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Asthmatics may suffer harmful health effects from air pollution. This year-long study, which was conducted from November 2015 till October 2016 and resulted in 12,045 data points from 33 participants, assessed the relationships (with a 95% confidence interval [CI]) between measured air pollutant (CO, NO2, O3, SO2, PM2.5 and PM10) concentrations and peak expiratory flow rates (PEFRs) among adults with asthma in the district of Mae Moh in Lampang, Thailand. A positive correlation was found between the mean daily concentration of NO2 from 4 days prior (“lag 4”) and the PEFR upon waking (“morning PEFR”), with an increase of 1 ppb in the former being associated with an increase of 1.34 L min–1 (95% CI: 0.25, 2.44) in the latter. Also, the interaction between NO2 (lag 4) and PM10 (lag 6) was multiplicatively associated with a decrease of –0.015 L min–1 in the morning PEFR, which was also negatively associated with the maximum daily concentration (“max”) of NO2 (lag 2) and that of PM10 (lag 6), with coefficients of –0.07 and –0.013, respectively. Furthermore, when including PM2.5 max in the generalized estimating equation model, only NO2 max (lag 2) and CO max (lag 6) were negatively associated with the morning PEFR, displaying coefficients of –0.08 and –1.71, respectively. O3 max (lag 3) and PM2.5 max exhibited positive relationships with the PEFR before sleeping (“evening PEFR”), with coefficients of 0.078 and 0.029, respectively. Additionally, the average daily PEFR was positively associated with the average daily concentration of NO2 (lag 4), with a coefficient of 0.15, but negatively associated with that of SO2, with a coefficient of –0.47. We also observed a negative relationship between the average daily PEFR and NO2 max (lag 2), with a coefficient of –0.05, but a positive one between the former and O3 max (lag 3), with a coefficient of 0.06. Our results indicate that the delayed—and, in some cases, negative—effects of these pollutants on PEFRs must be considered in health forecasting and that preventative measures should be implemented to control certain emissions at the source.

A rotating filtration device (RFD) that is filled with porous media is developed for sampling particulate matter with a diameter of 1 μm or less (PM1). An experiment is conducted on a test system using corn oil as a test aerosol. The RFD was evaluated using an aerodynamic particle sizer. The results yielded cutoff sizes of 1.68 μm and 1.04 μm at rotational speeds of 0 rpm and 9000 rpm, respectively, with foam with 80 pores per inch (ppi), a thickness of 80 mm, and a face velocity of 13.5 cm/s. When the foam was replaced with 94 ppi nickel mesh, the cutoff size decreased from 1.45 μm to 0.98 μm as the thickness increased from 17 to 68 mm. As the face velocity of the RFD increased from 13.5 to 108.3 cm/s, the cutoff size declined from 1.04 μm to 0.77 μm. Most of the changes in the cutoff sizes of the RFD were statistically significant (p

Size-segregated aerosol samples collected from a rural site (Rajim: 20˚59′N and 81˚55′E) in eastern central India during the winter of 2011 were analyzed for anhydrosugars, sugar alcohols and primary sugars to better understand their potential sources and formation. Anhydrosugars showed the predominance of levoglucosan, whereas sugar alcohol showed the predominance of mannitol, with glucose as a major primary sugar in the sub-micron (Da 1.1 μm). Levoglucosan gave a bimodal size distribution pattern with a major peak at 0.43–0.65 μm in the sub-micron mode during period 2 and period 3, suggesting its origin from biomass burning, whereas during period 1 the major peak was found at 4.4–5.8 μm in super-micron mode that may be due to the mixing of biomass burning derived particles with soil dust particles. Sugar alcohols (arabitol and mannitol) and primary sugars (glucose and trehalose) showed bimodal size distribution trend with a major peak at 4.4–5.8 μm in super-micron mode during all periods, perhaps due to fungal activity and soil dust re-suspension, respectively. The potential ingress of biomass burning derived particles into the lungs was calculated to be high whereas fungal spores and soil particles were more likely found in the upper respiratory tract. Principal component analysis and correlation analysis showed that biomass burning was a major source in the sub-micron mode whereas fungal spores and vegetative soil were dominant sources for quantified sugars in super-micron mode.

Light-absorbing organic carbon (or brown carbon, BrC) has been recognized as a critical driver in regional-to-global climate change on account of its significant contribution to light absorption. BrC sources vary from primary combustion processes (burning of biomass, biofuel, and fossil fuel) to secondary formation in the atmosphere. This paper investigated the light-absorbing properties of BrC such as site-specific mass absorption cross-section (MACBrC), absorption Angstrom exponent (AAEBrC), and the absorbing component of the refractive index (kBrC) by using light absorption measurements from a 7-wavelength aethalometer over an urban environment of Chiang Mai, Thailand in northern peninsular Southeast Asia (PSEA), from March to April 2016. The contribution of BrC to total aerosol absorption (mean ± SD) was 46 ± 9%, 29 ± 7%, 24 ± 6%, 20 ± 4%, and 15 ± 3% at 370, 470, 520, 590, and 660 nm, respectively, highlighting the significant influence of BrC absorption on the radiative imbalance over northern PSEA. Strong and significant associations between BrC light absorption and biomass-burning (BB) organic tracers highlighted the influence of primary BB emissions. The median MACBrC and kBrC values at 370 nm were 2.4 m2 g−1 and 0.12, respectively. The fractional contribution of solar radiation absorbed by BrC relative to BC (mean ± SD) in the 370–950 nm range was estimated to be 34 ± 7%, which can significantly influence the regional radiation budget and consequently atmospheric photochemistry. This study provides valuable information to understand BrC absorption over northern PSEA and can be used in model simulations to reassess the regional climatic impact with greater accuracy.

