaps by characterization of noise and exhaust emissions (CO, total hydrocarbon content or THC, NOx and particulate matter or PM mass, PM number and PM distribution) of a diesel engine running on ultra-low sulfur diesel (ULSD) fuel and its mixtures with 1-pentanol and 1-butanol under stationary and transient conditions (WLTP).Transient PM number, mass and size distribution have been monitored using Dekati electrical pressure low impactor ELPI + coupled by Dekati Fine Particle Sampler FPS-4000, whereas transient gaseous emissions have been measured with Horiba Mexa 7100D. Increasing the long-chain alcohol content in fuel blends, significantly reduces PM number and mass for both stationary and WLTP tests, being mainly attributed to oxygen content of 1-butanol and 1-pentanol. Addition of long-chain alcohols causes a decrease of emitted NOx in stationary operation, but the opposite trend was found under WLTP. Noise levels seem to slightly increase with the use of higher alcohol/ULSD fuel mixtures. Overall, it may be concluded that utilization of higher alcohol/ULSD fuel blends appears as a favorable substitute to straight ULSD fuel.

Susceptibility of individuals with lung dysfunction to systemic inflammation associated with ambient fine particle exposure: A panel study in Beijing

BackgroundThe underlying mechanism on the susceptibility of chronic obstructive pulmonary disease (COPD) patients to air pollution has yet to be clarified. ObjectivesBased on the COPD in Beijing (COPDB) study, we examined whether lung dysfunction contributed to pollutant-associated systemic inflammation in COPD patients. MethodsProinflammatory biomarkers including interleukin-8 (IL-8) and tumor necrosis factor α (TNFα) were measured in serum samples collected from 53 COPD and 82 healthy participants. Concentrations of particulate matter with aerodynamic diameter ≤ 2.5 μm (PM2.5), carbonaceous components in PM2.5, and PM size distribution were continuously monitored. Linear mixed effects models were used to examine the associations of biomarker differences with particle exposure, between COPD and healthy participants, and across subgroups with different levels of lung dysfunction. ResultsCOPD patients showed higher differences in IL-8 and TNFα levels associated with exposure to measured pollutants, comparing to healthy controls. In advanced analysis, particle-associated differences in IL-8 and TNFα levels were higher in participants with poorer lung ventilation and diffusion capacity, and higher ratio of residual volume. For example, an interquartile range increase in average PM2.5 concentration 2 weeks before visits was associated with a 15.7% difference in IL-8 level in participants with the lowest ratio of measured value to predicted value of forced expiratory volume in 1 s (FEV1%pred) (65.2%), and the association decreased monotonically with increasing FEV1%pred. Associations between differences in TNFα level and average ultrafine particle concentration 1 week before visits increased gradually with increasing ratio of measured value to predicted value of residual volume/total lung capacity. ConclusionsCOPD patients, especially those with poorer lung function, are more susceptible to systemic inflammation associated with fine particle exposure.

Emission characteristics of PM, heavy metals, and dioxins in flue gases from sintering machines with wet and semi-dry flue gas desulfurization systems.

In iron and steel industry, sintering process releases large amount and different kinds of pollutants. Most sintering plants had applied the dust removal system and the flue gas desulfurization (FGD) system for exhaust treatment in China. Previous studies of FGD systems were focused on the removal of air pollutants from coal-fired boiler, rather than in the iron ore sintering process. In this study, PM, heavy metals, and dioxins were sampled at a China typical sintering plant with both wet and semi-dry FGDs. The results showed that the PM removal efficiencies of the wet and semi-dry FGDs were 29.44% and 22.28%, respectively. The size distributions of PM were at the range of 0.7~4.7 μm in the inlet flue gases of both FGDs. The overall removal efficiencies of heavy metals were above 65%. In both outlet flue gases, Pb as the most elements accounted for 93.33% of total at the wet FGD, while Pb, Cr, and Zn accounted for 76.34% at the semi-dry FGD. The proportions of gaseous heavy metals in the inlets of both FGDs were improved than those in the outlets. Furthermore, the total emission amounts of dioxins in both inlets and outlets of the flue gases were 0.0385 ng-TEQ/m3 and 0.0248 ng-TEQ/m3 at the wet FGD and 0.0078 ng-TEQ/m3 and 0.0050 ng-TEQ/m3 at the semi-dry FGD, respectively. The overall removal efficiencies of dioxins were all above 35%. The polychlorinated dibenzofurans (PCDFs) ratio in the dioxins lightly increased from 84.46 to 88.80% through wet FGD, while it decreased from 80.83 to 44.35% in semi-dry FGD.

