Gas Chromatographic Analysis of Ambient Halogenated Compounds

Abstract

Fugitive dust emission from limestone extraction areas is a significant pollution source. The cracking operation in limestone extraction areas easily causes high total suspended particulate (TSP) concentrations in the atmosphere, occasionally exceeding the 1-hr national emission standard of Taiwan (500 μg/m³). The concentration and size distribution were measured at different distances (0.05–15 km) in the extraction areas. The highest hourly concentrations of TSP, PM₁₀ (suspended particulate matter [PM] smaller than 10 μm), and PM_2.5 (suspended PM smaller than 2.5 μm) are 1111, 825, and 236 μg/m³, respectively, during the cracking process. Measurement results obtained from the Micro-Orifice Uniform Deposit Impactor indicated that the mass median aerodynamic diameter is ～0.7 μm, with the geometric standard deviation exceeding 7. In addition, the emission factors are 0.143 and 0.211 kg/t for both vertical well and stair extraction operations, respectively. Experimental results demonstrate that the corresponding TSP control efficiencies for spraying water, planting grass, setting short walls, paving gravel roads, and establishing vertical well transportation are ～55, 50, 44, 22, and 30%, respectively. Furthermore, the PM₁₀ control efficiencies are ～45, 41, 54, 35, and 30%, respectively, whereas the PM_2.5 control efficiencies are roughly 23, 31, 15, 11, and 10%, individually.     

Determination of Levoglucosan in Atmospheric Fine Particulate Matter

Abstract

A microanalytical method suitable for the quantitative determination of the sugar anhydride levoglucosan in low-volume samples of atmospheric fine particulate matter (PM) has been developed and validated. The method incorporates two sugar anhydrides as quality control standards. The recovery standard sedoheptulosan (2,7-anhydro-β-D-altro-heptulopyranose) in 20 μL solvent is added onto samples of the atmospheric fine PM and aged for 1 hr before ultrasonic extraction with ethylacetate/ triethylamine. The extract is reduced in volume, an internal standard is added (1,5-anhydro-D-mannitol), and a portion of the extract is derivatized with 10% by volume N-trimethylsilylimidazole. The derivatized extract is analyzed by gas chromatography/mass spectrometry (GC/MS). The recovery of levoglucosan using this procedure was 69 ± 6% from five filters amended with 2 μg levoglu-cosan, and the reproducibility of the assay is 9%. The limit of detection is ～0.1 μg/mL, which is equivalent to ～3.5 ng/m³ for a 10 L/min sampler or ～8.7 ng/m³ for a 4 L/min personal sampler (assuming 24-hr integrated samples). We demonstrated that levoglucosan concentrations in collocated samples (expressed as ng/m³) were identical irrespective of whether samples were collected by PM with aerodynamic diameter ≤2.5 μm or PM with aerodynamic diameter ≤10 μm impactors. It was also demonstrated that X-ray fluorescence analysis of samples of atmospheric PM, before levoglucosan determinations, did not alter the levels of levoglucosan.     

Size and Composition Distributions of Particulate Matter Emissions: Part 1—Light-Duty Gasoline Vehicles