Water-soluble organic compounds are important constituents of atmospheric aerosols and have been recognized as unique fingerprints to identify atmospheric processes. Fine aerosol samples (PM2.5) were collected at Ambikapur (23.1°N and 83.2°E) in eastern central India from March to June 2017. The samples were analyzed for water-soluble dicarboxylic acids (C2–C12), glyoxylic acid (ωC2), glyoxal (Gly), methylglyoxal (MeGly), organic carbon (OC), elemental carbon (EC) and water-soluble OC (WSOC). Oxalic acid (C2) was detected as the most abundant species, followed by succinic (C4) and malonic (C3) acids. Temporal variation in concentrations of C2 diacid and related compounds was pronounced from early to late April when biomass burning (BB) was dominant in eastern central India. Strong positive correlations of C2 diacid and related compounds with levoglucosan (r = 0.83–0.99) further demonstrate that organic aerosols (OAs) were affected by BB in eastern central India. Strong positive correlations of C2 with saturated diacids (C3–C9: r = 0.78–0.97), ωC2 (r = 0.98), Gly (r = 0.96) and MeGly (r = 0.84) suggest that their sources and formation processes were similar and oxalic acid might be produced via the photochemical degradation of precursor compounds. The relatively high ratios of WSOC to OC (avg. 0.69) and C3 to C4 diacid (avg. 0.95) suggest that water-soluble OAs were photochemically processed during the campaign. The total water-soluble organic compounds detected in Ambikapur PM2.5 samples accounted for an average of 1.9% (1.1–3.1%) of OC. Our results demonstrate that BB and photochemical processing caused high levels of water-soluble organic compounds over eastern central India.

Despite the extensive use of the Internet, printed newspapers remain a primary information source. In this study, reading a newspaper in a relatively confined or poorly ventilated indoor space was simulated to determine the profile of particles released from the newspaper into the air. The consecutive simulated conditions were reading without agitation of the newspaper (NoAg), followed by reading with agitation of the newspaper (Ag) and post-reading absent the newspaper (PostR), repeated with four newspapers. We found that particle number concentration (ΣN) fell during Ag owing to electroadhesion of ultrafine particles (200 nm) caused by static charges created by friction between the paper surface and the air as a result of newspaper agitation. Conversely, particle surface area concentrations (ΣA) and particle volume concentrations (ΣV) increased significantly during Ag. This was because the larger, fine (1-2.5 μm) and coarse mode (2.5-10 μm), particles were detached from the newspaper during agitation due to inertial detachment - the release of even a small number of these particles contributing greatly to ΣA and ΣV. The critical particle number diameter (CPND) occurred at 207-310 nm. Particles smaller than this were subject to electroadhesion during Ag. The critical particle volume diameter (CPVD) occurred at 130-497 nm. Particles larger than this were subject to inertial detachment during Ag. These observations indicate that the electroadhesion of smaller particles and the inertial detachment of larger particles occur simultaneously. Particle mass concentrations were found to be as high as 168.7-534.3 μg m

Cooking oil fumes (CF) coming from night market stalls exhaust contain substantial amounts of air pollutants such as carbonyl compounds that may contribute to outdoor air pollution and may have adverse health effects on the Taiwanese population. Carbonyl emission characteristics depend on several factors, which include but are not limited to, the cooking style and food material being used. The current study evaluated carbonyl compound emissions from two scenarios: a standard kitchen cooking classroom with a stack gas tunnel and night market food stalls. The different cooking styles and food types cooked using a liquefied petroleum gas (LPG) stove, such as grilled chicken with (GCS) and without sauce (GC), mixed barbecue with sauce (MBS), grilled vegetables with sauce (GVS), stir-fried oyster omelet (OM), fried Taiwanese chicken nuggets (FN) in the kitchen cooking classroom, and grilled chicken with (GCS) and without sauce (GC), stir-fried oyster omelet (OM), grilled vegetables with sauce (GVS), and fried steak (FS) in the night market were evaluated for carbonyl carbon emissions. OM from the kitchen classroom and GCS from the night market showed the highest mean total carbonyl compound concentrations (1850 ± 682 ppb and 1840 ppb). Formaldehyde was found to be the most predominant carbonyl compound, with contribution percentages ranging from 70.9–99.58% of the total carbonyl emission factors in CFs. Grilled vegetables with sauce had the highest emission factor magnitude of 274 µg kg–1 wt. Factors such as the addition of sauce and grilling were also observed to increase carbonyl compound emissions. Corresponding health risks of carbonyl compounds in CFs for the night market vendors were also assessed. All values for cancer risk (R) were above the standard R value for workplace exposure, and HQ values were all greater than 1, suggesting a high risk for adverse health effects. Although our reported values were relatively high due to our sampling conditions, our study was first to be conducted in Taiwan and holds an important contribution to the global existing data of carbonyl compound emissions.

This study systemically investigated the ambient PM2.5 (n=108) with comprehensive analyses of the chemical composition, identification of the potential contributors, and estimation of the resultant respiratory physician visits in the residential regions near energy-consuming and high-polluting industries in central Taiwan. The positive matrix fraction (PMF) model with chemical profiles of trace metals, water-soluble ions, and organic/elemental carbons (OC/EC) was applied to quantify the potential sources of PM2.5. The influences of local sources were also explored using the conditional probability function (CPF). Associations between the daily PM2.5 concentration and the risk of respiratory physician visits for the elderly (≥65years of age) were estimated using time-series analysis. A seasonal variation, with higher concentrations of PM2.5, metals (As, Cd, Sb, and Pb), OC/EC and ions (i.e., NO3-, SO42- and NH4+) in the winter than in the spring and summer, was observed. Overall, an increase of 10μgm-3 in the same-day PM2.5 was associated with an ~2% (95% CI: 1.5%-2.5%) increase in respiratory physician visits. Considering the health benefits of an effective reduction, we suggest that the emission from coal combustion (23.5%), iron ore and steel industry (17.1%), and non-ferrous metallurgy (14.4%), accounting for ~70% of the primary PM2.5 in the winter are prioritized to control.

