Air Quality Variation in Wuhan, Daegu, and Tokyo during the Explosive Outbreak of COVID-19 and Its Health Effects.

This study was designed to assess the variation of the air quality actually measured from the air pollution monitoring stations (AQMS) in three cities (Wuhan, Daegu, and Tokyo), in Asian countries experiencing the explosive outbreak of COVID-19, in a short period of time. In addition, we made a new attempt to calculate the reduced DosePM2.5 (µg) at the bronchiolar (Br.) and alveolar-interstitial (AI) regions of the 10-year-old children after the city lockdown/self-reflection of each city. A comparison of the average PM2.5 of a month before and after the lockdown (Wuhan) and self-reflection (Daegu and Tokyo) clearly shows that the PM2.5 concentration was decreased by 29.9, 20.9, and 3.6% in Wuhan, Daegu and Tokyo, respectively. Wuhan, Daegu and Tokyo also recorded 53.2, 19.0, and 10.4% falls of NO2 concentration, respectively. Wuhan, which had the largest decrease of PM2.5 concentration due to COVID-19, also marked the largest reduced DosePM2.510-year-old children (µg) (3660 µg at Br. and 6222 µg at AI), followed by Daegu (445 µg at Br. and 1,287 µg at AI), and Tokyo (18 µg at Br. and 52 µg at AI), over two months after the city lockdown/self-reflection. Our results suggest that the city lockdown/self-reflection had the effect of lowering the concentration of PM2.5, resulting in an extension of the period it took to the acute allergic airway inflammation (AAI) for the 10-year-old children.

Differences in agricultural activities related to incidence of scrub typhus between Korea and Japan.

OBJECTIVES: The purpose of this study was to establish a basis for improving or strengthening the preventive strategy against scrub typhus in Korea by comparing and analyzing the difference of prevention behaviors contributing to the occurrence of scrub typhus in Japan and Korea. METHODS: The survey was carried out in Jeollabuk-do, which is a high risk and high incidence area, and Fukuoka Prefecture, which is a high risk and low incidence area. The study included 406 Korean farmers and 216 Japanese farmers. Data were collected through face-to-face surveys by interviewers who had completed standardized education. RESULTS: Korean farmers have a higher percentage of agricultural working posture that involved contact with weeds than Japanese farmers (p<0.05). The frequency and proportion of weeding were lower in Korean farmers than in Japanese farmers (p<0.05). The level of knowledge about scrub typhus was significantly higher among Korean farmers than among Japanese farmers (p<0.05). Mostly, the behavior of agriculture work was more appropriate for Japanese farmers than for Korean farmers (p<0.05). The total average level of agricultural work was lower in Korea than in Japan, lower in men than women, and lower in part-time farmers than full-time farmers (p<0.05). CONCLUSIONS: This study suggests that it is reasonable to develop and provide a program that can improve the level of preventive behavior taking into consideration the characteristics of the subject in order to reduce the incidence of diseases in high-risk areas for scrub typhus.

Measurements of major VOCs released into the closed cabin environment of different automobiles under various engine and ventilation scenarios.

Volatile organic compounds (VOCs) in automobile cabins were measured quantitatively to describe their emission characteristics in relation to various idling scenarios using three used automobiles (compact, intermediate sedan, and large sedan) under three different idling conditions ([1] cold engine off and ventilation off, [2] exterior air ventilation with idling warm engine, and [3] internal air recirculation with idling warm engine). The ambient air outside the vehicle was also analyzed as a reference. A total of 24 VOCs (with six functional groups) were selected as target compounds. Accordingly, the concentration of 24 VOC quantified as key target compounds averaged 4.58 ± 3.62 ppb (range: 0.05 (isobutyl alcohol) âˆ¼ 38.2 ppb (formaldehyde)). Moreover, if their concentrations are compared between different automobile operational modes: the 'idling engine' levels (5.24 ± 4.07) was 1.3-5 times higher than the 'engine off' levels (4.09 ± 3.23) across all 3 automobile classes. In summary, automobile in-cabin VOC emissions are highly contingent on changes in engine and ventilation modes.

Ambient particulate matter in a central urban area of Seoul, Korea.