Abstract

Size-resolved particulate matter (PM) emitted from light-duty gasoline vehicles (LDGVs) was characterized using filter-based samplers, cascade impactors, and scanning mobility particle size measurements in the summer 2002. Thirty LDGVs, with different engine and emissions control technologies (model years 1965–2003; odometer readings 1264–207,104 mi), were tested on a chassis dynamometer using the federal test procedure (FTP), the unified cycle (UC), and the correction cycle (CC). LDGV PM emissions were strongly correlated with vehicle age and emissions control technology. The oldest models had average ultrafine PM_0.1 (0.056- to 0.1-μm aerodynamic diameter) and fine PM_1.8 (≤1.8-μm aerodynamic diame ter) emission rates of 9.6 mg/km and 213 mg/km, respectively. The newest vehicles had PM_0.1 and PM_1.8 emis sions of 51 μg/km and 371 μg/km, respectively. Light duty trucks and sport utility vehicles had PM_0.1 and PM_1.8 emissions nearly double the corresponding emission rates from passenger cars. Higher PM emissions were associated with cold starts and hard accelerations. The FTP driving cycle produced the lowest emissions, followed by the UC and the CC. PM mass distributions peaked between 0.1-and 0.18-μm particle diameter for all vehicles except those emitting visible smoke, which peaked between 0.18 and 0.32 μm. The majority of the PM was composed of carbonaceous material, with only trace amounts of water-soluble ions. Elemental carbon (EC) and organic matter (OM) had similar size distributions, but the EC/OM ratio in LDGV exhaust particles was a strong function of the adopted emissions control technology and of vehicle maintenance. Exhaust from LDGV classes with lower PM emissions generally had higher EC/OM ratios. LDGVs adopting newer technologies were characterized by the highest EC/OM ratios, whereas OM dominated PM emissions from older vehicles. Driving cycles with cold starts and hard accelerations produced higher EC/OM ratios in ultrafine particles.     

Characterization of air manganese exposure estimates for residents in two Ohio towns

This study was conducted to derive receptor-specific outdoor exposure concentrations of total suspended particulate (TSP) and respirable (d_ae ≤ 10 µm) air manganese (air-Mn) for East Liverpool and Marietta (Ohio) in the absence of facility emissions data, but where long-term air measurements were available. Our “site-surface area emissions method” used U.S. Environmental Protection Agency’s (EPA) AERMOD (AMS/EPA Regulatory Model) dispersion model and air measurement data to estimate concentrations for residential receptor sites in the two communities. Modeled concentrations were used to create ratios between receptor points and calibrated using measured data from local air monitoring stations. Estimated outdoor air-Mn concentrations were derived for individual study subjects in both towns. The mean estimated long-term air-Mn exposure levels for total suspended particulate were 0.35 μg/m³ (geometric mean [GM]) and 0.88 μg/m³ (arithmetic mean [AM]) in East Liverpool (range: 0.014–6.32 μg/m³) and 0.17 μg/m³ (GM) and 0.21 μg/m³ (AM) in Marietta (range: 0.03–1.61 μg/m³). Modeled results compared well with averaged ambient air measurements from local air monitoring stations. Exposure to respirable Mn particulate matter (PM₁₀; PM <10 μm) was higher in Marietta residents.

Implications: Few available studies evaluate long-term health outcomes from inhalational manganese (Mn) exposure in residential populations, due in part to challenges in measuring individual exposures. Local long-term air measurements provide the means to calibrate models used in estimating long-term exposures. Furthermore, this combination of modeling and ambient air sampling can be used to derive receptor-specific exposure estimates even in the absence of source emissions data for use in human health outcome studies.     

Measurements of Sulfur Oxides,Nitrogen Oxides,Haze and Fine Particles at a Rural Site on the Atlantic Coast

During August, 1982 and January and February, 1983, General Motors Research Laboratories operated air monitoring sites on the Atlantic Coast near Lewes, Delaware and 1250 km to the east on the southwest coast of Bermuda. The overall purpose of this project was to study the transformations of the principal acid precipitation precursors, NO _x and SO _x species, as they transport under conditions not complicated by emissions from local sources. In this paper, the measurements of gas and particulate species from Lewes are described and the composition and sources of sulfate aerosol, which is the most important haze-producing species, are investigated.

On the average, the total suspended particulate (TSP) concentration was 27.9 μg/m³ while the PM₁₀ (mass of particles with a diameter less than or equal to 10 μm) concentration was 22.0 μg/m³ or 79 percent of the TSP. The PM₁₀ consisted of 6.1 μg/m³ of coarse particles (CPM, diameter = 2.5 ? 10μm) and 15.9 μg/m³ of fine particles (FPM, diameter < 2.5 μm).