This study investigated allergenic terpenol compounds in incense powder and smoke. The powder of two Thai brands contained higher concentrations of terpenols up to 6.15 times higher than those of two Taiwanese brands. Consequently, Thai incense makers face a higher potential risk of contact dermatitis than Taiwanese incense makers do. d -Limonene was the primary terpenol compound in the powder of Thai B (64.0%) and Thai Y (31.5%), sold in Thailand. By contrast, anisyl alcohol was the primary terpenol compound in the powder of LST (40.3%) and SC (37.7%), sold in Taiwan. After the four brands of incense were ignited, their mean PM 2.5 emission factor was 18.02 ± 6.20 mg g − 1 incense. The PM 2.5 mass emission factors of the Taiwanese brands were far higher than those of the Thai brands, and so were the PM 2.5 terpenol emission factors, showing that the smokes of the Taiwanese incense were potentially more allergenic than those of the Thai incense. Geraniol, the most allergenic terpenol compound, was 2.8%–10.7% of total terpenol compounds in the powder of the four brands, yet was the main contributor to PM 2.5 , constituting 66.3%–83.5% of terpenol compounds in the smokes of the four brands. Furthermore, geraniol exhibited an IP ratio, defined as the incense/powder (IP) ratio of terpenol-related species, > 1 in all four brands, and > 5 in the Taiwanese brands, suggesting a greater health risk with the smoke from the Taiwanese incense. The IP ratios of other terpenol species were all 1, meaning that the generation of PM 2.5 terpenol compounds was potentially enhanced by indoor lighting.

Taiwan's rivers dry during the winter, exposing large areas of river bed and leading to airborne aeolian river dust. This study used PM10 and windspeed data taken from monitoring stations local to the Zhuoshui River (the river with the largest exposed area in Taiwan) to investigate the relationship between airborne river dust and air quality, and subsequently to estimate river dust emissions. During river dust events, PM10 concentrations were significantly and positively correlated with wind speeds exceeding 5 m/s (the critical wind speed). FPG Lunbei station, located downwind (south of the river) and the closest station to the river, recorded an average hourly PM10 concentration of 189 ± 193 μg/m3 an average correlation coefficient (r) of 0.94 between hourly PM10 concentration and average hourly wind speed, an average annual dust occurrence rate of 15%, and a maximum PM10 concentration exceeding 1000 μg/m3. PM2.5 increased with PM10, albeit at a disproportional rate. When hourly PM10 concentration exceeded 200 μg/m3, most of the particulates in the dust were coarse particulates (PM2.5–10). An hourly PM2.5/PM10 ratio of

Carcinogenic polycyclic aromatic hydrocarbons (cPAHs) in ambient PM2.5 and a specific molecular marker of biomass burning, levoglucosan, are used to investigate the influence on public health of biomass burning. In this work, we present an effective method for one-time analysis of cPAHs and levoglucosan by GC-MS without derivatization. The method was applied for the analysis of PM2.5 samples (64.3 ± 17.6 μg m−3, n = 57) collected during a smoke haze period in Chiang Mai, Thailand. Levoglucosan was analyzed by using both the developed method (GC-MS) and a reference method (HPAEC-PAD) for comparison. Its average concentration obtained from GC-MS (0.31 ± 0.21 μg m−3) was about 4 times less than the concentration obtained from the reference method (1.22 ± 0.76 μg m−3). Therefore, a correcting factor (CF = 4) was used as a multiplying factor, to obtain a comparative value (1.23 ± 0.86 μg m−3). The average concentration of cPAHs found in PM2.5 samples was 5.88 ± 1.97 ng m−3 with the highest value of 10.86 ng m−3 indicating medium to high cancer risk due to PAHs exposure when referring to values of toxicity equivalence and inhalation cancer risk. Diagnostic ratios of BaA/(BaA + CHR) (0.48 ± 0.04) and IND/(IND + BPER) (0.58 ± 0.04) and strong correlations between PM2.5, levoglucosan and cPAHs concentrations implied that the major source of air pollution in the study period was biomass burning. PM2.5 concentration as a pollution indicator was labelled as BB-low, BB-medium, BB-high or BB-extreme; 100 μg m−3, respectively. The levoglucosan and cPAHs concentration during BB-extreme pollution was 4.3 times and 2.34 times, respectively, that during BB-low pollution, and the correlation coefficient (r) between the concentrations of levoglucosan and cPAHs was as high as 0.987, indicating that the more intense the burning of biomass, the higher the carcinogenic risk in the urban air.

An open-system combustion chamber was designed and constructed for simulation of burning of various biomass types to estimate emission factors of pollutant gases, fine particulate matters and their composition to find out significant tracers. Rice straw (RS), maize residues (MR) and forest leaf litters (FLL) from mixed deciduous forest (MDF) and dry dipterocarp forest (DDF) were collected from various places in Northern Thailand based on land-use types. Approximately 1 kg of air-dried biomass sample was burned in the chamber, PM2.5 were collected. CO2 dominated during the flaming state while CO is predominant in the smoldering state. The highest EFPM2.5 was obtained from MDF burning (4.38 ± 2.99 g kg−1), while the lowest value was from MR burning (2.15 ± 0.95 g kg−1). Among water soluble ions, K+ (biomass burning (BB) tracer) was the most abundant species in PM2.5 followed by Cl− and SO42−. The average EFK+ from the burning of agricultural biomass was significantly higher than the burning of FLL. Scatter plot of K+/SO42− versus K+/Cl− can be used to distinguish between agricultural crop residues and FLL burning. Levoglucosan (BB tracer) was a dominant species among anhydrosugars and also a major component found in FLL burning. The ratios of levoglucosan/K+ and levoglucosan/mannosan obtained from forest and agricultural waste burnings were significantly different, therefore they can be used for BB source identification.

