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vol.51-1(2013/5/31)
| Architectural measures to avoid insect damage |
| Insect invasion into buildings cause various problems. Though, there have been no definitive treatments to avoid insect damage without use of insecticides. Architectural measures to avoid insect damage are drawing attention as a safe and effective technique. Here I describe what the architectural measures are about and how to construct. |
| Behavior of nanoparticle and the measurement technique --Unipolar charging of nanoparticles with surface plasma aerosol charger-- |
| Electric mobility classification is the most powerful way to classify and determine nanoparticle properties. However the charging efficiency for nanoparticle is extremely small so that a large fraction of nanoparticles do not migrate in an electrical field. Furthermore, even if we could charge nanoparticles at a higher charging efficiency, they are apt to easily deposit by an electrical field formed in a charger. In the present work, Microplasma-based aerosol charger was developed for high-efficiency and high-throughput charging of sub-10nm nanoparticles. The optimization of discharge voltage supplied to the surface discharge microplasma device was carried out in order to achieve high charging ratio and minimum electrostatic loss of charged particles. Among various waveform voltages tried, time-dependent voltage of (V0/ωt) sin ωt was found to yield the highest charging efficiency. By applying bias voltage opposite to the polarity of discharge electrode, it was found that more than 80% of the 10-nm aerosol particles were negatively charged (intrinsic charging efficiency : 80%) and nearly 60% of particles introdoced to the charger were recovered as negatively charged particles at the outlet of the charger (extrinsic charging efficiency : 60%) at the optimum charging conditions. The effect of particle diameter and aerosol flow rate on the charging efficiency was also evaluated. |
vol.51-2(2013/7/31)
| Structurization of Electrospun Nanofiber Layer for Aerosol Filtration |
| Recently, nanofibers are applied in various field, such as air filter, cellular medium and solar cell. However, the correlation between fiber morphology and physicochemical properties in precursor solution are still unknown. In this review, polyacrylonitrile (PAN) nanofibers with various morphological structures were produced by electrospinning by controlling the physicochemical properties (viscosity, surface tension, and electrical conductivity) in the precursor solution. Quantitative evaluation showed that fiber morphology was strongly influenced by precursor viscosity, and the viscosity thresholds affecting fiber morphology (ribbon-like, straight, spindle-like beaded, and beaded) were clarified. Using a monodisperse aerosol, the air filtration performance of filters made with these fibers was evaluated based on quality factors. Filters composed of beaded fiber showed the best quality in the air filtration test. |
| Microbial cleaning of metal ion containing solution |
| In this review, the potential of tungsten(W) recovery via biosorption using Escherichia coli was assessed to establish an environmentally friendly recycling system. The effective removal of W from industrial wastewater is among the most important issue on the environment protection due to its toxicity. In this study the potential of biosorption using E.coli for the W elimination from Na2WO4 aqueous solution was assessed at various pH, temperature, initial W and cell concentrations. As a result, the elimination fraction of W was strongly depended on pH of solution and the highest W uptake capacity was obtained at initial pH 1.0 - 2.6. The best isotherm fit for W was obtained with the Langmuir model. Furthermore, desorption of W from E.coli was completely achieved by controlling pH of solution. Finally, heating the W adsorbed microorganism yielded a solid condensate containing 97% WO3. |
| Biological contamination and odor problem from humidifier element of air conditioning unit |
| This report showed the study for finding the source of odor problems from HVAC systems in a building. The building had odor problems in the room in summer season. The humidifier elements in air conditioning units on which microorganisms might reproduce could be predicted as an odor source of this room. To investigate the emission compounds, the biological contaminants on the humidifier were identified. Then the small chamber tests for emissions from the humidifier element and biological contaminants adsorbed on the element were carried out. As a result, fusarium sp. was detected on the elements and MVOC from fusarium sp. could be identified as dimethyl disulfide. Since dimethyl disulfide was also detected from the humidifier element by the chamber method, the source of the odor in the room could be the humidifier element surface contaminated by fusarium sp. |
