Information on the work-time exposure of public bus and taxicab drivers to volatile organic compo... more Information on the work-time exposure of public bus and taxicab drivers to volatile organic compounds (VOCs) may be a critical factor in exploring the association between occupational exposure and health effects. Accordingly, this study evaluated the work-time VOC exposure of public bus and taxicab drivers by measurement of six selected aromatic VOC concentrations in the personal air of public
bus and taxicab drivers during winter and summer. Two groups of Ave public bus drivers (smokers and nonsmokers) and two groups of Ave taxicab drivers (smokers and nonsmokers) were recruited for the study. The taxicab drivers were found to be exposed to higher aromatic compound levels than the bus drivers during their daily work time. The personal exposure of the bus and taxicab drivers was influenced by whether or not they smoked plus the season. It was also established that the potential exposure of bus drivers to aromatic VOCs did not exceed that of an unemployed reference group, whereas the potential exposure of taxicab drivers did. Meanwhile, based on comparison of the calculated in-vehicle concentrations with those from a previous study, the VOC levels inside public buses and taxicabs were found to be lower than those inside automobiles.
Novel redox-mediator-free direct Z-scheme CaIn2S4 marigold-flower-like/TiO2 (CIS/TNP) photocataly... more Novel redox-mediator-free direct Z-scheme CaIn2S4 marigold-flower-like/TiO2 (CIS/TNP) photocatalysts with different CaIn2S4 weight percentages were synthesized using a facile wet-impregnation method. Uniform hierarchical marigold-flower-like CaIn2S4 (CIS) microspheres were synthesized using a hydrothermal method. Field-emission scanning electron microscopy and transmission electron microscopy analyses suggested that the formation and aggregation of nanoparticles, followed by the growth of petals or sheets and their subsequent self-assembly, led to the formation of the uniform hierarchical marigold-flower-like CIS structures. The photocatalytic degradation efficiency of the direct Z-scheme CIS/TNP photocatalysts was evaluated through the degradation of the pharmaceutical compounds isoniazid (ISN) and metronidazole (MTZ). The direct Z-scheme CaIn2S4 marigold-flower-like/TiO2 (1%-CIS/TNP) photocatalyst showed enhanced performance in the ISN (71.9%) and MTZ (86.5%) photocatalytic degradations as compared to composites with different CaIn2S4 contents or the individual TiO2 and CaIn2S4. A possible enhancement mechanism based on the Z-scheme formed between the CIS and TNP for the improved photocatalytic efficiency was also proposed. The recombination rate of the photoinduced charge carriers was significantly suppressed for the direct Z-scheme CIS/TNP photocatalyst, which was confirmed by photoluminescence analysis. Radical-trapping studies revealed that photogenerated holes (h+), •OH, and O2•- are the primary active species, and suggested that the enhanced photocatalytic efficiency of the 1%-CIS/TNP follows the Z-scheme mechanism for transferring the charge carriers. It was further confirmed by hydroxyl (•OH) radical determination via fluorescence techniques revealed that higher concentration of •OH radical were formed over 1%-CIS/TNP than over bare CIS and TNP. The separation of the charge carriers was further confirmed using photocurrent and electron spin resonance measurements. Kinetic and chemical oxygen demand analyses were performed to confirm the ISN and MTZ degradation. The results demonstrated that the direct Z-scheme CIS/TNP photocatalyst shows superior decomposition efficiency for the degradation of these pharmaceuticals under the given reaction conditions.
The current study evaluated the personal CO exposure of active smokers while smoking under contro... more The current study evaluated the personal CO exposure of active smokers while smoking under controlled conditions, decay rate of CO in the body following active smoking, and CO accumulation in the body from repeated active smoking using a novel device for the direct measurement of alveolar breath CO. Prior to this evaluation, the proposed alveolar CO measurement device was successfully evaluated as regards the effect of humidity, CO recovery, carryover effect, and in comparison with the bag sampling method. The breath concentrations prior to and after a single cigarette were measured using a repeated measure design. Under the controlled conditions employed in the present study, active smoking was found to cause a significant body burden of CO. The post-exposure breath CO level was 1.6-2.0 times higher than the background breath level, depending on the subject and cigarette brand. In addition, the pre- and post-exposure breath concentrations were both significantly different among the...