On a mass basis the most important constituents of the fine particulate fraction were sulfate compounds, 50 percent, and organic compounds, 30 percent. The mean light extinction coefficient corresponds to a visual range of 18-20 km. Most of the extinction can be attributed to the sulfate (60 percent) and organic carbon (13 percent). Particle size measurements show that the mass median aerodynamic diameter for both species is 0.43 μm. This is a typical size for a hydrated sulfate aerosol. For carbon, however, this is a larger size than previously reported and results in a more efficient light scattering aerosol. Principal component analyses indicate that coal combustion emissions from the midwestern U.S. are the most significant source of sulfate in Lewes during the summer and winter.     

Aerosol Aerodynamic Size Conventions For Inertia! Sampler Calibration

The body of information presented in this paper is directed to investigators using inertial samplers for precise and accurate studies of respirable aerosols. The conventions commonly used for aerodynamic size for aerosol particles are discussed including the definition popularized by the "Task Group on Lung Dynamics" of the ICRP, and the "Lovelace" definition. To emphasize the distinction, the Task Group definition (unit density sphere equivalent) is called the aerodynamic equivalent diameter, D_ae, and the Lovelace definition (characteristic expression based upon viscous resistance) is called the aerodynamic resistance diameter, D_ar. The implications and efficacy of these conventions are related to procedures for calibration of cascade impactors, cyclones, and spiral centrifuges. The calibration of a spiral centrifuge at different altitudes is used as an example of the potential problems associated with the use of the different conventions for describing aerodynamic size. The aerodynamic resistance diameter is recommended for calibration of inertial samplers to be used to collect aerosols in the respirable size range.     

A 10 μm Outpoint Size Selective Inlet for Hi-Vol Samplers

A Two-stage Size Selective Inlet for use with hi-vol samplers was designed and tested. The inlet, which operates at a flow rate of 1.13 m³/min, is shown to have a cutpoint of 9.8 μm and a fractionation curve slope of 1.45. The cutpoint is well within the EPA suggested limits of 10 ± 1 μm. Fractionation is not affected by wind speed over the test range of 2-24 km/h.

Re-entrainment or bounce of solid particles is not of consequence. The difference in penetration of 20 μm aerodynamic diameter glass beads and liquid aerosols is less than 1% at all wind speeds.     

Low Flow Rate Sharp Cut Impactors for Indoor Air Sampling: Design and Calibration

Two single round nozzle impactors have been developed for use in Harvard’s indoor air pollution health study. Both impactors operate at flow rates of 4 L/m and are nearly identical, differing only in their cut sizes of 2.5 μm and 10 μm aerodynamic diameters. Two identical cascaded stages of the same cut size are used to obtain sharp cut-off characteristics. The particles are deposited on impaction plates made of oil impregnated, porous material to reduce particle bounce and are discarded. Only the particles collected on the afterfilter are analyzed. Special care has been taken to collect the particles uniformly on the afterfilter to aid in particle analysis.

The jmpactors were calibrated with a vibrating orifice monodisperse aerosol generator. However, due to the sharp cut of the impactors, doublets and triplets in the calibration aerosols, even in small quantities, gave erroneous calibration curves. Therefore, the number of doublets and triplets in the challenging aerosols were measured and appropriate corrections made to the calibration curves.     

Outdoor fine and ultrafine particle measurements at six bus stops with smoking on two California arterial highways—Results of a pilot study