| Simple Valuation Method of Radioactivity on an Air Filter Caused by Fukushima Nuclear Accident |
| The simple valuation method of the radioactivity on an air filter which was pollution by the Fukushima nuclear accident is required. We measured the radiation dose rate from a filter side, calculated the conversion coefficient which presumes the radioactivity on a filter using a 1-cm dose equivalent rate constant, and performed verification by survey. The value evaluated by this method and the quantitative analysis value by germanium semiconductor detector were equal to the rough value level. Since form of an air filter is complex, this method considers that we are practical. |
| The germ-killing process by formaldehyde |
| The germ-killing process by formaldehyde has been used widely from small space such as safety cabinet to large room such as pharmaceutical factories. However, Specified chemical substance obstacle Ordinance on Prevention was revised, and formaldehyde rank rose in the second material from the third, and the use of formaldehyde is often avoided. Recently the germ-killing process by hydrogen peroxide or ozone or peracetic acid is reported. However, these substitute drugs are powerful oxidants, and has the strong corrosiveness for materials. On the other hand, formaldehyde has few corrosiveness. In addition, formaldehyde is very high effective drug that kills a spore bearing bacterium, and it is used in still now many institutions. This commentary mentions a germ-killing process, an elementary knowledge for formaldehyde drug, a legal regulation and so on and the practical side of the germ-killing process by formaldehyde. |
| Nanoparticle counting method for ultrapure water |
| This article describes particle counting method for ultrapure water which is used for semiconductor manufacturing process. It especially describes membrane filtration counting method including its basic principles, measurement procedure and measurement accuracy. As the density of large scale integrated circuits (LSI) is getting higher, demand for control of small particle in the order of magnitude of 10 nanometers is increasing. Principle of membrane filtration counting method can satisfy the requirement for the measurement of nanoparticle as specified by International Technology Roadmap for Semiconductor (ITRS). To measure the quantity of the nanoparticles contained in ultrapure water exactly, the water is filtrated by membrane filter and the particles captured on the filter surface are counted under scanning electron microscope (SEM). Therefore statistical approach is essential in estimating the total particle count of a filter based on the observed number of particles on a limited area of the filter. As it is very important to reduce the effects of the particles that are originally adhering to the filter, solutions for such problems are also described in this article. |
vol.51-3(2013/9/30)
| Ultraviolet rays sterilization--Past, present and future |
| Since ultraviolet rays were discovered by Johann Wilhelm Ritter 200 years ago, ultraviolet rays have been applied to many fields include air purification. The technology of sterilization by ultraviolet rays has been established now. In this article, after describing the characteristic of ultraviolet rays, influence on people’s health, and sterilization by ultraviolet rays, it introduces about the sterilization example of the ultraviolet rays in general environment. As the Draft Minamata Convention on Mercury to be adopted by the related country under the name of the Minamata treaty, and to be signed in Kumamoto on October 10, 2013, utilization of a new type ultraviolet-rays lamp is attained. |
| Sterilization of the air using ultraviolet rays〜Repot from the various facilities〜 |
| UR-UVGI is air sterilizers that introduction is relatively easy. We have carried out many examinations of floating bacteria in various facilities, the problem that we must work on became clear from these experiences. We must study effective combination of UR-UVGI and air-conditioning system to let UR-UVGI show a stable bacterial killing ability. |
| The application of ultraviolet radiation technology to water treatment, with related problems |