Two portable, battery powered particle size distribution analyzers, TSI NanoScan scanning mobility particle sizer (TSI NanoScan SMPS 3910, USA) and Kanomax Portable Aerosol Mobility Spectrometer (Kanomax PAMS 3300, Japan), have been recently introduced to the market. Both are compact and allow researchers to rapidly measure and monitor ambient or indoor ultrafine and nanoparticles in real time. In addition, both instruments apply the SMPS measuring scheme, utilizing a corona charger in place of a radioactive neutralizer, and are integrated with a hand-held condensation particle counter (CPC). In this study, the different designs, flow schemes, and operational settings of both instruments have been summarized based on the information released by the manufacturers and the available published literature. The performance characteristics and monitoring capability of these two portable ultrafine to nanoparticle sizers were investigated and compared to a reference TSI 3936 lab-based SMPS under identical conditions. Reasonable agreement was found between the three instruments in terms of their efficiency in sizing and counting polydispersed particles. Of the two portable analyzers, PAMS was able to provide a higher sizing resolution for monodispersed particle measurements than NanoScan, when operated under the High Mode (higher sheath to aerosol flow ratio).

Three biodiesels and two aftertreatments were tested on a heavy-duty diesel engine under the US FTP transient cycle and additional four steady engine loads. The objective was to examine their effects on the gaseous and particulate emissions, with emphasis given to the organic and elemental carbon (OC and EC) in the total particulate matter. Negligible differences were observed between the low-sulfur (B1S50) and ultralow-sulfur (B1S10) biodiesels, whereas small reductions of OC were identified with the 10% biodiesel blend (B10). The use of diesel oxidation catalyst (DOC1) showed moderate reductions of EC and particularly OC, resulting in the OC/EC ratio well below unity. The use of DOC plus diesel particulate filter (DOC2+DPF) yielded substantial reductions of OC and particularly EC, resulting in the OC/EC ratio well above unity. The OC/EC ratios were substantially above unity at idle and low load, whereas below unity at medium and high load. The above changes in particulate OC and EC are discussed with respect to the fuel content, pollutant removal mechanisms and engine combustion conditions. Overall, the present study shows that the carbonaceous composition of PM could change drastically with engine load and aftertreatments, and to a lesser extent with the biodiesels under study.

The Mid-Autumn Festival (MAF), or Moon Festival, is a harvest festival in Taiwan, celebrated by families across the island with evening barbecues outside. This study investigated the potential impact of these activities on the air quality in Tainan, a city in southern Taiwan. Fine particulate matter (PM2.5) was examined in the period leading up to the MAF (pre-MAF), during the Festival (MAF), after the Festival (post-MAF), and in the period after this (a period of moderate air quality: MAQ). Gaseous pollutants in PM2.5 were, from highest to lowest mean concentration, NH3, SO2, HCl, HNO3, HNO2, and oxalic acid, while inorganic salts were mainly in the form of the photochemical products SO4(2-), NH4(+), and NO3(-). These inorganic salts accounted for 37.6%-44.5% of the PM2.5 mass concentration, while a further 26.3%-42.8% of the PM2.5 mass was total carbon (TC). TC was mostly composed of organic carbon (OC) produced by photochemical reactions. Of this, 9.8%-14.9% was carboxylates, of which oxalate was the most abundant compound, accounting for 22.8%-31.9% of carboxylates. The presence of phthalates in the PM2.5 indicated emissions from the plastics industry. Although a noticeable amount of aerosol was produced by festival activities and burning of softwood and hardwood, onshore air currents during the festival prevented potential high aerosol loading. During the moderate air quality period following post-MAF, the concentration of total carbohydrates was 1.44-2.64 times the amount during the festival. Levoglucosan and myo-inositol accounted for 81.7%-89.6% of the total carbohydrate concentration. The average Levo/Manno ratio was 18.64 ± 5.24. The concentration of levoglucosan was closely related to that of PO4(3-), erythritol, and galactose. Backward trajectories indicated that biomass burning in China affected the air quality of Tainan City.

In spring 2013 air samples were collected from a coastal site in the sparsely populated far south-west of Taiwan and analysed for ambient gases, inorganic salts, carboxylates, and saccharides. Concentration of ambient gases was in the order SO_2 ＞ HCl ＞ HNO_3 ＞ NH_3 ＞ HNO_2. Day-night variation in concentrations indicated that photochemical conversion of HNO_2 to HNO_3 occurs during the day. PM_(2.5) (16.16 ± 5.30 μg m^(-3)) accounted for 61.1% of PM10 mass concentrations. The main inorganic salts were SO_4 ^(2-), NH_4 ^+, Na^+, NO_3 ^-, and Cl^-, collectively accounting for 48.8 ± 27.4% of the PM_(2.5). Cldepletion during the day was higher than during the night due to the presence of reactive photochemical products. The average Cl-depletion of PM_(2.5) (53.1%) was markedly higher than that of PM_(2.5-10) (26.0%), indicating that in PM_(2.5), a high amount of Cl^- reacts with acidic gases to form HCl, which then escapes into the atmosphere. The carboxylate concentration in PM_(2.5) was 0.50 ± 0.24 μg m^(-3). It was found that low-molecular-weight carboxylates formed more readily in the open coastal region than in urban regions of southern Taiwan. Additionally, the daily mean ratio of Oxalate/non-seasalt SO_4 ^(2-) (6.15 ± 2.28%) in the coastal region was higher than that in the urban regions in southern Taiwan. The most prevalent saccharide in PM_(2.5) was myo-inosital (333 ± 300 μg m^(-3)), a type of soil fungus metabolite. Emissions of arabitol and mannitol, emitted through lichen and fungal activity, were markedly higher during the day. Only a trace amount (8.92 ± 16.92 μg m^(-3)) of Levoglucosan (Levo), an indicator of biomass burning, was detected. The mean Levo/organic carbon ratio was 5.04 ± 8.72‰, suggesting that biomass burning contributed slightly to aerosols in the study area. An analysis of air mass backward trajectories showed that the products of biomass burning in Southeast Asia and southern China may be transported to the study area through long-range transport. This effect is more noticeable during the day when onshore breezes support the transport of particles sourced from the west of Taiwan.

