Recent research has revealed that human exposure to air pollutants such as CO, NO_x, and particulates can lead to respiratory diseases, especially among school-age children. Towards understanding such health impacts, ...Recent research has revealed that human exposure to air pollutants such as CO, NO_x, and particulates can lead to respiratory diseases, especially among school-age children. Towards understanding such health impacts, this work estimates local-scale vehicular emissions and concentrations near a highway traffic network, where a school zone is located in. In the case study, VISSIM traffic micro-simulation is used to estimate the source of vehicular emissions at each roadway segment. The local-scale emission sources are then used as inputs to the California line source dispersion model(CALINE4) to estimate concentrations across the study area. To justify the local-scale emissions modeling approach, the simulation experiment is conducted under various traffic conditions. Different meteorological conditions are considered for emission dispersion. The work reveals that emission concentrations are usually higher at locations closer to the congested segments, freeway ramps and major arterial intersections. Compared to the macroscopic estimation(i.e. using network-average emission factors), the results show significantly different emission patterns when the local-scale emission modeling approach is used. In particular, it is found that the macroscopic approach over-estimates emission concentrations at freeways and under-estimations are observed at arterials and local streets. The results of the study can be used to compare to the US environmental protection agency(EPA) standards or any other air quality standard to further identify health risk in a fine-grained manner.展开更多
In China, the technical information currently available both domestically and abroad has been reviewed in an attempt to integrate the technique of ultraviolet air disinfection with Grade Ⅱ filters and develop a steri...In China, the technical information currently available both domestically and abroad has been reviewed in an attempt to integrate the technique of ultraviolet air disinfection with Grade Ⅱ filters and develop a sterile conservation-oriented environment. As detection showed, such a sanitary system of air disinfection, integrated by ultraviolet air disinfection and Grade Ⅱ filters can reach the same standard of cleanliness as a high efficiency particle filter. This system easily satisfies the cleaning of air in hospital wards, surpassing the sterile air standards and the requirements of the National Bacteria Indicator （NBI）. As a result of this system＇s efficiency, resources and running costs can be reduced dramatically. Therefore, revision of the national standards of Structural Technical Specification of the Cleaning Operation Department needs to move forward.展开更多
文摘Recent research has revealed that human exposure to air pollutants such as CO, NO_x, and particulates can lead to respiratory diseases, especially among school-age children. Towards understanding such health impacts, this work estimates local-scale vehicular emissions and concentrations near a highway traffic network, where a school zone is located in. In the case study, VISSIM traffic micro-simulation is used to estimate the source of vehicular emissions at each roadway segment. The local-scale emission sources are then used as inputs to the California line source dispersion model(CALINE4) to estimate concentrations across the study area. To justify the local-scale emissions modeling approach, the simulation experiment is conducted under various traffic conditions. Different meteorological conditions are considered for emission dispersion. The work reveals that emission concentrations are usually higher at locations closer to the congested segments, freeway ramps and major arterial intersections. Compared to the macroscopic estimation(i.e. using network-average emission factors), the results show significantly different emission patterns when the local-scale emission modeling approach is used. In particular, it is found that the macroscopic approach over-estimates emission concentrations at freeways and under-estimations are observed at arterials and local streets. The results of the study can be used to compare to the US environmental protection agency(EPA) standards or any other air quality standard to further identify health risk in a fine-grained manner.
文摘In China, the technical information currently available both domestically and abroad has been reviewed in an attempt to integrate the technique of ultraviolet air disinfection with Grade Ⅱ filters and develop a sterile conservation-oriented environment. As detection showed, such a sanitary system of air disinfection, integrated by ultraviolet air disinfection and Grade Ⅱ filters can reach the same standard of cleanliness as a high efficiency particle filter. This system easily satisfies the cleaning of air in hospital wards, surpassing the sterile air standards and the requirements of the National Bacteria Indicator （NBI）. As a result of this system＇s efficiency, resources and running costs can be reduced dramatically. Therefore, revision of the national standards of Structural Technical Specification of the Cleaning Operation Department needs to move forward.