As indoor smoking bans have become widely adopted, some U.S. communities are considering restricting smoking outdoors, creating a need for measurements of air pollution near smokers outdoors. Personal exposure experiments were conducted with four to five participants at six sidewalk bus stops located 1.5–3.3 m from the curb of two heavily traveled California arterial highways with 3300–5100 vehicles per hour. At each bus stop, a smoker in the group smoked a cigarette. Gravimetrically calibrated continuous monitors were used to measure fine particle concentrations (aerodynamic diameter ≤2.5 µm; PM_2.5) in the breathing zones (within 0.2 m from the nose and mouth) of each participant. At each bus stop, ultrafine particles (UFP), wind speed, temperature, relative humidity, and traffic counts were also measured. For 13 cigarette experiments, the mean PM_2.5 personal exposure of the nonsmoker seated 0.5 m from the smoker during a 5-min cigarette ranged from 15 to 153 µg/m³. Of four persons seated on the bench, the smoker received the highest PM_2.5 breathing-zone exposure of 192 µg/m³. There was a strong proximity effect: nonsmokers at distances 0.5, 1.0, and 1.5 m from the smoker received mean PM_2.5 personal exposures of 59, 40, and 28 µg/m³, respectively, compared with a background level of 1.7 µg/m³. Like the PM_2.5 concentrations, UFP concentrations measured 0.5 m from the smoker increased abruptly when a cigarette started and decreased when the cigarette ended, averaging 44,500 particles/cm³ compared with the background level of 7200 particles/cm³. During nonsmoking periods, the UFP background concentrations showed occasional peaks due to traffic, whereas PM_2.5 background concentrations were extremely low. The results indicate that a single cigarette smoked outdoors at a bus stop can cause PM_2.5 and UFP concentrations near the smoker that are 16–35 and 6.2 times, respectively, higher than the background concentrations due to cars and trucks on an adjacent arterial highway.

Implications: Rules banning smoking indoors have been widely adopted in the United States and in many countries. Some communities are considering smoking bans that would apply to outdoor locations. Although many measurements are available of pollutant concentrations from secondhand smoke at indoor locations, few measurements are available of exposure to secondhand smoke outdoors. This study provides new data on exposure to fine and ultrafine particles from secondhand smoke near a smoker outdoors. The levels are compared with the exposure measured next to a highway. The findings are important for policies that might be developed for reducing exposure to secondhand smoke outdoors.     

Impact of the Saharan dust outbreaks on the ambient levels of total suspended particles (TSP) in the marine boundary layer (MBL) of the Subtropical Eastern North Atlantic Ocean

Six years (1998–2003) of measurements of ambient air concentrations of total suspended particulate (TSP) measured at a rural background monitoring station in Tenerife (Canary Islands), the El Río station (ER, 28°08′35″N, 16°39′20″W, 500 m a.s.l.) were studied. African dust outbreaks were objectively identified using a new quantitative tool, called the African Index. This index indicates the percentage of time that an air mass remained over an African region at one of three possible height intervals of the lower troposphere. After identifying these episodes, a study of the background TSP levels at the ER station and of direct and indirect (those which cause vertical deposition of dust) African air mass intrusion impacts was performed. Taking into account both direct and indirect episodes, a total of 322 days of African dust intrusion were objectively identified (a mean of 54 episodes per year) in the period 1998–2003, some of them caused by “transition episodes” or “return African air masses”. A subjective method confirmed that 256 of these days were caused by direct impacts of African dust on the ER station. A mean TSP value of 21.6 μg m⁻³ was found at the station during this period. All the episodes occurred when the TSP concentration was >28.5 μg m⁻³. The TSP background (14 μg m⁻³) can be assumed to be representative of the MBL of the Eastern North Atlantic subtropical region. The highest number of dust gravitational settlement (or indirect) episodes occurs in summer, but the highest contribution of these episodes to the TSP levels is in March with a monthly mean TSP contribution of up to 30.5 μg m⁻³.     

Concentration,size, and density of total suspended particulates at the air exhaust of concentrated animal feeding operations

