The ultra-fine particles emitted by automobile are emerging issue because it is known to have adverse human health effect. Particles emitted from automobile and other engines are a complex mixture of elementary and organic carbons and other chemicals. Especially diesel particles are mainly composed of elemental carbon (soot) and volatile compounds derived from unburned and partially burned fuel, and lubricating oil and sulfate. More than 90% of particle number is usually in the ultra-fine particle size range. Ultra-fine particles are known to have increased ability to cause pulmonary inflammation. Adverse health effect may be explained by the greater surface area of the ultra-fine material, which delivered oxidative stress because of a greater surface for the generation of free radicals by as yet unknown mechanisms, or for release of redox-active transition metals and organics. In conclusion, over the past decade attention has been paid on physical/chemical characteristic, mechanism, toxicity, health effects, however, we do not have enough information about ultra-fine particles. So we need to conduct continuous research and management on ultra-fine particles.

This study was carried out to investigate the presence of L. pneumophila in indoor air and water collected from 692 air conditioning cooling towers at different public facilities. For these 4 years (2001～2004) of investigation, water samples were collected in high air conditioner operating month (from July to September) at department stores, hotels, offices, hospitals, discount stores, and public agencies. It was found that L. pneumophila was present in water samples from 47 air conditioning cooling towers. The detection rate of L. pneumophila was 7.6% in 2001, 10.7% in 2002, and 9.5% in 2003, respectively. When we compared the 4 air conditioner operating months, the highest rate of L. pneumophila detection was obtained in the water samples of July. The detection rate of L. pneumophila differed among different facilities. The highest detection rate of 17.9% was found in samples from department stores. L. pneumophila was detected similarly in water samples from hospitals (8.3%) and offices (8.2%). pH, temperature, and turbidity in the 47 L. pneumophila positive water samples ranged from pH 7 to 9, from 25℃ to 38℃, and from 1.0 to 3.5, respectively.

The objective of this study was to identify the primary source of radon in Seoul subway stations, and to investigate a relationship between geology and radon. Especially, we expected that the granite areas would have substantially high levels of radon in subway stations. The indoor radon concentrations in subway stations were lognormally distributed. The geometric mean and geometric standard deviation of indoor radon concentration were 48.11 Bq/㎥ and 2.15, respectively. Indoor radon concentrations of eight measuring sites exceeded U.S. EPA criteria (148 Bq/㎥). The geological structure of the subway station regions under this study is characterized by biotite granite, alluvium, banded biotite gneiss and diluvium. Results indicate that bedrock geology can account for a significant portion of the indoor radon in subway stations. Indoor radon concentrations of one subway station were higher than those of other stations. The bed rock in this particular subway station was that of alluvium. We assumed that the unusual increase in measured radon concentration should be related mainly to the existence of the near inferred fault zone (p<0.0001). We selected ten subway stations with homogeneous bedrock type in order to compare radon concentrations of each basement level. There was a significant difference in radon concentration, depending on the basement levels in subway stations (p<0.05).

Thermal response of Korean college students was investigated in a thermal environmental chamber during summer season. Eight thermal conditions combined with four air temperatures (24, 26, 28, 30℃) and three relative humidities (40, 60, 80%) were selected. Subjects of seven females and seven males were questioned in the chamber for three hours, where thermal and comfort sensations were surveyed every fifteen minutes. During the period of thermal response experiment, four thermal parameters of air temperature, relative humidity, air velocity, and globe temperature were monitored in the test chamber. The repeatability and temporal variation of thermal response were discussed. The thermal sensation vote (TSV) of females is in good agreement with the predicted mean vote (PMV) calculated from the thermal parameters and human parameters. However, the TSV of male shows a slight discrepancy with the PMV. The neutral points of both female and male are very close to 0.18 of PMV, indicating that college-age Korean like to a slight warm environment compared with Western people. The thermal sensation vote of subjects is well correlated with the comfort sensation vote.

We have invented mobile HEPA filter unit of hemopoietic stem cell transplantation clean room (class 100), which is a capsule type to protect the patient from being infected by harmful Aspergillus spore. This equipment is based on the basic structure of US Federal Standard 209D, biological clean room standard of NASA NHB 5340-2 and measurement standard of Japanese JACA No. 24-1989. Performance of HEPA filter was evaluated by dioctyl phthalate (DOP) test method, resulting in 99.97% efficiency for 0.3 ㎛ particles. HEPA filter unit used only 98 W electricity with 24 V storage cell for the patient's treatment for over three hours. When the wind speed was 0.2 to 0.3 m/sec as in bone marrow transplantation clean room, the air flow was constant laminar vertical type. When the amount of dust was measured in the hospital, the equipment maintained the grade of clean class 100 and microbe was not detected. The noise level was less than 52 dB(A). The amounts of microbe inside and outside the building were almost same. The amount was even more in cancer sick room, serious case room and X-rays room than in the general rooms. Also, elevators and stair room were found to transport dust to other areas. Even though the patient with low immunity can be protected from Aspergillus spore by a HEPA filter unit, the system preventing microbe system such as BMT clean room should be placed in rooms such as PET, CT, MRI, and radiation room so that the patients can be protected from having infected by the extremely harmful Aspergillus spore.

Activated carbon fiber (ACF) filters are widely used to remove volatile organic compounds (VOCs) in air cleaning devices. The performance of ACF filters could be enhanced combining adsorption process with photodegradation process. In this study, to investigate this enhancement effect, a duct-type reactor was made and TiO2 was i㎜obilized on a co㎜ercialized ACF filter. Benzene, toluene, and m-xylene (BTX) were chosen as target compounds. Removal experiments for BTX were done under different air velocity and upstream concentration conditions. The range of inlet concentration was 200～1,400 ppb and the air velocities were 0.4, 0.7 and 1.0 m/s. Adsorption by an ACF filter alone showed high removal efficiency of BTX, depending on the BTX species, the upstream concentration, and the air velocity. The combination of TiO2 and ACF filter significantly increased removal of benzene which was less removed than other pollutants by an ACF filter alone. It was found that the combination effect was small in removal test of toluene and m-xylene. Removal efficiency in the tested experimental conditions was decreased in order of toluene > m-xylene > benzene.