Particle Emission Rates Research Articles

Ultrafine particle emissions from essential-oil-based mosquito repellent products

Ultrafine particle (UFP) emissions from three essential-oil-based mosquito repellent products (lemon eucalyptus (LE), natural insects (NI), and bite shield (BS)) were tested in a 386 l chamber at a high air exchange rate of 24/h with filtered laboratory air. Total particle number concentration and size distribution were monitored by a condensation particle counter and a scanning mobility particle sizer, respectively. UFPs were emitted from all three products under indoor relevant ozone concentrations (~ 17 ppb). LE showed a nucleation burst followed by a relatively stable and continuous emission while the other two products (NI and BS) showed episodic emissions. The estimated maximum particle emission rate varied from 5.4 × 10(9) to 1.2 × 10(12) particles/min and was directly related to the dose of mosquito repellent used. These rates are comparable to those due to other indoor activities such as cooking and printing. The emission duration for LE lasted for 8-78 min depending on the dose applied while the emission duration for NI and BS lasted for 2-3 h. Certain essential-oil-based mosquito repellents can produce high concentrations of UFPs when applied, even at low ozone levels. Household and personal care products that contain essential oil may need to be tested at indoor relevant ozone levels to determine their potential to increase personal UFP exposures.

Characterization of the Particle Emissions from Diesel Transit Bus Equipping Diesel Particulate Filter with Fuel Burner

On-road particle emissions were tested in urban areas of Shanghai from a diesel bus equipping diesel particulate filter with fuel burner. EEPS 3090 particle analyzer was used for analyzing concentrations of particles in different diameters. In this paper, characterization of particles in soot loading and regeneration processes were identified, and particle reduction ability of DPF bus was analyzed. Result shows that, the averaged particle emission rate from DPF bus was degraded by 1 to 2 orders of magnitude during soot loading. Particle concentration distribution was transformed from nuclei-accumulated bi-modal pattern to uniformly multi-peaks patterns. In DPF regeneration process, particles of accumulated mode sized between 60.4nm and 107.5nm were decomposed and oxidized into fine nuclei particles of 29.4nm to 60.4nm, which increases total particle concentration. Reduction percentage of particle number per kilometer of DPF bus for soot loading and regeneration process reaches respectively 97% and 83.2% compared with normal diesel bus.

Comparison of particle mass and number emissions from a diesel transit bus across temporal and spatial scales

This study analyzes particle number and mass emission rates measured from the exhaust of a 2002 diesel transit bus in real-world driving conditions. The dynamics of the particle number and mass emission rates are examined at resolved temporal and spatial scales across an urban arterial, a rural arterial and a divided freeway. Time-based particle number and mass emission rates were highest on the freeway, but the distance-based particle emission rates of emission/km at “hot-spots” for exposure assessment for selected 50-m road segments occurred at intersections when the bus accelerated from a stop or traveled up high grades. Comparisons of particle mass and number emission rates between idling and acceleration indicate that unless the bus is extending idling for several minutes, public exposure to bus particle emissions near bus stops can be mainly attributed to accelerations. Generally, particle number and mass emissions rates are highly correlated both temporally and spatially. Some deviations occur because particle mass emissions are highly elevated during sustained fueling events such as traveling on high grades and during sustained accelerations, while particle number emissions are more sensitive to fuel and engine speed fluctuations.

Effect of relative humidity on the aerosolization and total inflammatory potential of fungal particles from dust-inoculated gypsum boards

The aim of this study was to investigate the effect of relative humidity (RH) on the aerosolization and total inflammatory potential (TIP) of microbial particles released from gypsum boards inoculated with dust samples from homes. After microbial colonization, the gypsum boards were incubated at either high or low RH. The aerosolized particles (0.54-19.8 μm), culturable fungi, β-glucan and the TIP of the aerosolized particles were quantified. Despite the colonization of several fungal groups, Penicillium dominated the aerosolized fraction. Higher emission rates of particles and culturable fungi were found from low RH compared with high RH in both the inhalable and particulate matter <1 μm (PM1 ) fractions, and the TIP was accordingly higher. However, for the aerosolized fractions, the TIP or concentration β-glucan relative to the number of fungi or particles present was higher from high RH compared with low RH. Despite the low number of culturable fungi in PM1 , this fraction showed a high TIP, and the concentration of β-glucan correlated strongly with the TIP of this fraction. The individual particles of the aerosolized PM1 fraction were more inflammatory than the larger particles of the inhalable fraction, and β-glucan may be an important contributor to the inflammatory potential of the aerosolized particles.

