Effects of Particulate Matter Exposure on the Eustachian Tube and Middle Ear Mucosa of Rats.

OBJECTIVES: Particulate matter (PM) is a risk factor for various diseases. Recent studies have established an association between otitis media (OM) and PM exposure. To confirm this relationship, we developed a novel exposure model designed to control the concentration of PM, and we observed the effects of PM exposure on the Eustachian tube (ET) and middle ear mucosa of rats. METHODS: Forty healthy, 10-week-old, male Sprague-Dawley rats were divided into 3-day, 7-day, 14-day exposure, and control groups (each, n=10). The rats were exposed to incense smoke as the PM source for 3 hours per day. After exposure, bilateral ETs and mastoid bullae were harvested, and histopathological findings were compared using microscopy and transmission electron microscopy (TEM). The expression levels of interleukin (IL)-1ß, IL-6, tumor necrosis factor-α, and vascular endothelial growth factor (VEGF) in the middle ear mucosa of each group were compared using real-time reverse transcription polymerase chain reaction (RT-PCR). RESULTS: In the ET mucosa of the exposure group, the goblet cell count significantly increased after PM exposure (P=0.032). In the middle ear mucosa, subepithelial space thickening, increased angio-capillary tissue, and inflammatory cell infiltration were observed. Moreover, the thickness of the middle ear mucosa in the exposure groups increased compared to the control group (P<0.01). The TEM findings showed PM particles on the surface of the ET and middle ear mucosa, and RT-PCR revealed that messenger RNA (mRNA) expression of IL-1ß significantly increased in the 3-day and 7-day exposure groups compared to the control group (P=0.035). VEGF expression significantly increased in the 7-day exposure group compared to the control and 3-day exposure groups (P<0.01). CONCLUSION: The ET and middle ear mucosa of rats showed histopathologic changes after acute exposure to PM that directly reached the ET and middle ear mucosa. Therefore, acute exposure to PM may play a role in the development of OM.

Preliminary study on the effect of using heat-not-burn tobacco products on indoor air quality.

In this study, the effect of the use of heat-not-burn (HnB) products on indoor air quality (IAQ) was evaluated. To do this, the concentrations of nicotine, propylene glycol (PG), and vegetable glycerin (VG) directly emitted when using HnB products were analyzed and compared to those from conventional cigarettes. Furthermore, the levels of VOCs, aldehydes, nanoparticle, and particulate matter (PM) detected when subjects used HnB products in the exposure chamber were evaluated the effect on IAQ. As a result, the range of nicotine levels transferred by HnB products (0.8-1.2 mg cigarette-1) is lower than that by conventional cigarettes (2.4-3.6 mg cigarette-1). On the other hand, the range of VG levels emitted from HnB products (3.1-5.9 mg cigarette-1) were higher than that emitted from conventional cigarettes (0.6-3.0 mg cigarette-1). In addition, although the amount generated from HnB products was small compared to those from conventional cigarettes, various kinds of VOCs, aldehydes, nanoparticle and PM were produced, and these were confirmed to affect IAQ.

Volatile organic compounds released in the mainstream smoke of flavor capsule cigarettes.

In this study, the composition of mainstream smoke was investigated with an emphasis on a list of volatile organic compounds (VOCs: e.g., isoprene, acrylonitrile, methyl ethyl ketone, benzene, toluene, m-xylene and styrene) using the two types of flavor capsule cigarettes (FCCs, here coded as F1 and F2) in reference to one commercial, non-flavored (NF) and 3R4F cigarette. The concentrations of all the target compounds from FCCs were quantified under two contrasting conditions (i.e., with and without breaking the capsules). The effect of breaking the capsule was apparent in the FCC products with the enhancement of VOC levels, specifically between after and before breaking the capsules (e.g., 1.10-1.58 folds (benzene) and 1.30-1.53 folds (acetonitrile)). Such increases were apparent in both FCC samples if assessed in terms of the total amount of VOCs (TVOC): (1) F1 (from 2159 to 2530 µg cig-1 (p = 9.42 × 10-6)) and (2) F2 (from 1470 to 2014 µg cig-1 (p = 0.05)). In addition, these TVOC levels determined from the FCCs were 1.62- to 1.83- and 1.29- to 1.46-fold higher than those of the NF cigarette and the 3R4F cigarette, respectively. Thus, these FCC products are suspected to play a role as stronger sources of VOCs than the general cigarette products.