A comprehensive study on gas and particle emissions from laser printers: Chemical composition and health risk assessment

In this study, a general evaluation of indoor air quality (IAQ) in an office room with intense printing activity was investigated. Instantaneous peaks of PM2.5 and O3 were observed when the printer was working, and the concentrations were decreased significantly on idle times. Size distribution of PM showed a remarkable contribution of quasi-ultrafine mode particles to the total aerosol mass. Polycyclic aromatic hydrocarbons (PAHs) and elemental carbon (EC) occupied an insignificant percent of the aerosol mass, while organic carbon (OC) together with elements were noted to be significant. Carcinogenic and non-carcinogenic health risks due to the PM exposure were evaluated by using size-dependent deposition fractions in the respiratory tract. Hazard index (HI) was calculated as 5.5 × 10−5 for the PAHs and 2.2 × 10−1 for heavy metal exposure as the sum of inhalation, ingestion and dermal exposures. Cancer risk (CR) values were obtained to be 6.3 × 10−7 and 6.4 × 10−6 for the inhalation of PAHs and heavy metals, respectively. As a result of the higher concentration of the VOCs, total CR higher than 1.3 × 10−5 was estimated, while total hazard quotient (HQ) value was noticed to be 9.9 × 10−2 in the office.

Review of PM Oxidative Potential Measured with Acellular Assays in Urban and Rural Sites across Italy

This work is an overview of the oxidative potential (OP) values up to date measured in Italy, with the aim to provide a picture of the spatial and seasonal variability of OP in the various geographical areas across Italy. The summarized works used the common acellular assays-based dithiothreitol (OPDTT), ascorbic acid (OPAA), glutathione (OPGSH), and 2′,7′-dichlorodfluorescein (OPDCFH) assays. The paper describes the association of OP responses with PM chemical composition, the sensitivity of various acellular OP assays to PM components and emission sources, and PM size distribution of the measured OP values. Our synthesis indicates that crustal and transition metals (e.g., Fe, Ni, Cu, Cr, Mn, Zn, and V), secondary ions and carbonaceous components (elemental carbon, EC, organic carbon, OC and water soluble carbon, WSOC) show significant correlations with OP across different urban and rural areas and size ranges. These chemical species are mainly associated with various PM sources, including residual/fuel oil combustion, traffic emissions, and secondary organic aerosol formation. Although the OP assays are sensitive to the same redox-active species, they differ in the association with PM chemical components. The DDT assay is mainly sensitive to the organic compounds that are mostly accumulated in the fine PM fraction, i.e., tracers of burning sources, and redox active organics associated with other markers of photochemical aging. In contrast, OPAA and OPGSH were mostly responsive to metals, mainly those related to non-exhaust traffic emissions (Cu, Zn, Cr, Fe, Ni, Mn, Sn, Cd, Pb), that are mainly accumulated in the coarse PM. Among the investigated sites, our synthesis shows larger OP values in Trentino region and the Po Valley, that may be explained by the high density of anthropogenic sources, and the orographic and meteorological characteristics, that favor the pollutants accumulation and aerosol photo-oxidative aging.

