Aerosol and Air Quality Research
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社團法人台灣氣膠研究學會,正常發行
選擇卷期
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We collected ambient PM_(10) and PM_(2.5) samples from six sites in Tian'jin, China, from February to March 2016 and then analyzed their chemical compositions and identified the emission sources using the positive matrix factorization model. The mean concentrations of the PM_(10) and PM_(2.5) were 98 and 71 μg m^(-3), respectively, with a mean PM_(2.5)/PM_(10) ratio of 0.67. The average concentrations of the combined SO_4^(2-), NO_3^-, and NH_4^+ were 19.9-23.4 μg m^(-3), accounting for 72.4-77.1% of the total measured ions. The concentrations and percentages were significantly higher for NO_3^- and OC than for other species. The SO_4^(2-)/NO_3^- ratio showed a decreasing tendency as the PM_(10) and PM_(2.5) concentrations increased, implying a strong influence from mobile sources. The mean OC/EC ratios for PM_(10) and PM_(2.5) were 3.1 and 3.2, respectively, with small spatial differences. The most abundant elements were crustal, accounting for 73.2-84.2% of the total detected elemental mass, and mainly enriched in the PM_(10). The optimal number of factors for PM_(2.5) and PM_(10) was selected via PMF analysis: the decrease in the Q/Q_(except) values of these two fractions lessened when choosing six instead of five factors, indicating that five factors may be optimal. All the factors were mapped in bootstrap (BS) for 100% of the runs, and no swaps occurred with the displacement of factor elements (DISP) for five factors. Secondary inorganic aerosol, coal combustion, crustal dust, vehicle exhaust, and biomass burning contributed 28-30%, 20-21%, 18-21%, 17-20%, and 4%, respectively. Secondary inorganic aerosol displayed less spatial heterogeneity than the other sources in its contributions. Backward trajectory and PSCF analysis showed that air masses affecting Tian'jin mainly originated in the northwest during the heating period, and northeastern He'nan, southwestern Shan'dong, Bei'jing, and Tian'jin itself were major potential source areas.
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Air pollution is a crucial contributor to premature mortality and health problems. The excessive inhalation of fine particulate matter (PM_(2.5)) is strongly associated with adverse health effects due to its capability to penetrate deep into the human respiratory system. This study aimed to analyze the seasonal cycles of 24 h average PM_(2.5) mass concentrations in a suburban area in the southern region of Peninsular Malaysia. The meteorological variables and PM_(2.5) data were obtained via a Grimm Environmental Dust Monitor from August 2017 until January 2018. The maximum 24 h mass concentration was 44.6 μg m^(-3), with a mean value of 21.85 μg m^(-3), which was observed during the southwest monsoon. 43.33% and 8.33% of the daily concentrations exceeded the 24 h World Health Organization Guideline and Malaysian Ambient Air Quality Standard, respectively. The variation in the PM_(2.5) mass ranged between 0.53 and 0.90 times of the PM_(10) mass, indicating that the PM_(2.5) consistently contributed 52-92% of the PM_(10) mass concentration. During the monsoon seasons, the ambient temperature exhibited a significant positive correlation (p ＜ 0.05) with the PM_(2.5) mass concentration (r = 0.425-0.541), whereas the wind speed (r = -0.23 to -0.0127) and the relative humidity (r = -0.472 to -0.271) displayed strong negative correlations with it. Additionally, the rainfall was weakly correlated with the mass concentration. The presence of northeasterly wind at the study site suggests that the PM_(2.5) originated from sources to the northeast, which are influenced by anthropogenic activities and high traffic.
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The Beijing-Tianjin-Hebei region, characterized by frequent episodes of severe haze pollution during winter, is recognized as one of the key regions requiring air pollution control. To reduce the effects of severe pollution, early warning and emission reduction measures should be executed prior to these haze episodes. In this study, the efficacy of emission reduction procedures during severe pollution episodes was evaluated using the Weather Research and Forecasting model coupled with chemistry (WRF-Chem). To provide feedback and optimize emergency emission reduction plans, a pollution episode that occurred during the period of December 20-26, 2015, which was characterized by a high warning level, long warning period, and integrated pollution process, was selected as a case study to determine the influence of meteorological conditions and the effects of mitigation measures on heavy haze pollution episodes. Adverse meteorological conditions were found to increase PM_(2.5) concentrations by approximately 34% during the pollution episode. Moreover, the largest contributor to the episode was fossil fuel combustion, followed by dust emission and industrial processes; the first two factors play a significant role in most districts in Tianjin, whereas the third more strongly affects the adjoining districts and Binhai District. Emission reduction for industrial sources and domestic combustion more obviously decreases PM_(2.5) concentrations during the pollution dissipation stage than the pollution accumulation stage. Thus, different mitigation measures should be adopted in different districts and during different pollution stages. An approximate decrease of 18.9% in the PM_(2.5) concentration can be achieved when an emergency plan is implemented during the red alert period for heavy haze pollution episodes.