Decomposition of n-hexane using a dielectric barrier discharge plasma.

In this study, we investigated the decomposition characteristics of n-hexane by a dielectric barrier discharge (DBD) plasma. In order to accomplish this, the factors influencing these decomposition characteristics such as background gases (air, N2, and He), residence time (1-10 s), initial n-hexane concentration (10-50 ppm), relative humidity (2.5%, 40%, and 70%), and power (50-80 W) were evaluated. As a result, the decomposition efficiency of n-hexane at N2 atmosphere was found to be lower than those at air and He atmosphere. The removal efficiency of n-hexane was increased when the residence time, relative humidity, and power increased, and when the initial concentration decreased. The concentrations of CO, CO2, and aerosol increased as the specific energy density increased. However, the O3 level increased up to a certain point, then decreased. Various hydrocarbons such as acetone, pentanal, nonanal, etc. were also detected as by-products and their decomposition and recombination pathways were suggested.

A Potential Approach to Compensate the Gas Interference for the Analysis of NO by a Non-dispersive Infrared Technique.

Interference is a pivotal issue of a non-dispersive infrared (NDIR) sensor and analyzer. Therefore, the main contribution of this study is to introduce a potential method to compensate for the interference of the NDIR analysis. A potential method to compensate for the interference of a nitric oxide (NO) NDIR analyzer was developed. Double bandpass filters (BPFs) with HITRAN (high-resolution transmission molecular absorption database)-based wavelengths were used to create an ultranarrow bandwidth, where there were least-interfering effects with respect to the coal-fired power plant emission gas compositions. Key emission gases from a coal-fired power plant, comprising carbon monoxide (CO), NO, sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon dioxide (CO2), and water (H2O) (in the form of vapor), were used to investigate the gas interference. The mixtures of those gases were also used to investigate the performance of the double BPFs. We found that CO, CO2, SO2, and H2O significantly affected the detection of NO when a commercial, single narrow BPF was used. In contrast, the double BPFs could remove the interference of CO, NO2, SO2, and CO2 in terms of their concentrations. In the case of H2O, the filter performed well until a level of 50% relative humidity at 25 °C. Moreover, the signal-to-noise ratio of the analyzer was approximately 10 when the double BPFs were applied. In addition, the limit of detection of the analyzer with the double BPFs was approximately 4 ppm, whereas that with the commercial one was 1.3 ppm. Therefore, double BPFs could be used for an NO NDIR analyzer instead of a gas filter correlation to improve the selectivity of the analyzer under the condition of a known gas composition, such as a coal-fired power plant. However, the sensitivity of the analyzer would be decreased.

The effects of continuous- and stop-flow gas streams on adsorptive removal of benzene vapor using type - II covalent organic polymers.

Various materials have been investigated for the adsorptive removal of volatile organic compounds (VOCs, such as benzene). However, most materials proposed for the adsorptive removal of gaseous benzene (and other VOCs) perform relatively poorly (e.g., an impractically low-service 10% breakthrough volume [BTV10] at < 100 ppm). The adsorbent uptake rate (mg g-1 min-1) can also be assessed as a function of the gas-stream flow rate (or space velocity). The main aim of this study is to explore the effect of two different gas-stream supply modes - stopped flow (at a fixed stream flow rate of 330 mL atm min-1) vs. continuous flow (a variable-stream flow rate of 100, 200, or 330 mL atm min-1) on the adsorption metrics of gaseous benzene on 5 mg of two types of - II covalent organic polymers (COPs: CBAP-1 [DETA], CD; or CBAP-1 [EDA], CE). The sorbent tube outlet stream was sampled by two respective sampling methods (i.e., a large-volume injector [LVI] for stopped flow vs. syringe injection [SI] for continuous flow) for sample quantitation by gas chromatography flame-ionization detection (GC-FID). The observed BTV10 values in the two sampling modes were similar when tested using 10 ppm benzene, irrespective of sorbents: 56/60 (CD) vs. 620/624 L atm g-1 (CE). BTV10 values increased systematically with decreasing stream-flow rates to reflect the importance of space velocity in adsorptive removal of benzene. The overall assessment of adsorption performance between stopped flow (LVI) and continuous flow (SI) revealed that the performance of the adsorbent is independent of flow mode (e.g., when performance was compared at flow rate of 330 mL min-1).