Characterizing early stage sub-micron particle formation during pulverized coal combustion in a flat flame burner

Mineral matter evolution, soot formation, and soot oxidation are the governing processes for fine particle evolution during the early stages of pulverized coal combustion. Soot and ash can be simultaneously present in PM 0.1, and experimental results obtained to understand early stage particle formation can be ambiguous if the two are not independently evaluated. A sampling system proposed in this work differentiates between soot and mineral matter by employing a high temperature furnace downstream of the sampling system, supplied with sufficient oxygen to oxidize the soot in the sampled aerosol stream. The stream can be routed either through the furnace or bypassing it. In the bypass configuration, the SMPS measures the total PM size distribution. In the flow-through configuration, the SMPS measures the ash PM size distribution, and the difference identifies the contributions from the soot aerosols. This study has shown that there is a high probability of confounding effects in experimental measurements of early stage ultra-fine particulate matter evolution, and the effects were shown to exist at different conditions and with different coals. The results show that for PRB coal combustion, as residence time increases from 9 ms to 33 ms, the volume of total PM 0.1 decreases by 68%, and the ash PM 0.1 increases by 600%, whereas for Hongshayuan lignite coal, the volume of total PM 0.1 increases by 275%, and ash PM 0.1 increases by 939%. These results indicated that soot constitutes a major part of PM 0.1 during the early stages of fine particle evolution.

An experimental study of the role of biodiesel on the performance of diesel particulate filters

The study investigates the impact of the physical properties of biodiesel particulate matter on the performance of diesel particulate filters (DPF). Filtration efficiency (FE) and pressure drop (PD), as a function of loading time, were studied on a DPF for a range of biodiesel fuels with varying fuel molecular oxygen content from 0% (diesel) to 14%. The change in the oxygen content of the fuel resulted in diesel particle matter (DPM) with significantly different physical properties. FE and PD were investigated during the deep bed filtration stage, chosen because it presents the start of the loading process, which is a crucial step for high performance filtration. Firstly, we investigated the influence of the size distribution of various particles on the deep bed filtration, wherein size distributions of PM were measured before and after the DPF. The results show that for all fuels the FE is higher for smaller particles, as diffusion is the dominant process governing the filtration in tested conditions. Further we found that FE for biodiesel particles were up to 10% lower than for diesel particles at the beginning of the loading process, but with that difference diminishing as the filter fully loads. This result is attributed to the increase in the particulate fractal dimension with a higher biodiesel fraction resulting in more compact particles with lower diffusion coefficients. In addition, the study also demonstrated that the change of FE during the loading process is dependent on the physical properties of DPM. DPF performs differently for biodiesel soot as compared to diesel soot, with biodiesel soot causing higher PD for the same mass of the soot loaded on the DPF. This effect was attributed to the smaller primary particulate size of the biodiesel particles. The results presented in this study will further facilitate understanding of the filtration processes of particulate matter and validate detailed filtration models for the prediction of the filtration efficiency (FE) and pressure drop (PD) depending on the particle morphological properties.

Performance and emissions of a compression-ignition direct-injected natural gas engine with shielded glow plug ignition assist

Performance and emissions experiments were conducted on a compression-ignition direct-injected natural gas engine (DING) equipped with a shielded glow plug ignition assist system. Tests were conducted at three different intake pressures (34.5 kPag, 68.9 kPag, 103.4 kPag), and four nominal (targeted) equivalence ratios (0.2, 0.3, 0.4, 0.5). CH4, NOx, CO and PM emissions were measured and analyzed, showing that emissions levels are influenced by the DING engine’s combustion modes and intake pressure. Premixed combustion which dominates at low equivalence ratios resulted in higher levels of CH4 and NOx emissions, while mixing-controlled combustion, which develops at higher equivalence ratios, resulted in elevated CO and PM levels. Higher intake pressure was found to improve all emissions levels. The most significant effect was the reduction of PM and CO emissions due to improved fuel charge mixing and air entrainment that results from a pressure-driven momentum increase of the engine’s air swirl field. Brake specific emissions and fuel consumption were estimated and compared against levels reported in the literature for dual-fuel port-injection, and High-Pressure Direct-Injection (HPDI) natural gas engines. The most significant finding was that the DING engine exhibits lower fuel consumption and PM emissions levels when compared to values reported in the literature for HPDI engines. The PM emissions advantage was attributed to a higher proportion of premixed combustion and the absence of a diesel pilot in DING engine operation. Lastly, PM size distributions were analyzed, showing that the DING engine produces PM that is smaller than PM of a conventional diesel engine, but similar to the PM reported in the literature for HPDI engines.