The concentrations of PM2.5 and PM10 were monitored at a central urban area of Yongsan (YS), Seoul, Korea during 2013. The daily average concentrations of both PM2.5 and PM10 fractions, were 26.6±12.6 and 45.0±20.4 µg m(-3), respectively. The observed PM2.5 concentration slightly exceeded the annual standard value (25 µg m(-3)) set by the Korean Ministry of Environment (KMOE), while that of PM10 was slightly lower than its guideline value (50 µg m(-3)). Comparison of the monthly mean values (µg m(-3)) of both PM fractions showed maximum concentrations in January (PM2.5: 36.9 and PM10: 59.7) and minimum concentrations in September (PM10: 28.1) and October (PM2.5: 14.9). The existence of strong correlations between the concentrations of PM and some gaseous pollutants (e.g., CO, SO2, and NOx) indicated the commonality of contributing source processes, such as traffic and industrial emissions. The results of a back-trajectory (BT) analysis also suggests that the PM pollution in the study area is likely to have been affected by many sources such as Asian dust, volcanic emissions, and industrial activities in the surrounding countries (China, Russia, and Japan).

An investigation into the relationship between the major chemical components of particulate matter in urban air.

Particulate matter (PM) generally comprises such chemical components as inorganic ions, organic carbon (OC), elemental carbon (EC), and metals. In terms of environmental studies, these major chemical components of particulate matter (MCP) are important in understanding PM distribution, behaviors and source apportionment. In this study, the MCP fractions of total suspended particles (TSP) were measured at an urban residential area in Seoul, Korea from February to December in 2009. The behavior of each individual MCP was studied in order to explain their relationship to environmental conditions and sources. The MCP measured during this study period was able to account between 54% (spring) to 67% (fall) of total TSP composition. During the study period, it was found that the TSP sampled comprised mostly: anions, OC, cations, EC, and metals in decreasing order of abundance. Although such relative ordering seems to remain fairly constant over time, the relative balance of this relationship may be altered by variations in environmental conditions.

A novel approach to identifying the elemental composition of individual residue particles retained in single snow crystals.

This study was carried out to describe the chemical characteristics of individual residual particles in hexagonal snow crystals, which can provide a clue to the aerosol removal mechanism during snowfall. In the present study, to collect snow crystal individually and to identify the elemental composition of individual residues retained in a hexagonal crystal, an orchestration of the replication technique and micro-particle induced X-ray emission (micro-PIXE) analysis was carried out. Information concerning the elemental compositions and their abundance in the snow crystals showed a severe crystal-to-crystal fluctuation. The residues retained in the hexagonal snow crystals were dominated primarily by mineral components, such as silica and calcium. Based on the elemental mask and the spectrum of micro-PIXE, it was possible to presume the chemical inner-structure as well as the elemental mixing state in and/or on the individual residues retained in single snow crystals.

Volatile Organic Compounds in Ambient Air at Four Residential Locations in Seoul, Korea.

To investigate the environmental behavior of volatile organic compounds (VOCs) in urban areas, their concentrations were measured at four urban monitoring sites (namely, N, S, E, and W) in Seoul, Korea (February to December 2009). A total of 27 compounds were quantified that consist of four chemical groups: aromatic (AR), halogenated aromatic, halogenated paraffin, and halogenated olefin. Results were evaluated by focusing on these four functional groups just mentioned and their summation term as total VOC (TVOC) along with several individual species (mainly AR species, that is, benzene, toluene, ethylbenzene, and xylene). The highest concentration of chemical groups was found from AR (71.1±42.1 ppbC), while that for individual species confirmed the dominance of toluene (7.48±3.88 ppb). The analysis of spatial distribution indicated that high TVOC levels were recorded at sites N and W, while it was not so significant such as S and E in terms of TVOC budget. Seasonal variation of these VOCs was characterized by the peak values in December to reflect the combined effects of pronounced source activities and meteorological conditions. Analysis of spatial variations in VOC levels between the four urban sites indicated that their distributions are tightly affected by local source processes in each area.

An analysis of long-term changes in airborne toxic metals in South Korea's two largest cities from 1991 to 2004.