Total suspended particulate (TSP) samples were seasonally collected at the air exhaust of 15 commercial concentrated animal feeding operations (CAFOs; including swine finishing, swine farrowing, swine gestation, laying hen, and tom turkey) in the U.S. Midwest. The measured TSP concentrations ranged from 0.38 ± 0.04 mg m^?3 (swine gestation in summer) to 10.9 ± 3.9 mg m^?3 (tom turkey in winter) and were significantly affected by animal species, housing facility type, feeder type (dry or wet), and season. The average particle size of collected TSP samples in terms of mass median equivalent spherical diameter ranged from 14.8 ± 0.5 µm (swine finishing in winter) to 30.5 ± 2.0 µm (tom turkey in summer) and showed a significant seasonal effect. This finding affirmed that particulate matter (PM) released from CAFOs contains a significant portion of large particles. The measured particle size distribution (PSD) and the density of deposited particles (on average 1.65 ± 0.13 g cm^?3) were used to estimate the mass fractions of PM₁₀ and PM_2.5 (PM ≤10 and ≤2.5 μm, respectively) in the collected TSP. The results showed that the PM₁₀ fractions ranged from 12.7 ± 5.1% (tom turkey) to 21.1 ± 3.2% (swine finishing), whereas the PM_2.5 fractions ranged from 3.4 ± 1.9% (tom turkey) to 5.7 ± 3.2% (swine finishing) and were smaller than 9.0% at all visited CAFOs. This study applied a filter-based method for PSD measurement and deposited particles as a surrogate to estimate the TSP’s particle density. The limitations, along with the assumptions adopted during the calculation of PM mass fractions, must be recognized when comparing the findings to other studies.

Implications: The concentration, size, and density of TSP samples varied greatly with animal species, housing facility type, feeder type, and season, suggesting that PM emission data derived from limited measurements may not be readily applied to estimate the overall emission from concentrated animal feeding operations (CAFOs). This study also affirmed that particles released from CAFOs is of relatively high density (~1.65 g cm^?3) and with diameter mostly larger than 10 µm, indicating that regular PM abatement devices, such as cyclones, fabric filters, or even a simple downward-facing exhaust duct, may be employed to mitigate the TSP emission with acceptable efficiency.     

Spatial variation of mass concentration of roadside suspended particulate matter in metropolitan Hong Kong

This study conducted roadside particulate sampling to measure the total suspended particulate (TSP), PM₁₀ (particles <10 μm in aerodynamic diameter) and PM_2.5 (particles <2.5 μm in aerodynamic diameter) mass concentration in 11 urbanized and densely populated districts in Hong Kong. One hundred and thirty-three samples were obtained to measure the mass concentrations of TSP, PM₁₀ and PM_2.5. According to these results, the TSP, PM₁₀ and PM_2.5 mass concentrations varied from 94.85 to 301.63 μg m⁻³, 67.67 to 142.68 μg m⁻³ and 50.01 to 125.12 μg m⁻³, respectively. The PM_2.5/PM₁₀ ratio of all samples was 0.82 which ranged from 0.62 to 0.95. The PM levels and PM ratios in metropolitan Hong Kong significantly fluctuated from site-to-site and over time. The PM_2.5 mass concentration in different districts corresponding to urban industrial, new town, urban residential and urban commercial were 77.64, 87.50, 106.96 and 88.54 μg m⁻³, respectively. The PM_2.5 level is high in Hong Kong, and for individual sampling, more than 60% daily measurements exceeded the NAAQS. The mass fraction of PM_2.5 in PM₁₀ and TSP is relatively high when compared with overseas studies.     

Fine and Ultrafine Emission Dynamics from a Ferrous Foundry Cupola Furnace

Abstract

Aerosol size distributions from ferrous foundry cupola furnaces vary depending on semicontinuous process dynamics, time along the tap-to-tap cycle, dilution ratio, and the physical and chemical nature of the charge and fuel. All of these factors result in a highly time-dependent emission of particulate matter (PM) 2.5 µm or less in aerodynamic diameter (PM_2.5)—even on a mass concentration basis. Control measures are frequently taken on the basis of low-reliability parameters such as emission factors and loosely established mass ratios of PM_2.5 to PM 10 µm or less in aerodynamic diameter (PM₁₀). The new environmental requirements could entail unexpected and undesired drawbacks and uncertainties in the meaning and effectiveness of process improvement measures. The development of process-integrated and flue-gas cleaning measures for reduction of particle emissions requires a better knowledge of generation mechanisms during melting. Available aerosol analyzers expand the range of control issues to be tackled and contribute to greatly reduce the uncertainty of engineering decisions on trace pollutant control. This approach combines real-time size distribution monitoring and cascade impactors as preseparators for chemical or morphological analysis. The results allow for establishing a design rationale and performance requirement for control devices. A number size distribution below 10 µm in aerodynamic equivalent diameter was chosen as the main indicator of charge influence and filter performance. Size distribution is trimodal, with a coarse mode more than 12 µm that contributes up to 30% of the total mass. A temporal series for these data leads to identification of the most relevant size ranges for a specific furnace (e.g., the most penetrating size range). In this cupola, this size range is between 0.32 and 0.77 µm of aerodynamic equivalent diameter and defines the pollution control strategy for metals concentrating within this size range. Scrap quality effect is best monitored at less than 0.2 µm in aerodynamic equivalent diameter and has been confirmed as strongly dependent on the physical state of the charge.     