Urban environment as a factor modulating metals deposition in the respiratory track and associated cancer risk

The aim of this study was to compare the inhalation cancer risk posed by PM-bound As, Cd, Pb, Ni and Cr(VI) concentrations in typical urban environment and to differentiate this risk between PM size fractions and population age-groups. Additionally inhalation deposition metrics were used to characterize risks posed by PM of highway (H)-, street canyon (SC)- and residential (RA) origin. Aerosol samples were collected in the cities of Zabrze and Katowice (Poland) using Dekati cascade impactors. Regardless of the location metals were primarily associated with particles less than 1 μm. For sites, where the PM size distribution was bi-modal (SC in Zabrze and Katowice and RA in Zabrze) and the maxima of metal mass distribution occurred in both accumulation and coarse modes, the metal was predominantly deposited in head airways region. Sites characterized by an uni-modal distribution (RA in Katowice, H in Katowice and SC in Zabrze) were found to favor pulmonary deposition. The overall mass deposition of metals in the respiratory tract in residential; highway and street canyon environments were: 0.51; 0.54 and 0.61, respectively. Street canyon concentrations were therefore most hazardous. Depending on the specific compartment of the respiratory tract, average metal mass deposition amounts varied from 0.05 to 0.53 of its ambient concentration. ILCR values were up to 10E-03 for adults versus 10E-05 for infants. Adults were mostly exposed near street canyons, while infants and children were mostly susceptible near residential and highway environments.

Diurnal and seasonal trends and source apportionment of redox-active metals in Los Angeles using a novel online metal monitor and Positive Matrix Factorization (PMF)

In the present study, we identified the sources of four redox-active metals, including Iron (Fe), Chromium (Cr), Cupper (Cu), and Manganese (Mn) and quantified the contribution of these sources to PM2.5 concentrations in central Los Angeles, California, by employing time-resolved measurements (i.e., a time resolution of 2 h) with a recently developed online metal monitor and Positive Matrix Factorization (PMF). Size distribution of ambient PM (14 nm–10 μm) was measured using the Scanning Mobility Particle Sizer (SMPS) and Optical Particle Sizer (OPS). Auxiliary variables were also collected, including elemental (EC) and organic carbon (OC), gaseous pollutants (NO2 and O3), meteorological parameters (including relative humidity (RH) and temperature), and traffic data (for heavy- (HDVs) and light-duty vehicles (LDVs)). A 4-factor solution was found to be optimum for the chemically-speciated dataset, whereas a 5-factor solution appeared to be most plausible for the size distribution data. The factors included fresh traffic, soil/road dust, urban background aerosol, secondary aerosol, and nucleation (only resolved for the size distribution data). Fresh traffic was the major contributor to Fe and Cu concentrations, whereas Cr was mostly found in the urban background aerosol (reflecting a mixture of small local sources as well as aged traffic emissions), and Mn mostly came from both soil/road dust and was to a lesser degree found in urban background aerosol. Secondary aerosol did not contribute to the concentrations of any of these metals, but was associated with very high loading of OC, as expected. Even though the urban background aerosol and secondary aerosol appeared to be characterized by “aged” particles and have a rather homogeneous spatial distribution, the reactions and processes involved in their formation are entirely different. Our results provide insights into the sources of redox-active metals in central Los Angeles. They also underscore the benefits of novel measurement techniques for PM-bound metals, which could enhance our understanding of the sources of atmospheric aerosols by providing us with measurements with finer time resolutions that otherwise would not have been possible using traditional filter-based measurement techniques.

Measuring indoor particulate matter concentrations and size distributions at different time periods to identify potential sources in an office building in Taipei City

In this study, indoor PM concentrations and size distributions were measured at different time periods to identify the sources of indoor PM in an office building. The measurement results indicate that indoor PM concentration was affected by outdoor air quality conditions, building ventilation system operations, and indoor activities. The results demonstrated that the indoor PM10 concentration was significantly affected by the outdoor air quality conditions when the ventilation system was turned on. However, the outdoor and indoor PM10 concentrations were less correlated when the ventilation system was turned off. Moreover, fine PM was the major component of the indoor PM in the air supply device. Additionally, the indoor particle mass size distributions exhibited a triple-mode pattern on working days. The dominant mode was at approximately 0.33 μm, and the other two modes were at 2–4 μm and 12–14 μm. Specifically, an extremely coarse mode at 12–14 μm could be observed during working hours, demonstrating that these coarse particles in the indoor environment were caused by indoor activities during working hours. Moreover, the indoor particle mass size distributions on the holidays exhibited a stable double-mode pattern, suggesting that the coarse particles in the indoor air completely vanished due to sedimentation because of less indoor activities on the holidays.