Although analysis of long-term data is necessary to obtain reliable information on characteristic... more Although analysis of long-term data is necessary to obtain reliable information on characteristics of atmospheric visibility and its relationship with air pollution, it has rarely been performed. Therefore, a long-term evaluation of atmospheric visibility in characteristically different Korean cities, as well as a remote island, during 2001 to 2009, was performed in this study. In general, visibility decreased in the studied areas during the 9-yr study period. In addition, all areas displayed a distinct seasonal trend, with high visibility in the cold season relative to the warm season. Weekday visibility, however, did not significantly differ from weekend visibility. Similarly, the number of days per year for both low (<10 km) and high visibility (>19 km) fluctuated during the study period. Busan (a coastal city) exhibited the highest visibility, with an overall average of 17.6 km, followed by Daegu (a basin city), Ulsan (with concentrated petrochemical industries), Ullungdo ...
AIHAJ : a journal for the science of occupational and environmental health and safety
This study evaluated worker exposure to aromatic compounds and perchloroethylene (PERC) in dry cl... more This study evaluated worker exposure to aromatic compounds and perchloroethylene (PERC) in dry cleaning stores relative to four different solvents. For benzene and toluene, there was no significant difference among the indoor air concentrations of the four different solvents. For ethylbenzene, m,p-xylene, and o-xylene, the air concentrations were significantly higher in the dry cleaning stores using Solvent V, YuClean, and Super New Cleaner than in those using a PERC mixture. Breath concentrations measured prior to and immediately after work were not significantly different for benzene and toluene, whereas breath concentrations of ethylbenzene, m,p-xylene, and o-xylene were significantly higher (p<0.05) in the samples collected immediately after work compared with those collected prior to work. The breath concentrations of benzene and toluene both prior to and immediately after work showed no upward or downward trend for 7 consecutive days excluding Sunday, starting from Monday. ...
In Korea, data for multi-route trihalomethane (THM) exposure in households using municipal tap wa... more In Korea, data for multi-route trihalomethane (THM) exposure in households using municipal tap water treated with ozone-chlorine or chlorine are unavailable or very limited. Accordingly, the present study was designed to obtain those data by measurements of the THM concentrations in the tap water and indoor and outdoor air in the two types of households, along with an estimation of THM exposure from water ingestion, showering, and the inhalation of indoor air. Chloroform was the most abundant THM in all three media, yet no bromoform was detected in any sample. Similar to previous findings, the winter chloroform concentration in tap water treated with chlorine (22.1 microg/l, median) was significantly higher than that in the tap water treated with ozone-chlorine (16.8 microg/l, median). However, the summer water chloroform concentrations and summer and winter water concentrations of the other two THMs (bromodichloromethane and dibromochloromethane) exhibited no significant difference between the chlorine and ozone-chlorine-treated water. It was suggested that the effects of the water parameters including biochemical oxygen demand of raw water entering water treatment plants should be considered when evaluating the advantage of ozone-chlorine disinfection for THM formation over chlorine disinfection. The indoor air THM concentration trend was also consistent with the water concentration trend. The indoor to outdoor air concentration ratios were comparable with previous studies. The THM exposure estimates from water ingestion, showering, and the inhalation of apartment indoor air when not in the shower suggested that, for residents living in the surveyed households, their exposure to THMs in the home was mostly associated with their household water uses. The THM exposure estimates from tap water ingestion were similar to those from showering.
This study evaluated in-car and in-bus exposures to methyl-tertiary butyl ether (MTBE), benzene, ... more This study evaluated in-car and in-bus exposures to methyl-tertiary butyl ether (MTBE), benzene, and toluene on actual commuting routes, not hypothetical routes as used in many previous in-vehicle exposure studies of volatile organic compounds (VOCs). It focuses on four potentially influencing factors (transportation mode, passenger-car type, time of day, and season). A total of 40 passenger car commuters and 20 public bus commuters were recruited. The same commuters participated in both the summer and winter studies. The transportation mode, passenger-car type and commute season were all found to affect the in-vehicle levels of the target VOCs. Conversely, the commute time of day had little effect on the in-car and in-bus levels of the target compounds. The present study also confirmed that under Korean commuting conditions, passenger car and public bus interiors are important microenvironments for exposure to MTBE, benzene and toluene. This is supported by a previous finding that both in-car and in-bus air levels of the target VOCs tend to be much higher than ambient air levels of the compounds. Meanwhile, some spurious gasoline sold during the experimental periods appears to have elevated the in-car and in-bus exposures to toluene compared with those reported by some previous studies conducted in the same study area.