Chemical characteristics of fine particulate matters measured during severe winter haze events in Ulaanbaatar,Mongolia

In order to investigate the chemical characteristics of atmospheric aerosol measured during a severe winter haze event, 12-hr PM_2.5 (particulate matter with an aerodynamic diameter ≤2.5 μm) samples were collected at an urban site in Ulaanbaatar, Mongolia, from January 9 to February 17, 2008. On average, 12-hr PM_2.5 mass concentration was 105.1 ± 34.9 μg/m³. Low PM_2.5 mass concentrations were measured when low pressure developed over central Mongolia. The 12-hr average organic mass by carbon (OMC) varied from 6.4 to 132.3 μg/m³, with a mean of 54.9 ± 25.4 μg/m³, whereas elemental carbon (EC) concentration ranged from 0.1 to 3.6 μgC/m³, with a mean of 1.5 ± 0.8 μgC/m³. Ammonium sulfate was found to be the most abundant water-soluble ionic component in Ulaanbaatar during the sampling period, with an average concentration of 11.3 ± 5.0 μg/m³. In order to characterize the effect of air mass pathway on fine particulate matter characteristics, 5-day back-trajectory analysis was conducted, using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. The haze level was classified into three categories, based on the 5-day air mass back trajectories, as Stagnant (ST), Continental (CT), and Low Pressure (LP) cases. PM_2.5 mass concentration during the Stagnant condition was approximately 2.5 times higher than that during the Low Pressure condition, mainly due to increased pollutant concentration of OMC and secondary ammonium sulfate.

Implications: Mongolia is experiencing rapid rates of urbanization similar to other Asian countries, resulting in air pollution problems by the growing number of automobiles and industrialization. Ulaanbaatar, capital of Mongolia, is inherently vulnerable to air pollution because of its emission sources, topography, and meteorological characteristics. Very limited measurements on chemical characteristics of particulate matter have been carried out in Ulaanbaatar, Mongolia.     

Analysis of a Summertime PM2.5 and Haze Episode in the Mid-Atlantic Region

Abstract

Observations of the mass and chemical composition of particles less than 2.5 μm in aerodynamic diameter (PM_2.5), light extinction, and meteorology in the urban Baltimore-Washington corridor during July 1999 and July 2000 are presented and analyzed to study summertime haze formation in the mid-Atlantic region. The mass fraction of ammoniated sulfate (SO₄ ^2-) and carbonaceous material in PM_2.5 were each ～50% for cleaner air (PM_2.5 < 10 μg/m³) but changed to ～60% and ～20%, respectively, for more polluted air (PM_2.5 > 30 μg/m³). This signifies the role of SO₄ ^2- in haze formation. Comparisons of data from this study with the Interagency Monitoring of Protected Visual Environments network suggest that SO₄ ^2? is more regional than carbonaceous material and originates in part from upwind source regions. The light extinction coefficient is well correlated to PM_2.5 mass plus water associated with inorganic salt, leading to a mass extinction efficiency of 7.6 ± 1.7 m²/g for hydrated aerosol. The most serious haze episode occurring between July 15 and 19, 1999, was characterized by westerly transport and recirculation slowing removal of pollutants. At the peak of this episode, 1-hr PM_2.5 concentration reached ～45 μg/m³, visual range dropped to ～5 km, and aerosol water likely contributed to ～40% of the light extinction coefficient.     