By modulating the Earth-atmosphere energy, hydrological and biogeochemical cycles, and affecting regional-to-global weather and climate, biomass burning is recognized as one of the major factors affecting the global carbon cycle. However, few comprehensive and wide-ranging experiments have been conducted to characterize biomass-burning pollutants in Southeast Asia (SEA) or assess their regional impact on meteorology, the hydrological cycle, the radiative budget, or climate change. Recently, BASE-ASIA (Biomass-burning Aerosols in South-East Asia: Smoke Impact Assessment) and the 7-SEAS (7-South-East Asian Studies)/Dongsha Experiment were conducted during the spring seasons of 2006 and 2010 in northern SEA, respectively, to characterize the chemical, physical, and radiative properties of biomass-burning emissions near the source regions, and assess their effects. This paper provides an overview of results from these two campaigns and related studies collected in this special issue, entitled “Observation, modeling and impact studies of biomass burning and pollution in the SE Asian Environment”. This volume includes 28 papers, which provide a synopsis of the experiments, regional weather/climate, chemical characterization of biomass-burning aerosols and related pollutants in source and sink regions, the spatial distribution of air toxics (atmospheric mercury and dioxins) in source and remote areas, a characterization of aerosol physical, optical, and radiative properties, as well as modeling and impact studies. These studies, taken together, provide the first relatively complete dataset of aerosol chemistry and physical observations conducted in the source/sink region in the northern SEA, with particular emphasis on the marine boundary layer and lower free troposphere (LFT). The data, analysis and modeling included in these papers advance our present knowledge of source characterization of biomass-burning pollutants near the source regions as well as the physical and chemical processes along transport pathways. In addition, we raise key questions to be addressed by a coming deployment during springtime 2013 in northern SEA, named 7-SEAS/BASELInE (Biomass-burning Aerosols & Stratocumulus Environment: Lifecycles and Interactions Experiment). This campaign will include a synergistic approach for further exploring many key atmospheric processes (e.g., complex aerosol–cloud interactions) and impacts of biomass burning on the surface–atmosphere energy budgets during the lifecycles of biomass-burning emissions.

PM10 aerosol was collected between February and April 2010 at an urban site (CMU) and an industrial site (TOT) in Chiang Mai, Thailand, and characteristics and provenance of water-soluble inorganic species, carboxylates, anhydrosugars and sugar alcohols were investigated with particular reference to air quality, framed as episodic or non-episodic pollution. Sulfate, a product of secondary photochemical reactions, was the major inorganic salt in PM10, comprising 25.9% and 22.3% of inorganic species at CMU and TOT, respectively. Acetate was the most abundant monocarboxylate, followed by formate. Oxalate was the dominant dicarboxylate. A high acetate/formate mass ratio indicated that primary traffic-related and biomass-burning emissions contributed to Chiang Mai aerosols during episodic and non-episodic pollution. During episodic pollution carboxylate peaks indicated sourcing from photochemical reactions and/or directly from traffic-related and biomass burning processes and concentrations of specific biomarkers of biomass burning including water-soluble potassium, glutarate, oxalate and levoglucosan dramatically increased. Levoglucosan, the dominant anhydrosugar, was highly associated with water-soluble potassium (r = 0.75–0.79) and accounted for 93.4% and 93.7% of anhydrosugars at CMU and TOT, respectively, during episodic pollution. Moreover, levoglucosan during episodic pollution was 14.2–21.8 times non-episodic lows, showing clearly that emissions from biomass burning are the major cause of PM10 episodic pollution in Chiang Mai. Additionally, the average levoglucosan/mannosan mass ratio during episodic pollution was 14.1–14.9, higher than the 5.73–7.69 during non-episodic pollution, indicating that there was more hardwood burning during episodic pollution. Higher concentrations of glycerol and erythritol during episodic pollution further indicate that biomass burning activities released soil biota from forest and farmland soils.

Spherical TiO2 nano- to microparticles are rapidly synthesized by spraying clear stock solution as a nano aerosol into an atmospheric-pressure microwave plasma torch at 550–600°C. The stock solution was prepared by an initial H2O/TiCl4 (titanium tetrachloride) volume ratio of 8. At about 0.15 s, anatase TiO2 powders were produced and collected by 14-stage impactors. The size distribution shows that 98.47% of the particles in number were in the < 10-nm impactor, with the normalized particle number percentage (dn'/dlogDp) of 327.1, although the mass distribution of the powders was mainly in the size range of 2.5–6.2 μm. Scanning electron microscopy and transmission electron microscopy images show that most of the spherical TiO2 particles had a primary particle size of about 10 nm. Moreover, larger secondary particles (several μm), likely aggregated small particles were also presented. The chemical composition and elemental analyses show that the structure of the powders is mainly composed of TiO2 with traces of TiO2-xNx. Hence, the total reaction pathway is proposed as Ti(OH)xCl4-x + H2O + N2 + O2 → TiO2 nuclei + HCl + other byproducts. Moreover, the ultraviolet-visible absorption spectrum and photocatalytic performance of the synthesized powders during exposure to ultraviolet or visible light are comparable to those of commercial TiO2 powders.