| Ultraviolet radiation (UV) consists of electromagnetic waves with a wavelength of 100-400 nm. Water purification technologies employing UV are utilized for the inactivation of microorganisms and the reduction of organic compounds in wastewater. In the former, the UV source wavelength is 253.4 nm; and in the latter, 184.9 nm (when only UV is employed) or 253.7 nm (with the addition of oxidizing agents). Such UV disinfection or sterilization technologies have recently become widespread as a replacement for chlorination disinfection techniques in secondary sewage effluent treatment, and are typically employed in the sterilization of raw materials in a host of industries, including food and drink manufacturing. In 2007, UV technology was introduced for water treatment, as a measure against chlorine-tolerant pathogenic microorganisms such as Cryptosporidium, which are only slightly inactivated by chlorination; and thus far, a total of 224 cases of such use have been recorded in Japan, including a plan initiated at the end of 2012. In addition, UV technology is used as a growth suppressor (inhibitor) for algae, particularly the blue-green algae, Microcystis, which causes serious problems in aquatic environments; and more than 300 cases of such use have thus far been reported in Japan. Moreover, UV technology is further recognized as a useful technique for the inactivation of viruses such as norovirus. In light of this, it is expected that UV technologies will become indispensable for the improvement of aquatic environments. |
| The present condition and the subject of ultraviolet-rays use in food and a medical field |
| This paper describes current situations and problems of UV sterilization. It is mainly used in the food and the medical fields. The ways to use it are divided into three groups: air sterilization, surface sterilization, and running water sterilization. Each of these is used for different targets and has a different structure. |
| Application and development to environmental purification of new UVA-LED |
| We focused on a disinfection device of UV light-emitting diode (UV-LED) whose development has rapidly advanced in recent years. UV-LED has a long life, additionally, is nothing to generate with environmental pollution of mercury waste. If UVA-LED could be used instead of a conventional low-pressure mercury lamp, miniaturization of the device and expansion of a practical use field might be recognized. At present, general-purpose model of UV-LED with the shortest wavelength that can be obtained at a commercial level is UVA-LED. We developed a new disinfection device equipped with high-energy UVA-LED. We investigated UVA-LED-induced DNA damage and compared it with UVC-induced DNA damage. At the same level of inactivation, levels of 8-OHdG, a major indicator of oxidative DNA damage, in UVA-LED-irradiated cells were 2・6-fold higher than those seen in UVC irradiated cells. On the other hand, CPD, an indicator of direct DNA damage, in UVA-LED-irradiated cells were much less than those seen in UVC-irradiated cells. We newly developed UVA irradiation system and found that UVA alone was able to disinfect the water efficiently. This will become a useful disinfection system. |
| The energy conversion factor for a pharmaceutical factory |
| The energy conversion factors (ECFs) for a semiconductor factory were formulated in 2001 and revised in 2009 by energy saving committee of JACA technical committee. They are effective to understand the energy consumption of the each utility of the manufacturing equipments, and the energy consumption in the entire factory. And the ECFs are used as a benchmark when performing energy cunservation measures, and are quoted SEMI standard S23. Similar to the semiconductor factory, a pharmaceutical factory has a clean room and equipments. And it resembles the semiconductor factory in that the air conditioning takes a large amount of fresh air and a large amount cunsumption of compressed air, pure water and so on, and cumsumes a large amount of energy. Therefore, to formulate the ECFs for pharmaceuticals becomes to contribute to the energy saving. This paper describes ECFs for pharmaceuticals are formulated in what way. |
| Evaluation of workplace environments for engineered nanomaterial production and technique of nanoparticle emission |
| Risk relevant to nanomaterial handling is determined by exposure and hazard potential of these materials. Both topics could not be evaluated precisely and independently. Realistic dose concentrations should be quantified based on accurate exposure assessments for the corresponding nanomaterial taking into account also the environmental and product complex. This article introduces on current available information from publications related to airborne nanomaterial exposure. Two approaches to obtain realistic exposure values are presented; ones based on workplace measurements and the others based on sumulations in laboratories. An assessment of the current available workplace measurement data using a matrix, which is related to nanomaterials and work processes, shows those data are available on the likelihood of release and possible exposure. Meanwhile, laboratory studies are seen as an important complementary source of information on particle release processes and hence for possible exposure. In both cases, whether workplace measurements or laboratories studies, the issue of background particles is a major problem. Furthermore, the issue which could take place when agglomerates composing nanomaterials are collected and their size are measured is pointed out in this article. |