Quantitative insights into major constituents contained in or released by electronic cigarettes: Propylene glycol, vegetable glycerin, and nicotine.

Generally, the liquid used in electronic cigarettes (E-cigarettes), which is also called E-liquid, is composed of propylene glycol (PG), vegetable glycerin (VG), and nicotine, with many other miscellaneous ingredients. E-liquid is consumed mainly in the form of aerosol via inhalation by the e-cigarette user. The amount and composition of the aerosol generated during its consumption depend on various factors. In this study, the three major constituents (PG, VG, and nicotine) of E-cigarettes were analyzed in both liquid and aerosol samples from 50 commercial products. Their concentrations in the liquid (and aerosol at 3.4 V) samples were 538 (4 6 7), 482 (4 4 9), and 8.75 mg g-1 (7.91 mg g-1), respectively. The nicotine levels in the E-liquids measured in this study were normally 1.2 times greater than those specified by the manufacturers. Furthermore, the amount of liquid consumed increased proportionally as the voltage of the E- cigarette increased. The consumption rate of VG increased as the voltage of the E-cigarette increased, whereas that of PG and nicotine decreased. The results of our study confirm that the amounts of PG and VG generated through the use of E-cigarettes are noticeably larger than those from other tobacco products (such as traditional tobaccos and heat-not-burn products), although no such trend was evident in case of nicotine.

An efficient tool for the continuous monitoring on adsorption of sub-ppm level gaseous benzene using an automated analytical system based on thermal desorption-gas chromatography/mass spectrometry approach.

It became an important task to effectively adsorb volatile organic compounds (VOCs) at or near real-world levels for efficient control of airborne pollution in ambient environments. Nonetheless, most studies carried out previously for the control of VOCs are confined to significantly polluted conditions (e.g., >100 ppm) that are far different from real-world or ambient conditions. To help acquire the meaningful data for the adsorptive removal of VOCs at near real-world levels, a new approach was designed and implemented to measure adsorption of gaseous benzene (as a representative or model VOC) at trace-level quantities (as low as 0.14 ng (0.43 ppb) for a 100 mL sample) using activated carbon (sieved to 212 µm mesh size) as a model sorbent. With the aid of a thermal desorption-gas chromatography/mass spectrometry system, the key adsorption performance metrics (such as 10% breakthrough volume (10% BTV) points: 10% as the key reference) were determined: 1018 L atm g-1 at 0.1 ppm benzene with the corresponding partition coefficient of 3.85 mol kg-1 Pa-1. If the adsorption capacity values (at 10% BTV) are compared across the varying concentration levels of benzene, the maximum value of 1.07 mg g-1 was observed at 1 ppm benzene (within the concentration range selected in this work). As such, it was possible to quantitatively assess the sorbate-sorbent interactions at significantly low concentrations of VOCs that actually prevail under the near real-world conditions.

Cardiac Autonomic Effects of Secondhand Exposure to Nicotine from Electronic Cigarettes: An Exploratory Study.

BACKGROUND: The rapid increase in prevalence of e-cigarette (EC) use may lead to widespread exposure to secondhand emissions among nonsmokers, but evidence on the potential cardiovascular health risks is limited. We aimed to investigate effect of short-term secondhand exposure to nicotine from e-cigarette (EC) emissions on cardiac autonomic function using heart rate variability (HRV). METHODS: A randomized, repeated measures crossover study of healthy nonsmoking volunteers was conducted. Standard deviation of NN intervals (SDNN), average of the standard deviation of NN intervals (ASDNN), root mean square of successive differences (rMSSD), and heart rate-corrected QT interval (QTc) were calculated during one hour of EC exposure session. RESULTS: Nicotine from EC emissions was associated with a 7.8% decrease in SDNN (95% CI, -11.2% to -4.3%), 7.7% decrease in ASDNN (95% CI, -11.0% to -4.2%) and 3.8 msec decrease in QTc (95% CI, -5.8 to -1.9). Compared with a short exposure time period (<15min), greater nicotine associated with reductions in ASDNN (P for interaction = 0.076) with longer exposure time periods. For QTc, greater nicotine associated with reductions were found during 15-30 min exposure time period (P for interaction = 0.04). CONCLUSION: We present the first evidence of cardiac autonomic effects of short-term secondhand exposure to nicotine from EC emissions among healthy nonsmokers. Further comprehensive research on EC exposure extending to more subjects and flavor compounds is warranted.