A PEMS study of the emissions of gaseous pollutants and ultrafine particles from gasoline- and diesel-fueled vehicles

On-road emission measurements of gasoline- and diesel-fueled vehicles were conducted by a portable emission measurement system (PEMS) in Shanghai, China. Horiba OBS 2200 and TSI EEPS 3090 were employed to detect gaseous and ultrafine particle emissions during the tests. The driving-based emission factors of gaseous pollutants and particle mass and number were obtained on various road types. The average NOx emission factors of the diesel bus, diesel car, and gasoline car were 8.86, 0.68, and 0.17 g km−1, all of which were in excess of their emission limits. The particle number emission factors were 7.06 × 1014, 6.08 × 1014, and 1.57 × 1014 km−1, generally higher than the results for similar vehicle types reported in the previous studies. The size distributions of the particles emitted from the diesel vehicles were mainly concentrated in the accumulation mode, while those emitted from the gasoline car were mainly distributed in the nucleation mode. Both gaseous and particle emission rates exhibit significant correlations with the change in vehicle speed and power demand. The lowest emission rates for each vehicle type were produced during idling. The highest emission rates for each vehicle type were generally found in high-VSP bins. The particle number emission rates of the gasoline car show the strongest growth trend with increasing VSP and speed. The particle number emission for the gasoline car increased by 3 orders of magnitude from idling to the highest VSP and driving speed conditions. High engine power caused by aggressive driving or heavy loads is the main contributor to high emissions for these vehicles in real-world situations.

Fine and coarse particle mass concentrations and emission rates in the workplace of a detergent industry

Aerosol mass concentration (PM10, PM2.5) measurements were conducted in the workplace of a detergent industry for two time periods during July 2005 and January 2006, using two portable real-time photometric monitors. The results showed increased mass concentrations both for PM10 and PM2.5 particles during the detergent production periods. The differences in the concentrations of the PM10 and PM2.5 particles were used to determine the corresponding mass concentrations of coarse particles and these values were then used to evaluate the diurnal variation both for fine and coarse particles. An indoor mass balance model was applied to estimate the aerosol mass emission rates, as well as the particle loss rates due to all removal processes. A good agreement was obtained between the model predictions and the measurements. The indoor model can be used in conjunction with experimental measurements for the evaluation of aerosol mass concentrations in industrial sites.

Numerical modelling of flow structures over an industrial site: effect of the surrounding buildings on dust emissions

In this paper, three-dimensional numerical simulations are used to simulate the wind flow structure over coal stockpiles of a real configuration of a power plant. Two configurations are tested for various wind directions: the first one without representing the buildings and the second one with the surrounding buildings in the calculation domain. The wind flow properties over the full site and near the stockpile surfaces are analyzed in order to understand the dust emission mechanisms over the various tested configurations. The emission factor formulation, proposed by the EPA to quantify fugitive dust emissions from a stockpile, is used to check the particle emission rate for each considered configuration using the velocity fields given by the simulations. The analysis of the results from the two tested configurations shows by evidence that the topography of the industrial site exerts large perturbations on the flow structure over the site. This work shows that previous studies carried out without taking into consideration the topography of the site probably lead to an inaccurate estimation of the fugitive dust emissions. This study highlights the necessity to take into account the presence of surrounding buildings to estimate and quantify the particle emission rate on stockpiles. The study reported in this paper improves the understanding of fugitive dust emissions on industrial sites and in mining zones. These results will allow a more accurate and relevant evaluation of fugitive dust emissions from open storage systems on industrial sites and a better evaluation of its environmental impacts.