vol.51-4(2013/11/30)
| Introduction of ozone sterilization technology |
| The ozone can sterilize a spore-forming bacteria with a strong oxidation power. Ozone concentration, humidity, sterilization time is an element of sterilization. We revealed in the basic test the ozone sterilization conditions of spore-forming bacteria and general bacteria. We calculated the D value of spore-forming bacteria from this result. High humidity is an important factor of spore sterilization, tests device were placed in a constant temperature bath. Sterilization systems and sterilization conditions in a variety of field is created based on this condition. In the field, the conditions to locate the cold spot of sterilization, can be completely sterilized in this place has been set. Before operation, sterilization confirmation test with spore indicator bacteria was repeated many times. This report is to introduce the actual know-how that were the basic test results and used in the field of the production system. |
| Room Decontamination by Vaporized Hydrogen Peroxide |
| Bio-Decontamination by the Dry Process of Vaporized Hydrogen Peroxide has broad material compatibility, and can respond to various object spaces. And it has broad kill spectrum and even low concentration shows highly sporicidal. In recent years, it is becoming the global standard currently used for large-scale room decontamination. |
| A new system for Bio-decontamination by vapor phase hydrogen peroxide |
| A new decontamination system, HYDEC, introduced here does not require humidity control, minimizes decontamination time, and reduces the mass of hydrogen peroxide used, offering another new approach to kill microorganisms using vapor phase hydrogen peroxide (VPHP). A study was conducted during the development stage, using 6.5m3 filling isolator to determine the lethality of biological indicatiors under different humidity levels. The results showed that decontamination was possible only by adjusting the injection rate of hydrogen peroxide if the humidity was within normal humidity levels in cleanroon (40-60%RH). The HYDEC system optimized for use in a 80m3 room achieved a decontamination of 4-6 LRV within 5 hours including aeration. Currently this new system is employed for decontamination of numerous isolators and cleanrooms. |
| Modern technology of Peracetic acid for space and environmental surface |
| The call for environmentally friendly disinfectants as biocides has become the benchmark in choosing an alternative for formalin replacement to be used in aseptic operation processes. Among those are; pharmaceutical industries, tissue engineering industries, food processing industries, experimental animal industries and research laboratories. US Environmental Protection Agency (EPA) has classified particular peracetic acid as a sterilant and the application has been widely used in the industries with aseptic processing facilities. Also, peracetic acid as biocide used in pharmaceutical and tissue engineering clean rooms is subject to US Food and Drug Administration (FDA) and the United States Pharmacopeia (USP) guidelines. In addition to the use of peracetic acid for surface disinfection like soaking, wiping and spraying, fogging with peracetic acid as an adjunct to regular disinfecting on hard room surfaces also draw much attention as a robust and cost effective method. In this article, we look at peracetic acid as biocide for dry fogging and what US EPA, Centers for Disease Control and Prevention (CDC), FDA and USP have to say about the latest environmental disinfection. |
| Indoor air quality control with low concentration chlorine dioxide gas |
| Chlorine dioxide gas has a potent antimicrobial activity at extremely low concentration and may serve as a new tool for infection control. Chlorine dioxide reacts with two amino acids, tyrosine and tryptophan and causes viral protein denaturation. In hemaglutinin, protein on influenza virus surface, the 153rd tryptophan in it is oxidized with chlorine dioxide and changed its molecular structures. As for floating bacteria and viruses, 0.02ppm of chlorine dioxide gas killed over 99% of them within several hours. When rats were kept in the atmosphere maintained chlorine dioxide gas concentration of 0.05 and 0.1 ppm for 6 months, chlorine dioxide gas did not show the toxicity to whole bodies of rats. When chlorine dioxide gas generating gels were set into office rooms, chlorine dioxide gas exposure decreased the rate of workers who had influenza-like illness. |
| Containment of Hazardous Particulate Material in Facilities for Highly Active Medicals --Evaluation of Containment Performance Using a Surrogate Material-- |
