The effects of particle-induced oxidative damage from exposure to airborne fine particulate matter components in the vicinity of landfill sites on Hong Kong

The physical, chemical and bioreactivity characteristics of fine particulate matter (PM2.5) collected near (<1 km) two landfill sites and downwind urban sites were investigated. The PM2.5 concentrations were significantly higher in winter than summer. Diurnal variations of PM2.5 were recorded at both landfill sites. Soot aggregate particles were identified near the landfill sites, which indicated that combustion pollution due to landfill activities was a significant source. High correlation coefficients (r) implied several inorganic elements and water-soluble inorganic ions (vanadium (V), copper (Cu), chloride (Cl−), nitrate (NO3−), sodium (Na) and potassium (K)) were positively associated with wind flow from the landfill sites. Nevertheless, no significant correlations were also identified between these components against DNA damage. Significant associations were observed between DNA damage and some heavy metals such as cadmium (Cd) and lead (Pb), and total Polycyclic Aromatic Hydrocarbons (PAHs) during the summer. The insignificant associations of DNA damage under increased wind frequency from landfills suggested that the PM2.5 loading from sources such as regional sources was possibly an important contributing factor for DNA damage. This outcome warrants the further development of effective and source-specific landfill management regulations for particulate matter production control to the city

Spatial distributions of airborne di-carbonyls in urban and rural areas in China

Gaseous glyoxal and methylglyoxal concentrations were characterized in nine cities of China during 2010-2011. The average summer (winter) glyoxal and methylglyoxal concentrations were 36.4-178.4 (12.3-241.4) and 67.8-359.4 (28.4-530.0) ng/m(3), respectively. In summer, the highest average glyoxal concentration was in Guangzhou (GZ), while the lowest was in Shanghai (SH). In winter, Xiamen (XM) showed the highest average methylglyoxal concentration and Yantai (YT) reported the lowest. Both di-carbonyls showed distinct seasonal variations. The maximum average methylglyoxal concentration was approximately twice as much as glyoxal, which is consistent with the results of other studies. Glyoxal-to-methylglyoxal ratios showed that there was a consistent direct source of emissions in remote areas such as Qinghai Lake and Lhasa in both seasons (r &gt;= 0.9). Pearson&#39;s correlation analysis suggested possible similar sources formation (R &gt;= 0.7) for the two di-carbonyls in winter. Multiple linear regression analyses demonstrated that every 1 degrees C temperature increase could lead to a &gt; 2% increase in the concentration of the di-carbonyls in both seasons. There was a greater percentage gain for glyoxal in winter than in summer for the same temperature increase. The northeast monsoon occurs in winter, and for every 1 ms(-1) increase in wind speed, &gt;20% of the di-carbonyls can be transferred out of China. This study is useful to understand about the secondary organic aerosol formation in the areas, the statistical analysis can provide information about the relationships between these carbonyls in atmosphere. (C) 2016 Elsevier B.V. All rights reserved

Challenges on field monitoring of indoor airquality in china

Field monitoring is critical in the examination of indoor air quality (IAQ) which offers an integrated assessment of human exposure. A good measurement protocol includes appropriate methodologies and compliance of quality control and quality assurance procedures. In China, there has been a huge economic growth in the past 20 years and living standard for Chinese citizens has been improving with a rapid development in urban cities and infrastructures. With these developments, there have been a growth of increasing pollution sources, and IAQ has been a major concern to the government and many Chinese citizens with widespread reports of the coherent health impacts. However, the indoor monitoring in China is full of technical challenges. In this paper, we review the difficulties in conducting IAQ assessment in China. Techniques and practical consideration have been proposed accordingly

Seasonal behavior of carbonyls and source characterization of formaldehyde (HCHO) in ambient air