Emissions from Irish domestic fireplaces and their impact on indoor air quality when used as supplementary heating source

A field study on the impact of fireplace on the indoor air quality was carried out between 2004 and 2006, where two main contaminants, CO and particulate matters, were investigated in twenty seven randomly selected Irish houses. The results show that while the physical environment has been improved by increasing the room air and radiant temperature, indoor air quality is significantly decreased when fireplace is used as additional heating source to the central heating. The operation of fireplace increased transient concentrations of CO and airborne particle to several times higher than the normal house average level. Statistical analysis showed significant difference of the average PM10 concentration between house groups with and without using fireplace. However fireplace did not demonstrate a significant influence on average CO level from our samples. When comparisons were made between houses with various emission sources, i.e. fireplace, smoking and open fire gas cooking, and houses free of the above sources, smoking and open fire gas cookers were proved to be other major sources of particles and CO. Particularly when they exist at the same time with fireplace, significant elevation of CO and airborne particle levels is observed in analysis. Cumulative probability analysis in some houses revealed high percentage of time exceeding health guidelines which indicated the potential health risk in these houses. Mass balance equation was employed to estimate particle emission rates from fireplace, namely 0.66 mg min-1 (PM10) and 0.20 mg min-1 (PM2.5) respectively in terms of mass concentration. Emission rates on particle numbers were also estimated despite the relatively smaller sample. Gas fuel fireplaces tended to emit fewer particles both in mass and in number comparing to fireplaces using solid fuels.

Determination of dynamic intake fraction of cooking-generated particles in the kitchen

This paper attempts to determine the individual intake fraction of particles generated from a simplified cooking process of edible oil heating in the kitchen. First, two separate sets of experiments, utilizing real-time Malvern particle sizer and TSI aerosol monitor, respectively, are combined to obtain the size-dependent emission rate of fume particles from the cooking process. Second, a drift flux model for particle dispersion, getting particle source-releasing conditions from the experimental data, is applied to predict the dynamic concentration in the kitchen. Third, size-dependent dynamic intake fraction of the particles by an individual in the kitchen, based on a breathing model defined, is determined from the predicted particle concentrations. It is found from the case studies that the inhaled particle concentration is highly attributed to the air distribution under different ventilation conditions of the kitchen space, even if both the ventilation rate and final capture efficiency of the exhaust system are the same. It is confirmed that different air inflow results in even different magnitude of intake fraction, ranged from ∼10−3 to ∼10−5. Lower intake fraction is observed under the open door conditions because inflow from the lower-level of the door produces some effect as the displacement ventilation. Results also show that size distribution of the inhaled mass is similar to that at the source, and the dynamic intake fraction is little sensitized to the particle size, due to the short-time and short-distance particle dynamics during the cooking process. The present work quantifies the attributed fraction of cooking-generated particles taken in by exposed individual through integrating the experimental and numerical methods. It helps to evaluate the indoor air quality and understand the health risk due to cooking activity in the kitchen space.

Half-lives of 221Fr, 217At, 213Bi, 213Po and 209Pb from the 225Ac decay series

The half-lives of 221Fr, 217At, 213Bi, 213Po, and 209Pb were measured by means of an ion-implanted planar Si detector for alpha and beta particles emitted from weak 225Ac sources or from recoil sources, which were placed in a quasi-2π counting geometry. Recoil sources were prepared by collecting atoms from an open 225Ac source onto a glass substrate. The 221Fr and 213Bi half-lives were determined by following the alpha particle emission rate of recoil sources as a function of time. Similarly, the 209Pb half-life was determined from the beta particle count rate. The shorter half-lives of 217At and 213Po were deduced from delayed coincidence measurements on weak 225Ac sources using digital data acquisition in list mode. The resulting values: T1/2(221Fr)=4.806 (6) min, T1/2(217At)=32.8 (3)ms, T1/2(213Bi)=45.62 (6)min, T1/2(213Po)=3.708 (8)μs, and T1/2(209Pb)=3.232 (5)h were in agreement only with the best literature data.