The influence of oxygenated fuels on transient and steady-state engine emissions

This research studies the influence of oxygenated fuels on transient and steady-state engine performance and emissions using a fully instrumented, 6-cylinder, common rail turbocharged compression ignition engine. Beside diesel, the other tested fuels were based on waste cooking biodiesel (primary fuel) with triacetin (highly oxygenated additive). A custom test was designed for this study to investigate the engine performance and emissions during steady-state, load acceptance and acceleration operation modes. Furthermore, to study the engine performance and emissions during a whole transient cycle, a legislative cycle (NRTC), which contains numerous discrete transient modes, was utilised. In this paper, the turbocharger lag, engine power, NOx, PM, PN and PN size distribution were investigated. During NRTC the brake power, PM and PN decreased with fuel oxygen content. During steady-state operation, compared to diesel, the oxygenated fuels showed lower indicated power, while they showed higher values during acceleration and turbocharger lag. During acceleration and load increase modes, NOx, PM and PN peaked over the steady-state counterpart, also, the accumulation mode count median diameter moved toward the larger particle sizes. Increasing the fuel oxygen content increased the indicated specific NOx and PN maximum overshoot, while engine power, PM, PN and PM maximum overshoot decreased. Also, the accumulation mode count median diameter moved toward the smaller particle sizes.

Composition, size distribution, optical properties, and radiative effects of laboratory-resuspended PM<sub>10</sub> from geological dust of the Rome area, by electron microscopy and radiative transfer modelling

Abstract. In this work, new information has been gained on the laboratory-resuspended PM10 fraction from geological topsoil and outcropped rocks representative of the Rome area (Latium). Mineralogical composition, size distribution, optical properties and the surface radiative forcing efficiency (RFE) of dust types representing the compositional end members of this geological area have been addressed. A multi-disciplinary approach was used, based on chamber resuspension of raw materials and sampling of the PM10 fraction, to simulate field sampling at dust source, scanning electron microscopy/X-ray energy-dispersive microanalysis (SEM XEDS) of individual mineral particles, X-ray diffraction (XRD) analysis of bulk dust samples, building of number and volume size distribution (SD) from microanalysis data of mineral particles and fitting to a log-normal curve, and radiative transfer modelling (RTM) to retrieve optical properties and radiative effects of the compositional end-member dust samples. The mineralogical composition of Rome lithogenic PM10 varies between an end-member dominated by silicate minerals (from volcanics lithotypes), and one mostly composed of calcite (from travertine or limestones). Lithogenic PM10 with intermediate composition derives mainly from siliciclastic rocks or marlstones. Size and mineral species of PM10 particles of silicate-dominated dust types are tuned mainly by rock weathering and, to lesser extent, by debris formation or crystallization; chemical precipitation of CaCO3 plays a major role in calcite-dominated types. These differences are reflected in the diversity of volume distributions, either within dust types or mineral species. Differences are also observed between volume distributions of calcite from travertine (natural source; SD unimodal at 5 μm a.d.) and from road dust (anthropic source; SD bimodal at 3.8 and 1.8 μm a.d.). The volcanics and travertine dusts differently affect the single scattering albedo (SSA) and the asymmetry parameter (g) in the visible (VIS) and near-infrared (NIR) regions. The downward component of the bottom-of-atmosphere (BOA) solar irradiance simulated by RTM for an atmosphere where only volcanics (or only travertine dust) composes the aerosol, shows that the volcanics contribution to the solar irradiance differs significantly from that of travertine in the NIR region, while similar contributions are modelled in the VIS. The RFE (−293 W m−2 for volcanics and −139 W m−2 for travertine, at 50° solar zenith angle) shows that volcanics dust produces a stronger cooling effect at surface than travertine, as expected for more absorbing aerosols.