The transfer characteristics of heavy metals in electronic cigarette liquid.

In this research, the concentrations of six heavy metals (Zn, Pb, Ni, Fe, Cd, and Cr) in electronic cigarette (EC) solutions were determined to assess their association with EC use patterns. To this end, their contents were analyzed under three conditions: (1) ECL I: EC liquid was directly taken from EC liquid bottles as purchased from retail, (2) ECL II: EC liquid simply stored in the EC clearomizer for a certain period was collected without any puffing, and (3) ECL III: EC liquid remaining in the EC clearomizer after puffing. Each of all three types of electronic cigarette liquid (ECL) samples selected in this study was analyzed after being stored for up to seven days (at elapsed intervals of 1, 3, and 7 days). Zn and Pb were detected in all types of samples while Cd was all below method detection limit (MDL). Fe, Ni, and Cr were generally below MDL in ECL I, while it was not the case for ECL II and III samples. Especially, Zn, Pb, and Ni levels increased significantly with the use of EC. If the consumption of EC causes alterations in elemental content, such changes can be assessed in terms of ratio values such as "after/before use". The maximum ratio values for each target, when assessed using ECL III samples, were seen in the following order: 463 (Zn) > 315 (Ni) > 131 (Fe) > 47.9 (Cr) > 36.0 (Pb). As such, EC use is clearly demonstrated as the transfer route of heavy metals.

Development of a magnetic hybrid filter to reduce PM10 in a subway platform.

This study investigated the reduction of particulate matter (PM) in a subway platform using self-developed magnetic hybrid filters (magnet-magnet (MM) and magnet-cascade (MC) filter). The magnetic hybrid filter systems were installed and operated in Jegi-dong subway station (J station) platform. The removal efficiency of PM10 (particular matter with aerodynamic diameter less than 10 µm) was evaluated according to various influencing factors such as the combination of filters, linear velocity, and operating conditions of trains. As a result, the average removal efficiency of the MC filter (40.5%) was higher than that of the MM one (27.0%). The maximum PM10 removal efficiencies by MM (34.1%) and MC (47.2%) filters were observed at 20 (linear velocity: 2.41 m/s) and 30 jog (8 m/s) dials, respectively. We additionally found that the removal efficiency of PM10 using MM and MC filters suddenly decreased when the concentration of background PM10 in the platform increased. Based on the results of this study, hybrid technology using two or more capture principles can remove PM more efficiently than technology using a single such principle.

A review of traditional and advanced technologies for the removal of particulate matter in subway systems.

The pollution status of particulate matter (PM) in a subway system and technological trends in their reduction were discussed in this study. The levels of PM2.5 and PM10 are generally found to be higher in the underground platforms and tunnels than those in the outdoor air. It has also been reported that the composition of fine dust in the subway consists of various substances including heavy metals (like Fe), carbonaceous matter, and solvent extractable organic matter (SEOM). It was confirmed that subway dust was created mainly by wearing on wheels, rails, and brakes. In addition, the concentration of PM in such environment was influenced not only by internal factors (eg, operating conditions of trains and ventilation systems, number of passengers, and the structure of subway stations) but also by outside factors (eg, ambient air concentration). Up to now, various techniques (ventilation fans, platform screen doors (PSDs), magnetic filters, small jet fans, artificial intelligent ventilation systems, hybrid filters, etc) have been studied to reduce PM in underground subway systems. In this study, we reviewed the air quality of major subway stations with the focus on PM and relevant technologies for its reduction.

Nicotine, aerosol particles, carbonyls and volatile organic compounds in tobacco- and menthol-flavored e-cigarettes.