Characterization of decay and emission rates of ultrafine particles in indoor ice rink

The purposes of this study were to determine indoor ultrafine particle (UFP, diameter <100 nm) levels in ice rinks and to characterize UFP decay and emission rates. All 15 public ice rinks in Seoul were investigated for UFP and carbon monoxide (CO) concentrations. Three ice rinks did not show peaks in UFP concentrations, and one ice rink used two resurfacers simultaneously. High peaks of UFP and CO concentrations were observed when the resurfacer was operated. The average air change rate in the 11 ice rinks was 0.21 ± 0.13/h. The average decay rates of UFP number concentrations measured by the P-Trak and DiSCmini were 0.54 ± 0.21/h and 0.85 ± 0.34/h, respectively. The average decay rate of UFP surface area concentration was 0.33 ± 0.15/h. The average emission rates of UFP number concentrations measured by P-Trak and DiSCmini were 1.2 × 10(14) ± 6.5 × 10(13) particles/min and 3.3 × 10(14) ± 2.4 × 10(14) particles/min, respectively. The average emission rate of UFP surface area concentration was 3.1 × 10(11) ± 2.0 × 10(11) μm(2)/min. UFP emission rate was associated with resurfacer age. DiSCmini measured higher decay and emission rates than P-Trak due to their different measuring mechanisms and size ranges.

Measuring the Short-Term Emission Rates of Particles in the “Personal Cloud” with Different Clothes and Activity Intensities in a Sealed Chamber

A series of measurements were conducted to determine the short-term emission rates of particles in the “personal cloud” (i.e., particle emission from a clothed human body) in a sealed chamber. By recording the concentration of particles of different sizes during a period of time in the chamber, curves monitoring the evolution of particle concentration caused by emissions from a clothed human body were obtained. Based on the measured evolution of particle concentrations and deposition rates, the emission rates of particles from a clothed human body were estimated with a physical model. Generally speaking, the size-dependent emission rates of particles from a human body wearing a clean room smock were the lowest, while those from one wearing a cotton suit were the highest among the forms of clothing examined this work. Furthermore, the emission rates of particles from a clothed human body were positively correlated with the intensity of human activity. In addition, activities tended to have a more significant impact on the emission rates with regard to coarse rather than fine particles. The experimental data for the emission rates of particles from a clothed human body provided in this study may be used in further particle exposure assessments in certain indoor environments, such as clean rooms and aircraft cabins, as a valid input parameter.

Determination of Size-Dependent Source Emission Rate of Cooking-Generated Aerosol Particles at the Oil-Heating Stage in an Experimental Kitchen

ABSTRACTCooking-generated particles represent one major indoor particulate pollutant that significantly affect indoor air quality as well as pose a risk to human health. Prediction of the spatial-temporal distribution of fume particles and individual inhalation exposure is highly dependent upon the source characteristics. This study aims to determine the emission rate of cooking-generated particles in the range from 0.1 to 10 μm, because this size is of most concern when considering indoor particle dynamics. The mass concentration and volume-based size distribution of particles in the range from 0.1 to 10 μm are measured under controlled conditions in a laboratory kitchen. Based on a mass balance model, the total emission rates of PM2.5 and PM10 are determined using the concentration decay rate derived from the measured concentration plus its changing curve with time. The size-dependent emission rate is further obtained by multiplying the total emission rate by the particle volume distribution. It is found that source strengths are highly sensitive to the oil type, whilst both the volume-distribution patterns and decay rate values exhibit less difference among the six types of vegetable oil examined in this work. The relative variance of source rate determined at time spans from 15 min to 2 h is less than 5.5%, and thus a short measuring period of 15 min is sufficient to derive a reliable emission rate. The results also show that the volume frequency of particles in the size range from 1.0 to 4.0 μm accounts for nearly 100% of the mass of PM10 in the oil-heating experiments. The size range and the associated size-based emission rates derived in this study can be applied as the source characteristics for further studies of indoor particle dynamics.