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Asian megacities are undergoing rapid population and infrastructure growth, which is resulting in significant air quality problems linked to atmospheric fine particles (PM_(2.5)). This study focuses on characterizing carbonaceous aerosols in an urban area of Bangkok, Thailand. The Microclimate and Air Pollutants Monitoring tower is located on the edge of Kasetsart University campus and was used to perform vertical measurements. Mass concentration data were collected using area dust monitors (ADR1500) at different levels above the ground (30 m, 75 m, and 110 m) during two time periods, daytime (08:00-19:00) and nighttime (20:00-07:00), throughout the monsoon season in 2015. All relevant micrometeorological parameters were simultaneously monitored. Backward air mass trajectories were calculated using HYSPLIT to assess the possible external pollution contributions. The thermal optical transmittance (TOT) method following the NIOSH 870 protocol was used to determine amounts of elemental carbon (EC) and organic carbon (OC) in samples. A data analysis showed average PM_(2.5) values at observation heights of 30 m, 75 m, and 110 m of 6.21 ± 2.45, 8.12 ± 3.65, and 9.03 ± 3.93 μg m^(-3), respectively; corresponding OC concentrations of 4.13 ± 2.65, 4.01 ± 4.07, and 4.11 ± 3.58 μg m^(-3), respectively, and EC concentrations of 1.02 ± 0.84, 1.07 ± 0.95, and 0.50 ± 0.70 μg m^(-3), respectively. The results show distinct gradients of increasing concentrations of PM_(2.5) with increasing elevation in contract with the OC and EC concentrations which decrease with height.
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In this study, the concentration and size distribution of fine dust particles were analyzed by measuring the dust in air generated during the cleaning of an indoor office. We measured the PM_(10), PM_(2.5), and PM_(1.0) and analyzed the size distributions of particles larger than 0.3 μm in diameter during cleaning. The results showed that the concentration of PM_(10) increased rapidly during cleaning, whereas the PM_(1.0) did not increase. Prior to sweeping the floor with a broom, the fine dust concentration was ~50 μg m^(-3), but it increased to ~400 μg m^(-3) as the sweeping progressed. When a vacuum cleaner was used, the concentration of PM_(10) increased, but the increase in PM_(2.5) was relatively small. As in the case of sweeping, the PM_(1.0) did not increase while vacuuming.
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Phenols and phthalates (PAEs) are always linked with the formation of secondary organic aerosols (SOA), while the water soluble ions (WSIs) are connected to the formation of secondary inorganic aerosols (SIA). A total of PM_(2.5) associated 20 phenols, 6 phthalates, and 9 WSIs were detected using GC-MS, ICS-1100, ICP-OES, and UV-VIS spectrophotometer for 5 stationary incineration sources including the domestic garbage (DG), garbage-fired power plant (GFPP), workshop of cable combustion for metal reclamation (WCC), peanut straw (PS), and wheat straw (WS). The anion equivalent (AE) and cation equivalent (CE) concentrations indicated that the emitted PM_(2.5) was alkaline for all the 5 combustion sources. Cl- possessed high contents among all the 5 burning sources and the highest value occurred at WCC due to the high Cl content in PVC. The WSI profiles were different from each other for the 5 incineration sources on the basis of high coefficients of divergence (CDs). The mass contributions of 9 WSIs in PM_(2.5) from 5 sources were far lower than those of atmospheric PM_(2.5). DEHP and DBP dominated in PM_(2.5) from 4 sources, while WCC possessed high levels of DEHP, DNOP, and DBP. WCC possessed the highest daily intakes of PAEs due to its highest Σ6PAEs of 32000 ng g^(-1) resulted from the high usage of plasticizers in PVC. The PAE profile similarities were found for both GFPP vs. DG and PS vs. WS based on low CDs. Only 11 phenols were detected for the 5 sources and WCC possessed the highest level of phenols although only phenol was detected. WS had the high levels of phenols due to the using of phenolic pesticides during wheat growth process.
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Nowadays, the airborne fungal spores have always taken an important role in the spread of crop fungal diseases and caused great concern. In this study, a novel efficient microfluidic chip for enriching the airborne fungal spores directly from gas flow was developed, which has better portability and cost-efficiency. The chip consists of three parts: half-wave pretreatment channel, inertial impactor, and low-pressure collection chamber. During the collection process, the particles were arranged in the radial position of the half-wave pretreatment channel based on their sizes, then separated by the inertial impactor and collected in the low-pressure collection chamber. The size distribution of the collected target was calculated by image process and recognition. The results show that the cut-off sizes of the proposed microfluidic device was found to be 4.83 μm (first-stage) and 0.98 μm (second-stage), respectively. The sharpness of the first and the second-stage collection efficiency curves were 1.31 and 1.79 respectively. The bounce effects and re-entrainment of particles can be eliminated by the low-pressure collection chamber without any silicon oil or grease. The collection reproducibility is acceptable. As a result, the proposed microfluidic chip can realize the crop fungal spore collection efficiently and can be used to improve the development of real-time crop fungal diseases monitoring technology.