Size-segregated aerosol samples were collected continuously from July 2009 to June 2010 at urban area of Raipur, the eastern central India. The collected samples were analyzed for PM10 mass and its water-soluble dicarboxylate species and major inorganic ions. Results showed that the annual mean PM10 concentration was 270.5 µg/m3, which varied from 109.8 to 455.6 µg/m3. The higher concentration of PM10 mass was found during winter season followed by spring and summer, and lower during monsoon season. High PM10 mass concentration in Raipur could be attributed to the anthropogenic activities which may include high rate of construction activities, biomass combustion and mechanical erosion from road dusts. The concentrations of total dicarboxylates (TDCs) ranged from 325.3 to 1537.7 ng/m3 with an average of 904.0 ng/m3 constituting only 0.3% of PM10 mass. The oxalate (C2) and malonate (C3) were the dominant DCs followed by succinate (C4) and phthalate (Ph). The water-soluble major inorganic ions constituted 10.0% of PM10 mass with SO42– and NO3– being the dominant species followed by Cl– and Ca2+. The concentrations of dicarboxylates and major inorganic ions also showed maxima in winter and spring than summer and monsoon seasons. The ratio of malonate to succinate was used to distinguish primary sources from secondary sources of these dicarboxylates. The average C3/C4 ratio in spring and summer was 1.6 and 2.1, respectively, which suggested a large contribution of secondary sources to particulate dicarboxylates formation. Correlation analysis of DCs with SO42– and K+ was investigated to interpret their possible secondary formation pathways. Source identification study by principal component analysis (PCA) revealed that photochemical, secondary sources and vehicular emissions were the main sources contributing to overall PM10 mass with minor contribution from paved road dust and explained almost 95.5% variance of total aerosol data set.

PM(subscript 10) samples were collected between July 2009 and June 2010 in the urban area of Durg City, India, and analyzed for water-soluble dicarboxylate species. Observed PM(subscript 10) concentrations varied from 94.0 to 432.1 μg/m^3 with an annual average of 253.5 μg/m^3. The annual average concentration of PM(subscript 10) was four times higher than the Indian Central Pollution Control Board (CPCB) National Ambient Air Quality Standard (Indian NAAQS) prescribed limit of 100 μg/m^3. The high PM(subscript 10) mass concentration in Durg City are attributed to anthropogenic activities, including a high rate of construction activities, biomass combustion and mechanical disturbance of road dusts. The highest PM(subscript 10) value was recorded during the winter, a period characterized by extensive biomass burning, especially at night, while the lowest PM(subscript 10) concentration was recorded during the monsoon, when there was significant precipitation. The highest concentrations of dicarboxylates were found during winter and spring. On average, total water-soluble dicarboxylates (966 ng/m^3) accounted for 0.39% of the PM(subscript 10) mass. Oxalate (C2), followed by malonate (C3) and succinate (C4), dominated the total mass of dicarboxylates, the sum of these three species accounting for 77.5% of the total analyzed. The malonate to succinate concentration ratio calculated in this study was higher than those reported for vehicular emissions, suggesting that in addition to vehicular exhausts, secondary formation of particulate dicarboxylates via photo-oxidation also occurred. Principal component analysis (Varimax Rotated Component Matrix) revealed that secondary aerosol formation, coal and biomass combustion, and vehicular emissions were the major sources contributing to overall PM10 mass in Durg City, India.

Diesel engine exhaust contains large numbers of submicrometer particles that degrade air quality and human health. This study examines the number emission characteristics of 10–1000 nm nonvolatile particles from a heavy-duty diesel engine, operating with various waste cooking oil biodiesel blends (B2, B10 and B20), engine loads (0%, 25%, 50% and 75%) and a diesel oxidation catalyst plus diesel particulate filter (DOC + DPF) under steady modes. For a given load, the total particle number concentrations (NTOT) decrease slightly, while the mode diameters show negligible changes with increasing biodiesel blends. For a given biodiesel blend, both the NTOT and mode diameters increase modestly with increasing load of above 25%. The NTOT at idle are highest and their size distributions are strongly affected by condensation and possible nucleation of semivolatile materials. Nonvolatile cores of diameters less than 16 nm are only observed at idle mode. The DOC + DPF shows remarkable filtration efficiency for both the core and soot particles, irrespective of the biodiesel blend and engine load under study. The NTOT post the DOC + DPF are comparable to typical ambient levels of ∼104 cm−3. This implies that, without concurrent reductions of semivolatile materials, the formation of semivolatile nucleation mode particles post the aftertreatment is highly favored.

This paper reports the atmospheric concentrations of PM2.5 and PM1 mass, water soluble inorganic components and their seasonal variations measured between the period of July 2009 and June 2010 in Durg city (20°23' to 22°02'N and 80°46' to 81°58'E), India. A cascade impactor sampler with Whatman 41 glass filters was used to collect aerosol samples in PM2.5 and PM1 size fractions. The results showed that the annual mean concentration of PM2.5 and PM1 were 135.0 µg/m3 and 64.7 µg/m3, respectively. Annual cycle shows highest concentration of PM2.5 and PM1 mass and water soluble ions in winter season and the lowest during rainy season. This is attributed to the enhanced production of aerosols and prevailing meteorological conditions. The higher PM1/PM2.5 ratio (0.48) during the whole campaign clearly indicates larger PM1 particle fractions were in PM2.5 at this location. Out of the total aerosol mass, water soluble constituents contributed an average of 11.57% (7.48% anions, 4.09% cations) in PM2.5 and 16.98% (11.14% anions, 5.85% cations) in PM1. The concentrations of SO42- and NO3- were highest in all size fractions and accounted for 32.76% and 13.38% of the total mass of the water soluble ions in PM2.5 and 32.78% and 12.21% in PM1 size fractions. Na+, Mg2+ and Ca2+, derived from the soil dust particles, were higher in spring and summer, as the dry weather in this season was favorable for the resuspension of soil particles. The seasonal variation of Cl-, K+ and secondary components (NH4+, NO3- and SO42-) were similar with high concentrations in winter and low concentrations in fall. Two principal components explaining 76.6% and 65.9% of the variance for PM2.5 and PM1 data set respectively were identified. Factor 1 has significant loading of species of anthropogenic origins and factor 2 showed partial associations with species of natural origins.