Gas-phase formaldehyde (HCHO) is an intermediate and a sensitive indicator for volatile organic compounds (VOCs) oxidation, which drives tropospheric ozone production. Effective photochemical pollution control strategies demand a thorough understanding of photochemical oxidation precursors, making differentiation between sources of primary and secondary generated HCHO inevitable. Spatial and seasonal variations of airborne carbonyls based on two years of measurements (2012-2013), coupled with a correlation-based HCHO source apportionment analysis, were determined for three sampling locations in Hong Kong (denoted HT, TC, and YL). Formaldehyde and acetaldehyde were the two most abundant compounds of the total quantified carbonyls. Pearson&#39;s correlation analysis (r &gt; 0.7) implies that formaldehyde and acetaldehyde possibly share similar sources. The total carbonyl concentration trends (HT &lt; TC &lt; YL) reflect location characteristics (urban &gt; rural). A regression analysis further quantifies the relative primary HCHO source contributions at HT (similar to 13%), TC (similar to 21%), and YL (similar to 40%), showing more direct vehicular emissions in urban than rural areas. Relative secondary source contributions at YL (similar to 36%) and TC (similar to 31%) resemble each other, implying similar urban source contributions. Relative background source contributions at TC could be due to a closed structure microenvironment that favors the trapping of HCHO. Comparable seasonal differences are observed at all stations. The results of this study will aid in the development of a new regional ozone (O-3) control policy, as ambient HCHO can enhance O-3 production and also be produced from atmospheric VOCs oxidation (secondary HCHO). (C) 2016 Elsevier Ltd. All rights reserved

Indoor, outdoor, and personal exposure to PM2.5 and their bioreactivity among healthy residents of Hong Kong

Direct evidence about associations between fine particles (PM2.5) components and the corresponding PM2.5 bioreactivity at the individual level is limited. We conducted a panel study with repeated personal measurements involving 56 healthy residents in Hong Kong. Fractional exhaled nitric oxide (FeNO) levels were measured from these subjects. Out of 56 subjects, 27 (48.2%) participated in concurrent outdoor, indoor, and personal PM2.5 monitoring. Organic carbon (OC), elemental carbon (EC), particle bound-polycyclic aromatic hydrocarbons (PAHs), and phthalates were analyzed. Alteration in cell viability, lactic dehydrogenase (LDH), interleukin-6 (IL-6), and 8-isoprostane by 50 mu g/mL PM2.5 extracts was determined in A549 cells in vitro. Moderate heterogeneities were shown in PM2.5 exposures and the corresponding PM2.5 bioreactivity across different sample types. Associations between the analyzed components and PM2.5 bioreactivity were assessed using the multiple regression models. Toxicological results revealed that indoor and personal exposure to OC as well as PAH compounds and their derivatives (e.g., Alkyl-PAHs, Oxy-PAHs) induced cell viability reduction and increase in levels of LDH, IL-6, and 8-isoprostane. Overall, OC in personal exposure played a dominant role in PM2.5-induced bioreactivity. Subsequently, we examined the associations of FeNO with IL-6 and 8-isoprostane levels using mixed-effects models. The results showed that per interquartile change in IL-6 and 8-isoprostane were associated with a 6.4% (p < 0.01) and 11.1% (p < 0.01) increase in FeNO levels, respectively. Our study explored the toxicological properties of chemical components in PM2.5 exposure, which suggested that residential indoors and personal OC and PAHs should be of great concern for human health. These findings indicated that further studies in inflammation and oxidative stress-related illnesses due to particle exposure would benefit from the assessment of in vitro PM2.5 bioreactivity

Unsuitability of using the DNPH-coated solid sorbent cartridge for determination of airborne unsaturated carbonyls