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We developed two types of high performance nanofiber filters by increasing the uniformity of the fiber layer's deposition on the substrate media and by fabricating nanofiber with a branched morphology, in which additional fibers were spun to radiate from the main fibers. We subsequently compared them with conventional and beaded nanofiber filters in terms of particle removal efficiency, filter pressure drop, and particle loading capacity. First, the uniformity of the nanofiber's deposition, which was visually evaluated using optical and electron microscopes, was increased by removing the substrate surface charge during electrospinning. The uniform nanofiber filters demonstrated a higher filtration efficiency with a lower pressure drop than their conventionally electrospun counterparts, which exhibited irregular fiber layers. Second, branched nanofiber was fabricated by adjusting the viscosity of the polymer solution. The performance of the nanofiber filters was dramatically improved by the decrease in air flow resistance, which resulted from (1) a longer distance streamwise between the fibers and (2) a smaller diameter for the fibers. The enhanced efficiency was also due to (3) the additional fibers branching out from the main fibers.
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Particulate matter (PM) and other air pollutants are reportedly associated with both lung and systemic inflammation; however, an association between air pollutants and pneumonia outcomes has not been well established. Therefore, we evaluated the effect of air pollutants on the short-term outcomes of emergency department patients with pneumonia. We collected data on PM_(2.5) (aerodynamic diameter ＜ 2.5 μm), PM_(10) (aerodynamic diameter ＜ 10 μm), sulfur dioxide (SO_2), nitrogen dioxide (NO_2), and ozone from 11 air-quality monitoring stations in Kaohsiung City between January 1, 2008, and December 31, 2013. Medical records were extracted for non-trauma patients aged ＞ 17 years who had visited the emergency department with a principal diagnosis of pneumonia. In-hospital mortality and the association of air pollutant exposure with the need for invasive respiratory and/or vasopressor support (IRVS) within 72 h were evaluated. Interquartile range (IQR) increments of PM_(2.5) and PM_(10) were associated with an increased IRVS risk with odds ratios (ORs) of 1.211 (95% confidence interval [CI], 1.031-1.419) and 1.194 (95% CI, 1.020-1.394) on lag 1, respectively, and per-IQR increments of NO_2 were associated with an increased IRVS risk with an OR of 1.146 (95% CI, 1.004-1.308) on lag 2. IQR increments of PM_(2.5) and NO_2 were associated with an increased in-hospital mortality risk with ORs of 1.202 (95% CI, 1.100-1.429) and 1.175 (95% CI, 1.014-1.360), respectively. During the warm season, IQR increments of PM_(2.5), PM_(10), and NO_2 corresponded with an increased IRVS risk, with ORs of 1.333 (95% CI, 1.078-1.644), 1.348 (95% CI, 1.090-1.665), and 1.321 (95% CI, 1.101-1.585), respectively. For patients with pneumonia, PM_(2.5), PM_(10), and NO_2 exposures were risk factors for a poor prognosis. Exposure effects appeared to be greater during the warm season. Regulations focused on PM_(2.5), PM_(10), and NO_2 levels should be considered to improve patient outcomes.
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The composition characteristics and health risks of volatile organic compounds (VOCs) and their effects on secondary organic aerosol (SOA) during polluted and clean periods in winter 2018 for Yuncheng, a typical city in North China, were studied. The average concentration of VOCs was 2.3 times higher during the polluted period (105.29 μg m^(-3)) than the clean period (45.78 μg m^(-3)), whereas the average concentrations of the alkanes, alkenes, and aromatics were 3.4, 2.1, and 3.9 times higher, respectively, during the polluted period than the clean period. In addition, the VOC concentration was significantly influenced by meteorological conditions. Using positive matrix factorization (PMF), seven sources of atmospheric VOCs were identified, with the largest factors being vehicle emission (27.89%), coal combustion (23.37%), liquefied petroleum gas/natural gas evaporation (18.30%), and industrial emission (15.51%). Vehicle emission (30.04%) was the primary contributor during the polluted period, whereas coal combustion (33.53%) was the primary contributor during the clean period. The SOA formation potential (which almost exceeded 80%) was influenced by industrial emission (28.80%), solvent usage (26.30%), and vehicle emission (24.85%). Additionally, an assessment of the health risks of six aromatics based on the health risk exposure model of the United States Environmental Protection Agency revealed that the non-cancer risk was higher during the polluted period (6.61 × 10^(-2)) than the clean period (2.20 × 10^(-2)) but still below the Environmental Protection Agency (EPA) limit (1.00) and therefore negligible for the exposed population. However, the carcinogenic index of benzene (2.85 × 10^(-5) to 5 × 10^(-5)) exceeded 10^(-6), suggesting a higher carcinogenic risk. Large-scale energy restructuring during recent years has sharply reduced coal combustion, but the VOC concentration has dramatically increased due to vehicle emission. Hence, regulating vehicle emissions is an effective strategy for controlling VOCs in Yuncheng.