BACKGROUND: We aimed to assess the content of electronic cigarette (EC) emissions for five groups of potentially toxic compounds that are known to be present in tobacco smoke: nicotine, particles, carbonyls, volatile organic compounds (VOCs), and trace elements by flavor and puffing time. METHODS: We used ECs containing a common nicotine strength (1.8%) and the most popular flavors, tobacco and menthol. An automatic multiple smoking machine was used to generate EC aerosols under controlled conditions. Using a dilution chamber, we targeted nicotine concentrations similar to that of exposure in a general indoor environment. The selected toxic compounds were extracted from EC aerosols into a solid or liquid phase and analyzed with chromatographic and spectroscopic methods. RESULTS: We found that EC aerosols contained toxic compounds including nicotine, fine and nanoparticles, carbonyls, and some toxic VOCs such as benzene and toluene. Higher mass and number concentrations of aerosol particles were generated from tobacco-flavored ECs than from menthol-flavored ECs. CONCLUSION: We found that diluted machine-generated EC aerosols contain some pollutants. These findings are limited by the small number of ECs tested and the conditions of testing. More comprehensive research on EC exposure extending to more brands and flavor compounds is warranted.

Spatial Variability of AERONET Aerosol Optical Properties and Satellite Data in South Korea during NASA DRAGON-Asia Campaign.

We investigated spatial variability in aerosol optical properties, including aerosol optical depth (AOD), fine-mode fraction (FMF), and single scattering albedo (SSA), observed at 21 Aerosol Robotic Network (AERONET) sites and satellite remote sensing data in South Korea during the spring of 2012. These dense AERONET networks established in a National Aeronautics and Space Administration (NASA) field campaign enabled us to examine the spatially detailed aerosol size distribution and composition as well as aerosol levels. The springtime particle air quality was characterized by high background aerosol levels and high contributions of coarse-mode aerosols to total aerosols. We found that between-site correlations and coefficient of divergence for AOD and FMF strongly relied on the distance between sites, particularly in the south-north direction. Higher AOD was related to higher population density and lower distance from highways, and the aerosol size distribution and composition reflected source-specific characteristics. The ratios of satellite NO2 to AOD, which indicate the relative contributions of local combustion sources to aerosol levels, represented higher local contributions in metropolitan Seoul and Pusan. Our study demonstrates that the aerosol levels were determined by both local and regional pollution and that the relative contributions of these pollutions to aerosols generated spatial heterogeneity in the particle air quality.

Volatile organic compounds (VOCs) in surface coating materials: Their compositions and potential as an alternative fuel.

A sampling system was designed to determine the composition ratios of VOCs emitted from 31 surface coating materials (SCMs). Representative architectural, automotive, and marine SCMs in Korea were investigated. Toluene, ethylbenzene, and xylene were the predominant VOCs. The VOC levels (wt%) from automotive SCMs were significantly higher than those from architectural and marine paints. It was found that target SCMs comprised mainly VOCs with 6-10 carbon atoms in molecules, which could be adsorbed by activated carbon. The saturated activated carbon which had already adsorbed toluene, ethylbenzene, and m-xylene was combusted. The saturated activated carbon was more combustible than new activated carbon because it comprised inflammable VOCs. Therefore, it could be an alternative fuel when using in a "fuelization system". To use the activated carbon as a fuel, a control technology of VOCs from a coating process was also designed and introduced.

Development of an activated carbon filter to remove NO2 and HONO in indoor air.

To obtain the optimum removal efficiency of NO2 and HONO by coated activated carbon (ACs), the influencing factors, including the loading rate, metal and non-metal precursors, and mixture ratios, were investigated. The NOx removal efficiency (RE) for K, with the same loading (1.0 wt.%), was generally higher than for those loaded with Cu or Mn. The RE of NO2 was also higher when KOH was used as the K precursor, compared to other K precursors (KI, KNO3, and KMnO4). In addition, the REs by the ACs loaded with K were approximately 38-55% higher than those by uncoated ACs. Overall, the REs (above 95%) of HONO and NOx with 3% KOH were the highest of the coated AC filters that were tested. Additionally, the REs of NOx and HONO using a mixing ratio of 6 (2.5% PABA (p-aminobenzoic acid)+6% H3PO4):4 (3% KOH) were the highest of all the coatings tested (both metal and non-metal). The results of this study show that AC loaded with various coatings has the potential to effectively reduce NO2 and HONO levels in indoor air.

Emission characteristics of VOCs emitted from consumer and commercial products and their ozone formation potential.