Measurements of aldehydes and ketones are typically conducted by derivatization using sorbent cartridges coated with 2,4-dinitrophenylhydrazine (DNPH). The collected samples are eluted with acetonitrile and analyzed by high-pressure liquid chromatography coupled with an ultra-violet detector (HPLC/UV). This paper intends to examine artifacts about its suitability in identification of unsaturated carbonyls. Kinetic tests for acrolein, crotonaldehyde, methacrolein and methyl vinyl ketone (MVK) showed formations of carbonyl-DNP-hydrazone during sampling, which could further react with DNPH, resulting in undesired UV absorption products [e.g., carbonyl-DNP-hydrazone-DNPH (dimer) and 2 (carbonyl-DNP-hydrazone)-DNPH (trimer)]. The dimerization and trimerization occurred for acrolein and MVK whereas only dimerization for crotonaldehyde and methacrolein. The polymerization products undoubtedly affect the integrity of the chromatogram, leading to misidentification and inaccurate quantification. Whether precautions taken during sampling and/or sample treatment could avoid or minimize this artifact has not been thoughtfully investigated. More often, such artifacts are usually overlooked by scientists when the data are reported.</p

Characteristics of carbonaceous aerosol in PM2.5: Pearl Delta RiverRegion, China

Simultaneous measurements of atmospheric organic carbon (OC), elemental carbon (EC) and water-soluble organic carbon (WSOC) were made at four sampling sites, namely Guangzhou (GZ), Zhaoqing (ZQ), PolyU Campus (PU) and Hok Tsui (HT), in the Pearl River Delta (PRD) region between 14 August 2006 and 28 August 2007. The highest concentrations of total carbon (TC) were found at the medium-scale roadside site (PU) and the lowest were found at the regional-scale site (HT). Among the four sampling sites, the average WSOC at ZQ showed the highest concentrations, while the lowest were seen at HT. OC and EC concentrations revealed spring/summer minima and autumn/winter maxima at all sites except PU, which had a consistently high EC concentration all over the year. The highest WSOC/OC ratio was found at ZQ with an average of 0.41, suggesting that the OC was more oxidized in the atmosphere of the semi-rural site. The lowest WSOC/OC was found at the roadside site of PU. Moreover, the WSOC/OC ratio increased in autumn, when the photochemical reactions are the most active in the PRD region. This can be attributed to aging and atmospheric processing of the organic compounds during their transportation, or to the formation of secondary organic aerosol (SOA). Average annual secondary organic carbon (SOC) concentrations in PM2.5 were estimated to be 2.2 and 3.5 &mu;g m&minus;3 for GZ and ZQ, comprising 33.5% and 42.8% of the corresponding OC concentrations, respectively. The results indicate that SOC is significant in the PRD region, and its formation mostly occurs within the region.</p

Chemical characteristics of PM2.5 and organic aerosol source analysis during cold front episodes in Hong Kong, China

In this study, we investigate the influence of long-range transport (LRT) episodes brought in by cold front on the concentration levels of PM2.5, major aerosol constituents, organic tracers, and PM2.5 source characteristics in Hong Kong, China. PM2.5 samples were collected during January&ndash;March 2004 and January&ndash;March 2005 and analyzed for major constituents and organic tracer species. Synoptic weather conditions and characteristics of common air pollutants were used to categorize the sampling days to three groups, i.e., groups mainly affected by local emissions or regional transport (RT) or cold front LRT. Concentrations of PM2.5 mass and its major constituents during cold-front days were lower than those during RT-dominated periods but higher than those during local emissions-dominated periods. Source apportionment using chemical mass balance (CMB) indicates that vehicular exhaust was a significant primary OC source of mainly local emissions, making average contributions of 1.82, 1.50, and 2.39 &mu;g C m&minus; 3 to OC in the local, LRT, and RT sample groups, respectively. During cold front periods, primary OC concentrations attributable to biomass burning and coal combustion were approximately triple and double, respectively, those during periods dominated by local emissions. Suspended dust, a minor primary OC source (0.24&ndash;0.40 &mu;g C m&minus; 3), also showed increased contribution during cold fronts. The unexplained OC by CMB (i.e., total OC minus apportioned primary OC), an approximate indicator for secondary OC, was a significant fraction of OC (&gt; 48%) and its mass concentration was much higher in the cold front LRT and RT sample groups (6.37 and 9.48 &mu;g C m&minus; 3) than in the local sample group (3.8 &mu;g C m&minus; 3). Source analysis as well as tracer concentration variation shows that biomass burning OC and water soluble organic carbon (WSOC) were correlated, suggesting biomass burning as a significant contributor to WSOC.</p