The present study evaluated exposure to bioaerosols at three different types of facilities (pet s... more The present study evaluated exposure to bioaerosols at three different types of facilities (pet shops, pet clinics, and flower gardens) by measuring the bacterial, fungal and/or PM(10) concentrations in indoor and outdoor air. Regardless of the season, the total bacteria and total fungi were detected for all samples, whereas the fungal genera were not. The bioaerosol concentrations measured in the flower gardens were significantly higher than those of the pet shops and pet clinics. The mean microbial concentrations at the three types of facilities were close to or exceeded the Korean indoor bioaerosol guidelines (800 CFU m(-3)), thus suggesting the need for remedial action regarding indoor microorganisms, in order to reduce the exposure at the surveyed facilities. Another suggestion was that contrary to the airborne microbes, flower gardens are not an important microenvironment for PM(10) (particulate matter 10 microm in aerodynamic diameter) exposure. Two temporal characteristics (seasonal variation and the summer survey period) were important regarding exposure to airborne microbes, depending upon the type of facility surveyed, microbial or sample types, whereas the sampling time of the day was not. The microbial concentration ratio of indoor air to outdoor air depended upon the facility and season.
The present study evaluated exposure to two mobile source-related pollutants (CO and PM10) in hig... more The present study evaluated exposure to two mobile source-related pollutants (CO and PM10) in high-rise apartment buildings, according to floor height. The outdoor air concentrations of CO and PM10 were higher for the lower-floor apartments than for the higher-floor apartments, and they were significantly higher in the winter and summer. However, the difference of indoor concentrations between the lower-floor and
Information on the work-time exposure of public bus and taxicab drivers to volatile organic compo... more Information on the work-time exposure of public bus and taxicab drivers to volatile organic compounds (VOCs) may be a critical factor in exploring the association between occupational exposure and health effects. Accordingly, this study evaluated the work-time VOC exposure of public bus and taxicab drivers by measurement of six selected aromatic VOC concentrations in the personal air of public
bus and taxicab drivers during winter and summer. Two groups of Ave public bus drivers (smokers and nonsmokers) and two groups of Ave taxicab drivers (smokers and nonsmokers) were recruited for the study. The taxicab drivers were found to be exposed to higher aromatic compound levels than the bus drivers during their daily work time. The personal exposure of the bus and taxicab drivers was influenced by whether or not they smoked plus the season. It was also established that the potential exposure of bus drivers to aromatic VOCs did not exceed that of an unemployed reference group, whereas the potential exposure of taxicab drivers did. Meanwhile, based on comparison of the calculated in-vehicle concentrations with those from a previous study, the VOC levels inside public buses and taxicabs were found to be lower than those inside automobiles.
Novel redox-mediator-free direct Z-scheme CaIn2S4 marigold-flower-like/TiO2 (CIS/TNP) photocataly... more Novel redox-mediator-free direct Z-scheme CaIn2S4 marigold-flower-like/TiO2 (CIS/TNP) photocatalysts with different CaIn2S4 weight percentages were synthesized using a facile wet-impregnation method. Uniform hierarchical marigold-flower-like CaIn2S4 (CIS) microspheres were synthesized using a hydrothermal method. Field-emission scanning electron microscopy and transmission electron microscopy analyses suggested that the formation and aggregation of nanoparticles, followed by the growth of petals or sheets and their subsequent self-assembly, led to the formation of the uniform hierarchical marigold-flower-like CIS structures. The photocatalytic degradation efficiency of the direct Z-scheme CIS/TNP photocatalysts was evaluated through the degradation of the pharmaceutical compounds isoniazid (ISN) and metronidazole (MTZ). The direct Z-scheme CaIn2S4 marigold-flower-like/TiO2 (1%-CIS/TNP) photocatalyst showed enhanced performance in the ISN (71.9%) and MTZ (86.5%) photocatalytic degradations as compared to composites with different CaIn2S4 contents or the individual TiO2 and CaIn2S4. A possible enhancement mechanism based on the Z-scheme formed between the CIS and TNP for the improved photocatalytic efficiency was also proposed. The recombination rate of the photoinduced charge carriers was significantly suppressed for the direct Z-scheme CIS/TNP photocatalyst, which was confirmed by photoluminescence analysis. Radical-trapping studies revealed that photogenerated holes (h+), •OH, and O2•- are the primary active species, and suggested that the enhanced photocatalytic efficiency of the 1%-CIS/TNP follows the Z-scheme mechanism for transferring the charge carriers. It was further confirmed by hydroxyl (•OH) radical determination via fluorescence techniques revealed that higher concentration of •OH radical were formed over 1%-CIS/TNP than over bare CIS and TNP. The separation of the charge carriers was further confirmed using photocurrent and electron spin resonance measurements. Kinetic and chemical oxygen demand analyses were performed to confirm the ISN and MTZ degradation. The results demonstrated that the direct Z-scheme CIS/TNP photocatalyst shows superior decomposition efficiency for the degradation of these pharmaceuticals under the given reaction conditions.