The characteristics of volatile organic compounds (VOCs) emitted from several consumer and commercial products (body wash, dishwashing detergent, air freshener, windshield washer fluid, lubricant, hair spray, and insecticide) were studied and compared. The spray products were found to emit the highest amount of VOCs (~96 wt%). In contrast, the body wash products showed the lowest VOC contents (~1.6 wt%). In the spray products, 21.6-96.4 % of the VOCs were propane, iso-butane, and n-butane, which are the components of liquefied petroleum gas. Monoterpene (C10H16) was the dominant component of the VOCs in the non-spray products (e.g., body wash, 53-88 %). In particular, methanol was present with the highest amount of VOCs in windshield washer fluid products. In terms of the number of carbon, the windshield washer fluids, lubricants, insecticides, and hair sprays comprised >95 % of the VOCs in the range C2-C5. The VOCs in the range C6-C10 were predominantly found in the body wash products. The dishwashing detergents and air fresheners contained diverse VOCs from C2 to C11. Besides comprising hazardous VOCs, VOCs from consumer products were also ozone precursors. The ozone formation potential of the consumer and commercial spray products was estimated to be higher than those of liquid and gel materials. In particular, the hair sprays showed the highest ozone formation potential.

Installation of platform screen doors and their impact on indoor air quality: Seoul subway trains.

In this study, variations of particulate matter (PM) concentrations in subway trains following installation of platform screen doors (PSDs) in the Seoul subway system were investigated. PM samples were collected in the trains on subway lines 1-8 before and after installation of PSDs. It was found that the mean PM10 concentration in the trains after PSDs installation increased significantly by 29.9% compared to that before installation. In particular, the increase of PM10 in line 6 was the highest at 103%. When the relationship between PM10 and PM2.5 was compared, coefficients of determination (r2) before and after PSDs installations were 0.696 and 0.169, respectively. This suggests that air mixing between the platform and the tunnel after PSDs installation was extremely restricted. In addition, the indoor/outdoor PM10 ratio following PSDs installation increased from 1.32 to 2.97 relative to the period with no installed PSDs. Furthermore, this study revealed that PM levels in subway trains increased significantly after all underground PSDs were put in use. Several potential factors were examined that could result in this PM increase, such as train ventilation systems, operational conditions, passenger volume, subway depth, and the length of underground segments. Implications: PM10 concentrations inside the subway trains increased after PSDs installation. This indicates that air quality in trains was very seriously impacted by PSDs. PM10 levels were also influenced by the tunnel depth and length of the underground segments. To prevent the adverse effect on human health by PM10 emitted from the tunnel, an applicable ventilation system to reduce PM10 is required inside trains and tunnels.

Removal of particulate matter emitted from a subway tunnel using magnetic filters.

We removed particulate matter (PM) emitted from a subway tunnel using magnetic filters. A magnetic filter system was installed on the top of a ventilation opening. Magnetic field density was increased by increasing the number of permanent magnet layers to determine PM removal characteristics. Moreover, the fan's frequency was adjusted from 30 to 60 Hz to investigate the effect of wind velocity on PM removal efficiency. As a result, PM removal efficiency increased as the number of magnetic filters or fan frequency increased. We obtained maximum removal efficiency of PM10 (52%), PM2.5 (46%), and PM1 (38%) at a 60 Hz fan frequency using double magnetic filters. We also found that the stability of the PM removal efficiency by the double filter (RSD, 3.2-5.8%) was higher than that by a single filter (10.9-24.5%) at all fan operating conditions.

Development of a pretreatment system for the analysis of atmospheric reduced sulfur compounds.

A new pretreatment system was used to evaluate a technology to analyze reduced sulfur compounds (RSCs). To conduct this research, a self-developed custom dryer (Desolvator) and a thermal desorber system (TDS) were installed in the front of GC/PFPD. The syringe pump inside the TDS was devised in such a way that it can be desorbed in a relatively low desorption temperature and low vacuum (730 Pa). When comparing water removal efficiency of the Desolvator and frequently used Nafion dryer, the removal efficiency of the Desolvator stood between 94.6 and 96.1%, considerably higher and more stable than the Nafion dryer (81.3-94.5%). Moreover, analyses were made under various conditions in order to minimize the loss of samples when analyzing sulfur compounds using the TDS, and it was determined that adsorption temperatures less than -25 °C and a flow rate of 50 mL/min were appropriate for the efficient analysis of these sulfur compounds. Moreover, the desorption flow rate and the degree of a vacuum were found to be significant variables for the RSCs desorption. Besides, it was observed that a peculiar peak was formed by thermal decomposition when some sulfur compounds were rapidly desorbed at high desorption temperatures.