Characteristics of carbonate carbon in PM2.5 in a typical semi-arid area of Northeastern China

Daily concentrations of carbonate carbon (CC) in PM(2.5) collected in semi-arid area in Northeast China (Tongyu) were quantified by acidification that measures carbon dioxide (CO(2)) gas evolved using DRI Model 2001 Thermal Optical reflectance (TOR) Carbon Analyzer. The concentrations of CC during Asian dust storm (DS) and non-dust storm (NDS) periods during 14 April to 21 June, 2006 were determined and the transport pathways and possible sources for the CO(3)(2-) aerosols were identified. Concentrations of CC in PM(2.5) collected from 14 April to 23 June, 2006 in Tongyu are ranged from 0.1 to 7.5 mu gC m(-3) with an average of 1.3 mu gC m(-3). The average CC concentration during DS events was 2.6 +/- 1.7 mu g m(-3), which was almost 4 times the daily average concentration of 0.6 +/- 0.5 mu g m(-3) during non-dust storm (NDS) period. Carbonate carbon accounted for 10% and 4% of total carbon in Tongyu during DS and NDS period, respectively. Carbonate concentrations were also derived by calculating the difference between cations and anions (ionic balance method). And good correlation is observed for the carbonate measured to the values for carbonate calculated from the ionic balance difference (R(2) = 0.90). Higher correlations were observed between Ca with selected water-soluble ions (sulfate, nitrate or chloride) and elemental carbon in DS than in NDS periods. This is consistent with previous studies that more calcium salts (sulfate, nitrate or chloride) were formed during atmospheric transport during DS period. During the DS in spring 2006, three groups (A to C) of air mass trajectories were identified that passed over Tongyu. In general, when the air mass came from northwest, and south or southwest to Tongyu, high concentrations of carbonate were observed.</p

Microscale spatial distribution and health assessment of PM2.5-boundpolycyclic aromatic hydrocarbons (PAHs) at nine communities inXi'an, China

Spatial variability of polycyclic aromatic hydrocarbons (PAHs) associated with fine particulate matter (PM2.5) was investigated in Xi&#39;an, China, in summer of 2013. Sixteen priority PAHs were quantified in 24-h integrated air samples collected simultaneously at nine urban and suburban communities. The total quantified PAHs mass concentrations ranged from 32.4 to 104.7&nbsp;ng&nbsp;m&minus;3, with an average value of 57.1&nbsp;&plusmn;&nbsp;23.0&nbsp;ng&nbsp;m&minus;3. PAHs were observed higher concentrations at suburban communities (average: 86.3&nbsp;ng&nbsp;m&minus;3) than at urban ones (average: 48.8&nbsp;ng&nbsp;m&minus;3) due to a better enforcement of the pollution control policies at the urban scale, and meanwhile the disorganized management of motor vehicles and massive building constructions in the suburbs. Elevated PAH levels were observed in the industrialized regions (west and northwest of Xi&#39;an) from Kriging interpolation analysis. Satellite-based visual interpretations of land use were also applied for the supporting the spatial distribution of PAHs among the communities. The average benzo[a]pyrene-equivalent toxicity (&Sigma;[BaP]eq) at the nine communities was 6.9&nbsp;&plusmn;&nbsp;2.2&nbsp;ng&nbsp;m&minus;3 during the sampling period, showing a generally similar spatial distribution to PAHs levels. On average, the excess inhalation lifetime cancer risk derived from &Sigma;[BaP]eq indicated that eight persons per million of community residents would develop cancer due to PM2.5-bound PAHs exposure in Xi&#39;an. The great in-city spatial variability of PAHs confirmed the importance of multiple points sampling to conduct exposure health risk assessment.</p