Atmospheric deposition of fluoride in the lower Tamar Valley,Tasmania

Soluble fluoride (F⁻), measured using an ion-selective electrode, was monitored during 1982–1983 in monthly bulk (wet and dry) atmospheric deposition samples collected at 17 locations in the lower Tamar Valley, Tasmania, where an aluminium (Al) smelter is located. Glass samplers (funnel-bottle type) were used, with duplications by plastic samplers at five locations later. The spatial and temporal variations in F⁻ deposition in relation to wind flow and rainfall are discussed, and its impact on the environment is highlighted. The mean deposition rates of F⁻, as measured from September 1982 to August 1983, ranged from about 90 μg m⁻² day⁻¹ at the intended ‘background’ location to 12,568 μg m⁻²day⁻¹ at a location about 1 km east-southeast from the smelter. The depositional fluxes of F⁻ and insoluble Al (another elemental tracer of the smelter) are significantly correlated (P < 0.001). They were much higher within 3 km of the smelter, where vegetation damage by fluoride contamination was most evident. However, air emissions from the smelter could travel at least 10 km up the valley. Wet deposition was the predominant removal process for F⁻ during autumn and winter, while dry deposition appeared to be more significant in summer. The plastic samplers collected about 8 and 17% more F⁻ and Al, respectively, but with higher standard deviations. Thus the variations observed could be largely due to sampling fluctuations.     

Influence of meteorological factors on air pollution concentration for a coastal region in India

A long-term study of measurement of concentration of NO_x, SO₂ and TSP pollutants have been done in a port and harbour region in India. Monthly measurements of gaseous and particulate pollutants were made at six monitoring stations from January 1997 to December 2000. Meteorological data was also simultaneously collected. In this study, the relationship between monitored ambient air quality data and meteorological factors, such as wind speed, temperature, is statistically analysed, using the SPSS package. The monthly mean concentrations of NO_x, SO₂ and TSP were in the range of 19.5–59.0 μg/m3, 8.6–51.3 μg/m3 and 88.2–199.3 μg/m3, respectively. The results show that TSP is strongly correlated with NO_x and SO₂ with a correlation coefficient of 0.83 and 0.82, respectively. The correlation coefficients for TSP, NO_x, and SO₂ with wind are –0.78, –0.78, and –0.88, respectively.     

Airborne lead levels in the Korean peninsula: characterization of temporal and spatial patterns and cancer risk analysis

Introduction

This study collected long-term airborne lead concentrations in the Korean peninsula and analyzed their temporal, spatial, and cancer risk characterization.

Methods

Approximately, 12,000 airborne samples of total suspended particulate (TSP) were collected from 30 ambient air monitoring stations in inland (Daegu, Daejeon, Gwangju, and Seoul) cities and portal cities (Incheon, Busan, and Ulsan) over a period of 7?years (2004?C2010). High volume air samplers were employed to collect daily TSP samples during the second week of the consecutive months throughout the entire study period. The concentrations of Pb extracted from the TSP samples were analyzed using either inductively coupled plasma-atomic emission or flame atomic absorption spectrometry.

Results

The long-term high mean Pb concentrations were observed in the port cities including Incheon (88?±?18?ng/m³), Ulsan (61?±?7?ng/m³), and Busan (58?±?6?ng/m³). In the temporal analysis, seasonal mean Pb levels were relatively higher in winter and spring than those in summer and fall. In the spatial analysis, the mean Pb levels in spring, winter, and fall from Incheon, which showed the highest seasonal concentrations except summer, were 110?±?19, 101?±?18, and 76?±?23?ng/m³, respectively. In summer, the highest seasonal mean Pb level was observed in the largest industrial city and the second port city, Ulsan (78?±?15?ng/m³), followed by Incheon (65?±?13?ng/m³).

Conclusion

The estimated excess cancer risk analysis showed that inhalation of Pb could result in cancer for one or two persons per million of population in the Korean peninsula.     