Modeling multi-scale aerosol dynamics and micro-environmental air quality near a large highway intersection using the CTAG model

A new methodology, referred to as the multi-scale structure, integrates “tailpipe-to-road” (i.e., on-road domain) and “road-to-ambient” (i.e., near-road domain) simulations to elucidate the environmental impacts of particulate emissions from traffic sources. The multi-scale structure is implemented in the CTAG model to 1) generate process-based on-road emission rates of ultrafine particles (UFPs) by explicitly simulating the effects of exhaust properties, traffic conditions, and meteorological conditions and 2) to characterize the impacts of traffic-related emissions on micro-environmental air quality near a highway intersection in Rochester, NY. The performance of CTAG, evaluated against with the field measurements, shows adequate agreement in capturing the dispersion of carbon monoxide (CO) and the number concentrations of UFPs in the near road micro-environment. As a proof-of-concept case study, we also apply CTAG to separate the relative impacts of the shutdown of a large coal-fired power plant (CFPP) and the adoption of the ultra-low-sulfur diesel (ULSD) on UFP concentrations in the intersection micro-environment. Although CTAG is still computationally expensive compared to the widely-used parameterized dispersion models, it has the potential to advance our capability to predict the impacts of UFP emissions and spatial/temporal variations of air pollutants in complex environments. Furthermore, for the on-road simulations, CTAG can serve as a process-based emission model; Combining the on-road and near-road simulations, CTAG becomes a "plume-in-grid" model for mobile emissions. The processed emission profiles can potentially improve regional air quality and climate predictions accordingly.

Physical characteristics of nanoparticles emitted during drilling of silica based polyamide 6 nanocomposites

During the past decade, polymer nanocomposites have emerged as a novel and rapidly developing class of materials and attracted considerable investment in research and development worldwide. However, there is currently a lack of information available in the literature on the emission rates of particles from these material. In this study, real-time characterization of the size distribution and number concentration of sub-micrometer-sized particles (5.6-512 nm) emitted from polyamide 6 nanocomposites during mechanical drilling was made. For the first time, four different silica based filler of commonly use were assessed. Further, the respective emission rates were determined based on the particle population and the time. The measurements showed that the particle emission rates ranged from 1.16E+07 (min−1) to 1.03E+09 (min−1) and that the peak diameters varied from 29.6 to 75.1 nm. Airborne particles in the nanometer range (11.1-46.8 nm), in the ultrafine range (51.3-101.1 nm) and in the accumulation mode range (111.9-521 nm) accounted for 34.1% to 76.6%, 8.3% to 47% and 4.1% to 24.2% of the total emission rates, respectively, depending on the type of filler. Additionally, deposited particles were sampled and characterized, to explore any possible correlation between deposited and airborne particles. The result clearly showed that with increasing airborne particle concentration the deposit particle concentration decreased and vice verse.

Emission Estimates of Particulate PAHs from Biomass Fuels Used in Delhi, India

ABSTRACT The emission factors for particulate-phase polycyclic aromatic hydrocarbons (PAHs) were evaluated for various biomass fuels (fuelwood, dung cakes, and agricultural residue) that are being commonly used in Delhi as a source of energy. Emission factors of total particulate PAHs varied from 35.9 ± 1.9 to 59.7 ± 4.4 mg/kg. Higher levels of total PAHs and particulate matter (PM) were found from dung cakes as compared to fuelwood and agricultural residue. The emission factors for PM from dung cake, fuelwood, and agricultural residue are 25 ± 8, 15 ± 3.2, and 12.1 ± 9.4 g/kg, respectively. The total PAH emissions showed an increase with high particulate matter emission rates and lower combustion efficiency. Fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, and benzo[a]pyrene constituted the major fraction of PAH emissions from all biomass fuels. The annual budget estimates (total emissions per year) for PAHs and PM from biomass fuels used in Delhi are 30.5 ± 2.3 Mg (Megagrams) and 11.6 ± 4.4 Gg (Gigagrams), respectively. An attempt has also been made to evaluate the preliminary budget estimates of PAHs and PM emitted from the use of biomass fuels as a source of energy in India by using the emission factors obtained in the present study.