Three kinds of diesel particulate filters (DPFs) were installed on used diesel-powered vehicles to investigate their influences on air pollutant emissions. The air pollutant emissions were measured before, after and running for specific distances to assess the deterioration effect. The emission measurement was performed on a chassis dynamometer. The results show that emissions of smoke, CO and HC are all reduced after DPF installation. After 20000 km driving, the emission concentrations of the above 3 criteria air pollutants do not increase in comparison with that right after installation. When DPFs are installed, the emissions of PAHs (polycyclic aromatic hydrocarbons) are reduced by 85.6-89.4% and 69.0-89.2% for heavy-duty diesel vehicles (HDVs) and light-duty diesel vehicles (LDVs), respectively. After driving 20000 km for HDVs and 2500 km for LDVs, PAH emissions do not increase in comparison with that right after installation, indicating that the DPFs do not deteriorate after driving for the test mileages. The lower molecular weight PAHs predominates in the exhaust both before and after DPF installation. The results also show the reduction rate is higher for higher molecular weight PAHs due to their tendency to adsorb on particulate.

Fugitive metal in PM2.5 at the blast furnace (S1), reverberatory furnace (S2), and surrounding environment (S0) of a secondary aluminum smelter (a secondary ALS) was studied. PM2.5 mass concentration at the blast furnace exceeded that at the reverberatory furnace and this was especially apparent during operation, giving an early indication that the blast furnace is more important as a pollutant source. Further, PM2.5 mass concentration levels and patterns at S0 indicated that emissions from the blast furnace and reverberatory furnace were the major source of the observed fine particle pollution in the surrounding environment. Si and K were the main components and hence pollutants by mass in the PM2.5 at S1, S2 and S0 during both operation and non-operation. Hg was not detected in the PM2.5 aerosol during smelter operation but was present at all three sampling locations during non-operation. This is due to the falling blast furnace and reverberatory furnace temperatures during non-operation which cause Hg vapor formed during operation to condense to form detectable Hg particles, and hence Hg contributes to the pollutant load during non-operation. Average S1/S0 and S2/S0 mass concentration ratios of 40.32 and 18.53, respectively, for all measured metals during operation and 7.83 and 5.73 for all measured metals during non-operation indicate that metal particulate pollution at the workplaces of secondary ALSs, particularly at the blast furnace during operation, is a serious issue. S1/S0 mass concentration ratios were higher still for Pb (62.22), Ti (113.40) and Ba (248.64), while the S2/S0 mass concentration ratio for Mo was 138.20. Principal component analyses produced a PC1 that explained 32.36–48.16% of the total variance during operation of the smelter and 47.86–69.Ten percent during non-operation. Their strong component loadings were mainly related to the fugitive PM2.5 mass. Compared to atmospheric metal concentrations reported for other regions of the world, the toxic metals that have relatively higher concentrations in the secondary ALS emissions are Cr, Cd, Cu, As, Pb, Se, Al and Zn, especially during smelter operation. Concentrations of these toxic heavy metals are approximately 2–4 orders of magnitude higher than those reported for various industrial regions and metropolises with heavy traffic across the world.

1 Department of Bioenvironmental Engineering, Chung Yuan Christian University, 200, Chung-Pei Road, Chung-Li 320, Taiwan 2 Department of Environmental Engineering and Science, Chia-Nan University of Pharmacy and Science, Tainan 717, Taiwan 3 Department of Environmental Engineering and Management, Chaoyang University of Technology, Wufong, Taichung 413, Taiwan 4 Department of Tourism Management, Chia-Nan University of Pharmacy and Science, Tainan 717, Taiwan

Principal component analysis (PCA) was used to analyze variationsin visibility compared with (1) variations in meteorological variables in the period 1961 to 1998, and (2) criteria air pollutant (SO2, CO, O3, NOx and PM10) concentrations monitored between 1994 and 1998, in the Kaohsiungmetropolitan area. Whilst average visibility during the 1960'sexceeded 20km, it had deteriorated to 5–10 km in theperiod 1994 to 1998. PCA identified seven components witheigenvalues greater than one. The principal componentsidentified accounted for variability related to PM10concentration, ozone-related pollutants, oil combustion,and traffic emissions. Furthermore, spatial and temporalvariations in PM10 were consistent throughout thecity. Variation in SO2 levels followed a similarpattern at Tsoying, Shanming, Chiankin and Chiancheng.Industrial pollution and traffic emissions, SO2, COand NOx, from the Hsiaokang area remained within thearea. However, similar patterns of SO2 andNOxat Fengshan and Jenwu indicate that industrial emissionsfrom the latter were probably transported to the former.Much of the first principal component is based onPM10 variability, suggesting that, of the fivecriteria pollutants studied, PM10 is the majorcontributor to visibility deterioration. It is known thatPM2.5 concentration is more closely associated withvisibility changes than is PM10. However, becausePM10 and PM2.5 are strongly associated inKaohsiung, a targeting reduction in PM10 may imply areduction in visibility.

Visibility data from over the past four decades accumulated from urban areas of central Taiwan indicated that air pollutants have significantly degraded visibility in recent years. Currently, the annual average visibility in urban areas of the same region is approximately 8–10 km, while the visibility in remote areas is approximately 25–30 km. To understand how aerosols affect the visibility in this region, here we selected three sites in central Taiwan to measure the soluble ionic and carbonaceous species of PM 2.5 and PM 2.5–10 during 1997–1998. A MOUDI cascade impactor was used to measure the size distributions of atmospheric sulfate, nitrate, and carbonaceous particles. The aerosol data were then analyzed together with meteorological and air quality data. Comparing the results obtained from urban, coastal suburban and remote sites revealed that sulfate, carbonaceous species and local wind speed significantly affected the visibility in the urban area. However, sulfate concentration and humidity influenced visibility in the coastal area of central Taiwan. The particulate concentration at the remote station was roughly one-fifth of that in the city. Regression analysis results indicated that humidity is a dominant factor affecting remote visibility.