Feasibility of using low-cost portable particle monitors for measurement of fine and coarse particulate matter in urban ambient air

Exposure to ambient particulate matter (PM) is known as a significant risk factor for mortality and morbidity due to cardiorespiratory causes. Owing to increased interest in assessing personal and community exposures to PM, we evaluated the feasibility of employing a low-cost portable direct-reading instrument for measurement of ambient air PM exposure. A Dylos DC 1700 PM sensor was collocated with a Grimm 11-R in an urban residential area of Houston Texas. The 1-min averages of particle number concentrations for sizes between 0.5 and 2.5 µm (small size) and sizes larger than 2.5 µm (large size) from a DC 1700 were compared with the 1-min averages of PM_2.5 (aerodynamic size less than 2.5 µm) and coarse PM (aerodynamic size between 2.5 and 10 µm) concentrations from a Grimm 11-R. We used a linear regression equation to convert DC 1700 number concentrations to mass concentrations, utilizing measurements from the Grimm 11-R. The estimated average DC 1700 PM_2.5 concentration (13.2 ± 13.7 µg/m³) was similar to the average measured Grimm 11-R PM_2.5 concentration (11.3 ± 15.1 µg/m³). The overall correlation (r²) for PM_2.5 between the DC 1700 and Grimm 11-R was 0.778. The estimated average coarse PM concentration from the DC 1700 (5.6 ± 12.1 µg/m³) was also similar to that measured with the Grimm 11-R (4.8 ± 16.5 µg/m³) with an r² of 0.481. The effects of relative humidity and particle size on the association between the DC 1700 and the Grimm 11-R results were also examined. The calculated PM mass concentrations from the DC 1700 were close to those measured with the Grimm 11-R when relative humidity was less than 60% for both PM_2.5 and coarse PM. Particle size distribution was more important for the association of coarse PM between the DC 1700 and Grimm 11-R than it was for PM_2.5.

Implications: The performance of a low-cost particulate matter (PM) sensor was evaluated in an urban residential area. Both PM_2.5 and coarse PM (PM_10-2.5) mass concentrations were estimated using a DC1700 PM sensor. The calculated PM mass concentrations from the number concentrations of DC 1700 were close to those measured with the Grimm 11-R when relative humidity was less than 60% for both PM_2.5 and coarse PM. Particle size distribution was more important for the association of coarse PM between the DC 1700 and Grimm 11-R than it was for PM_2.5.     

Indoor particle size distributions in homes with open fires and improved Patsari cook stoves

Particulate pollution has been clearly linked with adverse health impacts from open fire cookstoves, and indoor air concentrations are frequently used as a proxy for exposures in health studies. Implicit are the assumptions that the size distributions for the open fire and improved stove are not significantly different, and that the relationship between indoor concentrations and personal exposures is the same between stoves. To evaluate the impact of these assumptions size distributions of particulate matter in indoor air were measured with the Sioutas cascade impactor in homes using open fires and improved Patsari stoves in a rural Purepecha community in Michoacan, Mexico. On average indoor concentrations of particles less than 0.25 μm were 72% reduced in homes with improved Patsari stoves, reflecting a reduced contribution of this size fraction to PM_2.5 mass concentrations from 68% to 48%. As a result the mass median diameter of indoor PM_2.5 particulate matter was increased by 29% with the Patsari improved stove compared to the open fire (from 0.42 μm to 0.59 μm, respectively). Personal PM_2.5 exposure concentrations for women in homes using open fires were approximately 61% of indoor concentration levels (156 μg m^?3 and 257 μg m^?3 respectively). In contrast personal exposure concentrations were 77% times indoor air concentration levels for women in homes using improved Patsari stoves (78 μg m^?3and 101 μg m^?3 respectively). Thus, if indoor air concentrations are used in health and epidemiologic studies significant bias may result if the shift in size distribution and the change in relationship between indoor air concentrations and personal exposure concentrations are not accounted for between different stove types.