The current study evaluated the personal CO exposure of active smokers while smoking under contro... more The current study evaluated the personal CO exposure of active smokers while smoking under controlled conditions, decay rate of CO in the body following active smoking, and CO accumulation in the body from repeated active smoking using a novel device for the direct measurement of alveolar breath CO. Prior to this evaluation, the proposed alveolar CO measurement device was successfully evaluated as regards the effect of humidity, CO recovery, carryover effect, and in comparison with the bag sampling method. The breath concentrations prior to and after a single cigarette were measured using a repeated measure design. Under the controlled conditions employed in the present study, active smoking was found to cause a significant body burden of CO. The post-exposure breath CO level was 1.6-2.0 times higher than the background breath level, depending on the subject and cigarette brand. In addition, the pre- and post-exposure breath concentrations were both significantly different among the...
Although analysis of long-term data is necessary to obtain reliable information on characteristic... more Although analysis of long-term data is necessary to obtain reliable information on characteristics of atmospheric visibility and its relationship with air pollution, it has rarely been performed. Therefore, a long-term evaluation of atmospheric visibility in characteristically different Korean cities, as well as a remote island, during 2001 to 2009, was performed in this study. In general, visibility decreased in the studied areas during the 9-yr study period. In addition, all areas displayed a distinct seasonal trend, with high visibility in the cold season relative to the warm season. Weekday visibility, however, did not significantly differ from weekend visibility. Similarly, the number of days per year for both low (<10 km) and high visibility (>19 km) fluctuated during the study period. Busan (a coastal city) exhibited the highest visibility, with an overall average of 17.6 km, followed by Daegu (a basin city), Ulsan (with concentrated petrochemical industries), Ullungdo ...
AIHAJ : a journal for the science of occupational and environmental health and safety
This study evaluated worker exposure to aromatic compounds and perchloroethylene (PERC) in dry cl... more This study evaluated worker exposure to aromatic compounds and perchloroethylene (PERC) in dry cleaning stores relative to four different solvents. For benzene and toluene, there was no significant difference among the indoor air concentrations of the four different solvents. For ethylbenzene, m,p-xylene, and o-xylene, the air concentrations were significantly higher in the dry cleaning stores using Solvent V, YuClean, and Super New Cleaner than in those using a PERC mixture. Breath concentrations measured prior to and immediately after work were not significantly different for benzene and toluene, whereas breath concentrations of ethylbenzene, m,p-xylene, and o-xylene were significantly higher (p<0.05) in the samples collected immediately after work compared with those collected prior to work. The breath concentrations of benzene and toluene both prior to and immediately after work showed no upward or downward trend for 7 consecutive days excluding Sunday, starting from Monday. ...
In Korea, data for multi-route trihalomethane (THM) exposure in households using municipal tap wa... more In Korea, data for multi-route trihalomethane (THM) exposure in households using municipal tap water treated with ozone-chlorine or chlorine are unavailable or very limited. Accordingly, the present study was designed to obtain those data by measurements of the THM concentrations in the tap water and indoor and outdoor air in the two types of households, along with an estimation of THM exposure from water ingestion, showering, and the inhalation of indoor air. Chloroform was the most abundant THM in all three media, yet no bromoform was detected in any sample. Similar to previous findings, the winter chloroform concentration in tap water treated with chlorine (22.1 microg/l, median) was significantly higher than that in the tap water treated with ozone-chlorine (16.8 microg/l, median). However, the summer water chloroform concentrations and summer and winter water concentrations of the other two THMs (bromodichloromethane and dibromochloromethane) exhibited no significant difference between the chlorine and ozone-chlorine-treated water. It was suggested that the effects of the water parameters including biochemical oxygen demand of raw water entering water treatment plants should be considered when evaluating the advantage of ozone-chlorine disinfection for THM formation over chlorine disinfection. The indoor air THM concentration trend was also consistent with the water concentration trend. The indoor to outdoor air concentration ratios were comparable with previous studies. The THM exposure estimates from water ingestion, showering, and the inhalation of apartment indoor air when not in the shower suggested that, for residents living in the surveyed households, their exposure to THMs in the home was mostly associated with their household water uses. The THM exposure estimates from tap water ingestion were similar to those from showering.