This investigation conducted seven intensive field measurements of PM 2.5 and PM 2.5–10 at three sites within the Taichung coastal area in Taiwan, between December 1996 and November 1997. Samples were collected for chemical analysis of soluble ionic species, elemental and organic carbon. Comparing these aerosol data with air quality and meteorological data reveals that the fractions of sulfate, nitrate, and ammonia of PM 10 on hazy days, are significantly higher than on clear days. Visibility shows a strong negative correlation with sulfate, ammonia, and nitrate and a moderately negative correlation with humidity. The average sulfur oxidation ratio and nitrogen oxidation ratio of PM 10 increases from 0.18 and 0.06, respectively, on clear days, to 0.46 and 0.12, respectively, on hazy days. These ratios indicate an enhanced formation of acidic particulates on hazy days. A regression model based on sulfate and humidity has been developed, and the comparison indicates that visibility in the coastal area can be properly simulated by the equation derived herein.

Organic molecular markers are important atmospheric constituents. Their formation and sources are important aspects of the study of urban and rural air quality. We collected PM10 aerosol samples from the Mahanadi Riverside Basin (MRB), a rural part of eastern central India, during the winter of 2011. PM10 aerosols were characterized for molecular markers using ion chromatography. The concentration of PM10 ranged from 208.8 to 588.3 μg m(-3) with a mean concentration of 388.9 μg m(-3). Total concentration of anhydrosugars, sugar alcohols, primary sugars, and oxalate were found to be 3.25, 5.60, 10.52, and 0.37 μg m(-3), respectively, during the study period. Glucose was the most abundant species followed by levoglucosan and mannitol. Significant positive correlation between the molecular markers, anhydrosugars, sugar alcohols, primary sugars, and oxalic acid confirmed that biomass burning, biogenic activity, and re-suspension of soil particles were the main sources of aerosol in the eastern central India study area.

PM10 aerosol samples were collected in Durg City, India from July 2009 to June 2010 using an Andersen aerosol sampler and analyzed for eight water-soluble ionic species, namely, Na+, NH4 +, K+, Mg2+, Ca2+, Cl−, NO3 − and SO4 2− by ion chromatography. The annual average concentration of PM10 (253.5 ± 99.4 μg/m3) was four times higher than the Indian National Ambient Air Quality Standard of 60 μg/m3 prescribed by the Central Pollution Control Board, India. The three most abundant ions were SO4 2−, NO3 −, and NH4 +, with average concentrations of 8.88 ± 4.81, 5.63 ± 2.22, and 5.18 ± 1.76 μg/m3, respectively, and in turn accounting for 27.1 %, 16.5 %, and 15.5 % of the total water-soluble ions analyzed. Seasonal variation was similar for all secondary ions i.e., SO4 2−, NO3 −, and NH4 +, with high concentrations during winter and low concentrations during monsoon. Varimax Rotated Component Matrix principal component analysis identified secondary aerosols, crustal resuspension, and coal and biomass burning as common sources of PM10 in Durg City, India.

Visibility trends on the island of Taiwan were investigated employing visibility and meteorological (1961-2003), and air pollutant (1994-2003) data from one highly urbanized center (Taipei), one highly industrialized center (Kaohsiung), and two rural centers (Hualien and Taitung). Average annual visibility (1961-2003) was significantly higher at the rural centers. Unlike at the other centers, visibility in Taipei improved between 1992 (6.6 km) and 2003 (9.9 km), and this can be linked to the construction and expansion of a mass transit rail system in Taipei, the use of which has helped reduce emissions of traffic related air pollutants, particles, and NO2. This has left Kaohsiung with the lowest annual visibility since 1994, despite its 1961-2003 average being superior to that of Taipei. Precipitation lowers visibility, as demonstrated by the all-centers correlation coefficient for visibility and precipitation of -0.92. Hence, frequency of precipitation is one of the factors contributing to the average annual visibility number. The poorest air quality category ('episode'), most commonly experienced in Taipei and Kaohsiung, was characterized by relatively high concentrations of PM10 and NOx at those centers, with comparatively high atmospheric pressure and comparatively low visibility and wind speed. Excepting O3, pollutant concentrations were slightly higher during weekdays, although there was no consistent, significant difference in weekday-weekend visibility. Principal component analysis demonstrated that visibility was markedly reduced in Taipei, Kaohsiung, and Hualien by increased vehicular emissions, road traffic dust, and industrial activity, but not in Taitung, where visibility was as a result superior to that at the other centers and degradation in visibility was likely a response to long-range transport of pollutants rather than local sources. Optimal empirical regression models indicated a negative impact on visibility for each of PM10, SO2 and NO2, particularly so for PM10, and validity of these models for Taipei, Kaohsiung, and Hualien was confirmed by correlation coefficients of simulated and observed average visibility of 0.63-0.72 for daily visibility and 0.85-0.88 for monthly visibility. For Taitung these figures were only 0.46 and 0.50, respectively, indicating that simulations for Taitung should include long-range transport as a pollutant source.

Ambient PM10 aerosol samples were collected from Taiwan's Taichung metropolitan basin between October 1997 and January 1998, and their chemical characteristics studied. The average mass concentration of PM10 was 109.0 +/- 54.1 microg/m3. Carbonaceous materials, sulfate, nitrate, and ammonium were the most important contributors to the PM10 component. On average, 64% of the PM10 was made up of fine particles. During PM10 episodes, average wind speed was 0.7 m/s and relative humidity was high, 83% on average, probably giving rise to stagnation of air pollutants and their entrapment close to the surface. With relative humidity70%, NO3-, NH4+, SO4(2-), carbonaceous materials, and PM10 mass showed high correlation with maximum hourly average ozone (O3M). Variation in atmospheric humidity may affect the gas-to-particle interactions of S and N species. The most significant contribution to PM10 in the Taichung urban basin was from the photochemical formation of secondary aerosols and carbonaceous materials in the atmospheric environment.