| This paper reports about a new evaluation technique of hazardous particulate containment performance on the assumption that highly active medicals are treated in the pharmaceutical facilities. The evaluation technique uses adenosine-triphosphate (ATP) as a surrogate material, instead of lactose, which is used conventionally for assessing the particulate containment performance of pharmaceutical equipment. The quantity of ATP is easily measured by using commercial appliance, which is using usually for detection of microbiological contamination in food manufacturing facilities. Because the quantity of ATP is in proportion to the fluorescence value read by measurement appliance, the quantity of ATP in a sample can be known. The detectivity of ATP is higher than the detectivity of the lactose, and moreover, the time for measurement of quantity of ATP is shorter than the time for that of lactose. We present the results of diffusion behavior of powder, using ATP as a surrogate material, when the powder is dropped down to the floor, when the powder is stirred on the table, and when the powder scattered on the floor is stamped on. |
| Outline of indoor air environment |
| The histories of atmospheric air pollution in Europe, U.S.A. and Japan were described including Donora smog, London smog, and Yokkaichi Asthma. After referring Japanese laws for environmental pollution control, present situation of atmospheric air pollution was described. The history of indoor air environment was also presented, representatively indoor air pollution by heating, passive smoking and sick house syndrome. Then the basic idea for keeping good indoor air quality, or controlling indoor air pollution, was presented with putting on stress of the importance of ventilation. The history of ventilation was presented. Finally, thermal comfort of indoor air environment was explained. |
vol.51-5(2014/1/31)
| Outline of Industrial Safety and Health Law of 1972 and regulations on hazardous chemicals under the Law |
| Industrial Safety and Health Law of 1972 is the central and comprehensive law in the area of occupational safety and health of Japan. The law stipulates employers’ responsibility to establish, at respective workplaces, management system of occupational safety and health and take necessary measures for prevention of industrial accidents and occupational diseases. In regard to the prevention of occupational diseases due to hazardous chemical substances, there are ordinances for specified chemical substances, organic solvents, lead and its compounds, respectively. The administration, having been influenced by risk-based approaches performed in EU countries, now puts priority on encouraging employers to take necessary measures, from their own will, regardless of whether they are required or not by laws and regulations, based on risk assessment by themselves. |
| Enforcement of the Working Environmental Measurement (for Specified Chemical Substances and Organic solvent) and the Risk assessment of Chemical Substances |
| In the indoor workshop handling a toxic substance, enforcement of the working environmental measurement is required by the place that laws and ordinances determine. I give an outline including a way of thinking of a recent trend and the risk assessment of the chemical substance about enforcement of the work environmental measurement to modify specified chemical substance and organic solvent here. |
| Local Exhaust System for Working Environment Improvement and Its Design |
| Local exhaust ventilation technique is widely applied for reducing employee exposures to airborne contaminants in workplace resulting from industrial operations. It is the prefered method of contamination control because it operates on the principle of capturing contaminants at their emmission sources for removal before they pollute the working environment. Local exhaust systems are comprised of four basic elements, i.e., the hood(s), the duct system, the air cleaning device, the fan, and the exhaust stack. Although successful plan and design of a local exhaust system considerably depend on an accumulated experience in addition to a knowledge, this paper concisely describes a basic knowledge including calculation method and figures reqiured for plannning and design of the hood and the duct system. |
| Some cases of improvement measures for work environments handling harmful chemical substances by a push-pull type ventilation system |