BACKGROUND, AIM, AND SCOPE: Investigations on the temporal variabilities of metals generally show that the concentration levels of many harmful metals in air have been continuously decreasing around the world including North America and Western Europe. However, an excursion from such trends has been expected and demonstrated from E. Asia due to the major source contribution from China. To help understand long-term patterns of airborne toxic metals in East Asia, the particle-bound concentrations of Pb, Mn, Ni, Cr, and Cd were analyzed in the two largest cities of Korea, Seoul and Busan, over a 14-year period (1991 through 2004). The results of this study will provide a comprehensive overview on long-term trends of important metals in major urban areas of E. Asia. MATERIALS AND METHODS: This study was conducted to investigate the environmental behavior and long-term trends of toxic metals in Seoul and Busan, the two most populated cities of Korea, from 1991 to 2004. To this end, the concentrations of five toxic metals (including Pb, Cd, Cr, Mn, and Ni) in TSP (total suspended particle) fractions were measured by atomic absorption spectrometry. The analysis of long-term patterns of metal concentration data was conducted using two different temporal grouping criteria for both the full study period (1991-2004) and the second half (1998-2004). The statistical significance of such variabilities was assessed through a comparison with relevant reference data from other areas of the world. RESULTS: The annual mean concentration of the metals from the two cities was generally characterized by the lowest Cd (1.7-9.1 ng m(-3)) and largest Pb (51-341 ng m(-3)). The relative ordering of metal concentration levels from both cities was consistently found as: Pb > Mn > Ni > Cr > Cd. An evaluation of the absolute concentration levels showed that the values derived for both cities generally fell in an intermediate range between highly polluted (e.g., major Chinese cities) and moderately clean urban environments (Japanese or US sites). DISCUSSION: To help describe the long-term patterns of each metal, the metal concentration data between the two cities were compared in a number of respects. The results show strong compatibility with respect to relative trends between Seoul and Busan. When the long-term trends are compared for the entire study period (1991-2004), most metals tend to experience reductions in their concentrations through the years (with an exception of Cr), regardless of the city. The patterns were so distinctive that the statistical significance of this decline, if compared by the magnitude of probability in the regression analysis, generally increased in the order: Mn < Cd < Ni < Pb. A more detailed analysis of the temporal patterns (i.e., the second half of the study period (period II): 1998-2004), however, indicates that some metals reversed their trend to an increasing direction. For instance, Ni and Cr (both cities) and Mn (Seoul) showed an annual rate of change (ARC) in the range of 5.57 to 11.5%. However, others consistently maintained a declining trend with ARC values of -1.55 (Cd at Seoul) to -12.2% (Pb at Busan). CONCLUSIONS: According to the analysis of the long-term trend of trace metals, the efficiency of emission control appears to be highly complicated, as its effect is visualized to a certain extent. The patterns investigated in the two largest cities in Korea over a decadal period show that the reduction in concentration levels has been the most prominent and consistent for Pb but the least effective for Cr. Comparison among different studies and locations points out that changes in metal concentration levels, whether being an increase or decrease, should be tightly associated with the status of environmental pollution in the targeted area. RECOMMENDATIONS AND PERSPECTIVES: Evaluation of long-term monitoring data for toxic metals is helpful to judge various factors involved in regulation efforts and the response of those target pollutants. Future efforts are desirable to develop methods that allow a comparison of measurement data between the particle-filtrated samples and time-integrated environmental archives (bioaccumulation). Such efforts can provide the descriptive basis for explaining the environmental behavior of toxic metals at various time scales.

Analysis for chemical characterization of atmospheric aerosols application of X-ray microprobe system and double thin film method.

The X-ray microprobe system was applied to ultra trace characterization of single Kosa aerosols and non-Kosa aerosols simultaneously collected at Yasaka, Japan and TaeAnn, Korea. We demonstrated remarkable mass increase of heavy metals as well as soil components in individual particles during the Kosa event compared with the non-Kosa period at Yasaka. Backward trajectory analysis suggested that the Kosa samples were in the mixing state of mineral components and anthropogenic heavy elements. Double thin film method was applied to investigate the seasonal change of the mixing states of single sea-salt aerosols associated with chlorine loss due to the heterogeneous reactions between sea-salt particles and acidic gases. It was revealed that the percentages of both chloride-nitrate mixed particles and sulfate-nitrate ones were larger in wintertime than those in summertime and fraction of chloride-nitrate mixed particles increased with an increase of particle size. Comparison between the size-segregated bulk analysis and the single particle analysis demonstrated that remarkable chloride depletion occurred in coarse particles sampled on May in the former analysis, while chloride depletion in coarse particles was not marked in the latter analysis. The discrepancy attributes to the difference of the sampling time between both analyses because significant change of air mass route occurred during the bulk sampling after completion of the single particle sampling.

Elemental distribution in individual rain droplets determined by a combination of the replication method and the synchrotoron radiation X-ray fluorescence microprobe technique.

The main objective of the present study is to specify the chemical properties of individual rain droplets. For this purpose, we have combined the collodion replication method and the SR-XRF microprobe technique. The dry residual materials retained in a single rain droplet, which correspond to the former cloud condensation nuclei and the scavenged particles during droplet falling, were successively reconstructed by the multiple elemental maps using SR-XRF microprobe analytical system. Also the SR-XRF microprobe system allows us to quantify the masses of ultra trace elements in residues of individual rain droplet with fg level. The proposed combination method in the present study is found to be helpful to understand the physicochemical properties of individual rain droplets.