This paper describes the current status of continuous ventilation system mandatory in houses according to the building standard law as a countermeasure of sick house syndrome enforced 5 years ago. Background situation of the specified amount of ventilation requirement, characteristics of formaldehyde as a contamination source and appropriate measurement technique of net air volume of total heat exchanger unit are discussed. The performance requirements for continuous ventilation system of highly airtight houses are discussed.
The law for maintenance of sanitation in buildings establishes the building sanitation management standards and the methods for monitoring indoor environments in buildings. Suspended particles, one of the monitoring items in the law, are measured by the gravimetric method with a low-volume air sampler or equivalent methods with calibrated equipment, such as a dust meter. Dust meters have been commonly used to monitor indoor particle concentrations in buildings. Mass concentration in indoor are calculated with the data from dust meters and the coefficient of calibration, K value. This paper reports the overview about the methods of measurement for suspended particle concentration and calibration for dust meters , the K value in the law. The relationship between suspended particle concentrations in recent office buildings is discussed.
In Japan since 1996, “Bun-en (smoking area isolation) ” has been promoted as a solution for preventing passive smoking by the initiative of the Ministry of Health, Labor and Welfare in Japan. In 2002, the Ministry of Health, Labor and Welfare reported that the reduction in the concentration of particulate component generated by tobacco smoking is not sufficient for the prevention of passive smoking, and that the importance of reducing gaseous components was suggested. In addition, ventilation equipment was recommended to protect nonsmokers from passive smoking by reducing both gaseous and particulate components. The author measured the concentrations of particulate and gaseous components (carbon monoxide) generated from tobacco smoke in smoking area where the air purifier and air ventilation system were installed, and showed the effectiveness of simultaneous usage of air purifier and the air ventilating equipment for tobacco smoke.
Increase in nanoparticle due to the diesel engine exhaust and the secondary formation from atmospheric gaseous contaminants has been observed in the atmospheric environment. In indoor air, exposure to airborne particulate matters including ultrafine particles has an adverse health effects especially to respiratory tracts. There are previous works on the sources of indoor ultrafine particles, such as cooking, smoking, spraying, a scent candle burning, and laser printers. The measurement methods of particle emission rates from a copier or printer are specified in ISO standards, however it is difficult to evaluate the ultrafine particle emission rates by using this method. Since the discussion of ultrafine particle emission mechanisms is now going on, it is important to develop the emission chamber for printers, and analyze the chemical composition of emitted particles so as to clarify the particle formation mechanisms in the office equipments.
Events following Sept. 11, 2001-particularly the anthrax mail scares-heightened awareness of the threat of bioterrorism. Immediately after 9 · 11 coordinated-terrorist-attacks events, the President of the United States established by executive order the Office of Homeland Security, which is mandated “to develop and coordinate the implementation of a comprehensive national strategy to secure the United States from terrorist threats or attacks ”. At the same time, Defense Advanced Research Projects Agency (DARPA) started the Immune Building project. Various bioterrorism prevention technologies have been devised by the Immunity Building project. In the first half of this paper, the present status of the countermeasures against bioterrorism on “protecting building environments from airborne biological attacks ” are reviewed. In the second half, the authors' research findings, the real time detection of airborne microbes, the experimental results of the disinfection to the air-conditioning systems using ozone, etc., are introduced.
In designing electrostatic atomization devices which produce fine water droplets, it is very important to understand the relation between the discharge current and the behavior of the water condensate on the tip of the discharge electrode in order to clarify the generation mechanisms of the fine droplets by electrostatic atomization. In this study, the relation between the waveform of discharge current and the periodical formation and breakage of the water condensate is investigated. The discharge current is measured as a periodical pulse group, and it is confirmed that the amount of the discharge current in the first pulse mainly dertermine the density of the fine water droplets.
This paper addresses the issue of measuring the size distribution of nonspherical mineral dust particles by use of an optical particle counter (OPC) on the basis of comparison with transmission electron microscopic (TEM) analysis by a laboratory experiment and the theoretical computation of light scattering by nonspherical particles. The dust particles were monodispersed in the electrical mobility radius of 0.25 and 0.5 μm and their size distribution were measured with the OPC and TEM and compared. The volume equivalent mode radii obtained with the OPC was 0.06-0.09 μm larger than that obtained with the TEM. The size distribution width (standard deviation) obtained with the OPC was 5-13 % larger than that obtained with the TEM. Theoretical computation of the light scattering by triaxial spheroids showed the large variation in the light scattering intensity depending on the particle orientation, which can result in the large size distribution width obtained with the OPC. These results show that particle nonsphericity critically affects the measurement of dust by use of the OPC and care should be taken in utilizing the measured size distribution.
The performance of a newly developed impactor filter sampling system (IF) to classify ultrafine particles (UFP) under atmospheric pressure was evaluated by comparison with a low pressure impactor (LPI) sampler. Tests were carried out in field samplings of atmospheric aerosol. The results showed that the IF is capable of collecting UFP without altering the composition compared to LPI, and the collected amount of OC and EC is 1.4 ∼ 1.6 times higher than LPI sampler. Furthermore, the determination of ionic components like SO42-, NO3- and NH4+, indicated that highly-volatile components are volatilized more significantly when using the LPI sampler. The IF was used to sample PM2.5 and PM0.1 during summer and winter at the roadside of a busy national road. The chemical composition analysis indicated that only PM0.1 had seasonal variation on OC composition, whereas ionic components existed mainly in larger particles. Larger particles seemed to be affected by background particles at the roadside, while PM0.1 were strongly influenced by motor vehicle emissions. Moreover, the relationship between the chemical components in PM0.1 and particle number concentrations confirmed that homogeneous particle growth dominates in summertime, while heterogeneous particle growth dominates in wintertime.