| Chemical substances having many useful properties are used for many purposes such as the raw materials of the products, manufacturing process and medical care site. It is estimated that about 60,000 chemical substances have been used already and approximately 1,000 is newly introduced in every year. In these chemical substances, some have a hazardous property of explosion, fire or abnormal reaction, as well as acute and chronic poisoning to human. However, many of those chemical substances have not been cleared their hazardous properties, and those cleared are only several thousands hitherto. This paper reports some cases of improvement measures for work environments handling harmful chemical substances by a push-pull type ventilation system. The work environments are printing shop and medical service, and the chemical substances handled are an organic solvent, formaldehyde, glutaraldehyde and ethylene oxide. |
| A new ventilation system for decreasing formaldehyde gas concentrations in gross anatomy laboratories |
| We designed and constructed a new ventilation system for dissecting table to decrease formaldehyde concentrations in gross anatomy laboratories, by using numerical simulation and visualization of airflows around dissecting tables. This ventilation system prevented the diffusion of formaldehyde gas from dissecting tables by covering those in the unidirectional airflow. The performance of this ventilation system was evaluated according to Industrial Safety and Health Act in Japan. As a result, we confirmed that formaldehyde concentrations in gross anatomy laboratories were much lower than the allowable value 0.1ppm provided in Industrial Safety and Health Act in Japan. |
| Improvement of Working Environment with Drifting Chemical Substances Based on Air Flow Control |
| To have workers engage in the job handling chemical substances, it is necessary to apply engineering measures to minimize the risk of chemical exposure. As the measure to improve working environment at an anatomy laboratory, which is regulated according to the Ordinance on Prevention of Hazards Due to Specified Chemical Substances, this paper introduces a dissecting table equipped with the function of local exhaust ventilation, and presents the case where blowing air flow affects the performance of this function. In addition, as the measure to improve working environment at a printing workplace, which is regulated according to the Ordinance on Prevention of Organic Solvent Poisoning, this paper introduces push-pull type ventilation systems (oblique down-flow and horizontal flow), and presents the case where both working environment and odor environment are improved through the introduction of these systems. |
| Removal Technology of Formaldehyde and Countermeasure in a General Hospital |
| The issue of formaldehyde pollution in the general residence environment was improved by guideline establishment of Ministry of Health, Labour and Welfare and revision of the Building Standard Act. On the other hand, about the workplace such as pathology laboratories, the exposure concentration of formaldehyde is still high in many cases, because there is not an effective improvement method by the existing technique. We developed a new removal technology to function in the highly-concentrated formaldehyde environment and introduced it into a pathology laboratory of general hospital. According to the actual measurement results, we cleared the management concentration (0.1ppm) by using the formaldehyde removal technology and an airflow control technology in the pathology laboratory. In addition, the formaldehyde concentration of the exhaust air is reduced to fresh air level. In other words, that was able to protect workers' health and the environment at the same time. |
| Exposure measurement of manufactured nanomaterial in the workplaces For quantitative assessment |
| For exposure assessment of nanomaterial, we can apply various types of instruments and chemical analysis. In the present paper, we show a three-step measurement procedure for work environments based on guidance documents published by different bodies. The procedure includes pre-survey of processes and materials handled in a workplace, preliminary measurement of emission sources by portable instruments, and speciation of particles with size distribution measurement, electron microscopic observation, and chemical analysis. At present, several metrics should be selected to evaluate exposure in the workplaces. |
| Air quality and health effects |
| Over the past forty years, lots of effective measures have been taken to improve air pollution. However, as a result of major changes in building materials, comsumer products of lifestyle, and scientific findings on health effects associated with air pollution, new issues have been suggested such as phthalates and phosphates in indoor dusts, indoor secondary emissions, dampness, mould, and indoor fine particulates. Continuous and integrated risk assessment and exposure monitoring for finding high risk factors would be needed. In addition, comprehensive framework for further transparent information for emission sources, ingredients of products or management indoors would be needed. |
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Air Cleaning Association