Monitoring charged particle and ion emissions from a laser printer

While the emission rate of ultrafine particles has been measured and quantified, there is very little information on the emission rates of ions and charged particles from laser printers. This paper describes a methodology that can be adopted for measuring the surface charge density on printed paper and the ion and charged particle emissions during operation of a high-emitting laser printer and shows how emission rates of ultrafine particles, ions and charged particles may be quantified using a controlled experiment within a closed chamber. ► Little information on emission rates of ions/charged particles from laser printers. ► Describes methodology for measuring surface charge density on printed paper. ► Also for measuring ion/charged particle emissions during operation.

LIGHT-PARTICLE EMISSION FROM FISSIONING HOT ROTATING NUCLEI

The decay process of hot and rotating compound nuclei is studied. In particular the competition between fission and n, p and α-particle emission is discussed. The nuclear fission process is described by a Langevin equation coupled to Master equations for particle evaporation. Light particle emission rates obtained with the Weisskopf theory and the semiclassical phase-space distribution-function approach are compared. Coulomb barriers for the emission of charged particles are studied.

PM2.5and ultrafine particles emitted during heating of commercial cooking oils

Seven commercial cooking oils were investigated to determine the PM(2.5) mass and ultrafine particle (UFP) emission rates and emission fluxes (rates per area). The results of this study showed that at 197°C soybean, safflower, canola, and peanut oils produced lower PM(2.5) emission fluxes (6.1 × 10(5), 3.0 × 10(5), 5.4 × 10(5), and 3.9 × 10(5) μg/min/m(2), respectively) than corn, coconut, and olive oils (2.7 × 10(6), 2.9 × 10(6), and 5.7 × 10(6) μg/min/m(2), respectively). Similarly, the total particle number flux at 197°C was lower for soybean, safflower, and canola oils (3.5 × 10(13), 8.6 × 10(13), and 1.0 × 10(14) #/min/m(2), respectively) than the corn, coconut, olive, and peanut oils (2.4 × 10(14), 1.4 × 10(14), 1.7 × 10(14), and 3.8 × 10(14) #/min/m(2), respectively). In general, oils with a higher smoke temperature resulted in lower particle concentrations over the measured temperature range (131-197°C). The percentage of UFP (particle diameter D(p) 10-100 nm) to total particles (D(p) 10-500 nm) ranged from 76 to 99% for this temperature range. Particles below 10 nm in diameter were not measured. The particle number size distribution showed a polydisperse behavior with major mode sizes ranging from 25 nm (for peanut oil) to 82 nm (for soybean oil) at an oil temperature of 197°C. The study presents particle number and mass concentrations, size distributions, emission rates, and emission fluxes from heating common cooking oils. The emission rates and emission fluxes can be used as inputs to models for indirect exposure analysis studies. The study may also be used to provide guidance on choosing oils that result in lower emission rates when heated.

Numerical simulation for a wind dust event in the US/Mexico border region

Soil-derived dust represents one of the major components of the natural atmospheric aerosols. Arid and semiarid areas with unpaved and non-vegetated land cover are particularly vulnerable to windblown dust, which results in high particulate matter pollution. To understand, predict, and mitigate the impact of dust aerosol on air quality and climate, it is necessary to parameterize the emission rate of dust particles from the wind erosion processes accurately. However, windblown dust emission is poorly represented in existing air quality models. In this paper, a windblown dust emission model has been developed based on a parameterization of threshold wind friction velocity depending on the roughness of surface, vegetation type, soil type, soil moisture content, and on the size distribution of aerosols. The proposed dust model incorporates into a region air quality modeling system to simulate a North American dust storm episode occurring near the border of southwestern USA and northwestern region of Mexico on 23 February 2007. It is shown that the implementation of a windblown dust model in an air quality model can significantly improve the model capability for capturing the dust episode. The simulation of the model is in good agreement with the evolution of dust distribution. The modeled dust spatial patterns matched dust cloud patterns appearing on satellite images. Implementation of the windblown dust model successfully captured the time of peak particulate matter (PM) concentrations for both PM10 and PM2.5, as well as the peak value of the PM2.5 concentration. The modeled results clearly demonstrate an improved ability to predict PM events by applying the windblown dust emission scheme.