This study evaluated in-car and in-bus exposures to methyl-tertiary butyl ether (MTBE), benzene, ... more This study evaluated in-car and in-bus exposures to methyl-tertiary butyl ether (MTBE), benzene, and toluene on actual commuting routes, not hypothetical routes as used in many previous in-vehicle exposure studies of volatile organic compounds (VOCs). It focuses on four potentially influencing factors (transportation mode, passenger-car type, time of day, and season). A total of 40 passenger car commuters and 20 public bus commuters were recruited. The same commuters participated in both the summer and winter studies. The transportation mode, passenger-car type and commute season were all found to affect the in-vehicle levels of the target VOCs. Conversely, the commute time of day had little effect on the in-car and in-bus levels of the target compounds. The present study also confirmed that under Korean commuting conditions, passenger car and public bus interiors are important microenvironments for exposure to MTBE, benzene and toluene. This is supported by a previous finding that both in-car and in-bus air levels of the target VOCs tend to be much higher than ambient air levels of the compounds. Meanwhile, some spurious gasoline sold during the experimental periods appears to have elevated the in-car and in-bus exposures to toluene compared with those reported by some previous studies conducted in the same study area.
The present study evaluated exposure to bioaerosols at three different types of facilities (pet s... more The present study evaluated exposure to bioaerosols at three different types of facilities (pet shops, pet clinics, and flower gardens) by measuring the bacterial, fungal and/or PM(10) concentrations in indoor and outdoor air. Regardless of the season, the total bacteria and total fungi were detected for all samples, whereas the fungal genera were not. The bioaerosol concentrations measured in the flower gardens were significantly higher than those of the pet shops and pet clinics. The mean microbial concentrations at the three types of facilities were close to or exceeded the Korean indoor bioaerosol guidelines (800 CFU m(-3)), thus suggesting the need for remedial action regarding indoor microorganisms, in order to reduce the exposure at the surveyed facilities. Another suggestion was that contrary to the airborne microbes, flower gardens are not an important microenvironment for PM(10) (particulate matter 10 microm in aerodynamic diameter) exposure. Two temporal characteristics (seasonal variation and the summer survey period) were important regarding exposure to airborne microbes, depending upon the type of facility surveyed, microbial or sample types, whereas the sampling time of the day was not. The microbial concentration ratio of indoor air to outdoor air depended upon the facility and season.
The present study evaluated exposure to two mobile source-related pollutants (CO and PM10) in hig... more The present study evaluated exposure to two mobile source-related pollutants (CO and PM10) in high-rise apartment buildings, according to floor height. The outdoor air concentrations of CO and PM10 were higher for the lower-floor apartments than for the higher-floor apartments, and they were significantly higher in the winter and summer. However, the difference of indoor concentrations between the lower-floor and
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bus and taxicab drivers during winter and summer. Two groups of Ave public bus drivers (smokers and nonsmokers) and two groups of Ave taxicab drivers (smokers and nonsmokers) were recruited for the study. The taxicab drivers were found to be exposed to higher aromatic compound levels than the bus drivers during their daily work time. The personal exposure of the bus and taxicab drivers was influenced by whether or not they smoked plus the season. It was also established that the potential exposure of bus drivers to aromatic VOCs did not exceed that of an unemployed reference group, whereas the potential exposure of taxicab drivers did. Meanwhile, based on comparison of the calculated in-vehicle concentrations with those from a previous study, the VOC levels inside public buses and taxicabs were found to be lower than those inside automobiles.
bus and taxicab drivers during winter and summer. Two groups of Ave public bus drivers (smokers and nonsmokers) and two groups of Ave taxicab drivers (smokers and nonsmokers) were recruited for the study. The taxicab drivers were found to be exposed to higher aromatic compound levels than the bus drivers during their daily work time. The personal exposure of the bus and taxicab drivers was influenced by whether or not they smoked plus the season. It was also established that the potential exposure of bus drivers to aromatic VOCs did not exceed that of an unemployed reference group, whereas the potential exposure of taxicab drivers did. Meanwhile, based on comparison of the calculated in-vehicle concentrations with those from a previous study, the VOC levels inside public buses and taxicabs were found to be lower than those inside automobiles.