Dispersion characteristics of respiratory droplets are important in controlling transmission of airborne diseases indoors. This study investigated the spatial concentration distribution and temporal evolution of exhaled and sneezed/coughed droplets in a ventilated hospital ward. The viability function of airborne bacteria was experimentally determined and encorporated into an air infection model with calculated results to estimate exposures and infection probability to the bacteria. The diffusion, gravitational settling and deposition mechanism of particulate matter were accounted by using an Eulerian modeling approach. The simulation results indicated that the ventilation flow was found to play a significant role in aerosol transport, leading to different spatial distribution patterns in infection droplet. The smaller size of infection droplet caused higher chance of ventilation from the outlet. The possibility of the proposed exposure estimation into the dose–response model for infection risk assessment was discussed. The infection probability is broadly different from 10^-6 to 7.2% by receptor's position and location and size of infection droplet conditions.

The aim of this study was to calculate the health risks which children were exposed to trace metals through several pathways including air, floor dust, wipe and hand wipes in elementary-schools and academies. The samples were collected at children's facilities (50 elementary-schools and 46 academies) in summer (Aug ~ Sept, 2008), winter (Dec 2008 ~ Feb, 2009) and Spring (Mar ~ Apr, 2009) periods. The lifetime Excess Cancer Risks (ECRs) were estimated for carcinogen trace elements such as As, Cd, and Cr. For carcinogens, the Excess Cancer Risk (ECR) was calculated by considering the process of deciding Cancer Potency Factor (CPF) and Age Dependent Adjust Factor (ADAF) of the data of adults. Hazard Quotients (HQs) were estimated for the non-carcinogens trace metals like Cd, Cr, Hg and Pb. The average ECRs for young children were 1×10^-9~1×10^-8 (50%th percentile) level in all facilities. Non-carcinogens did not exceed 0.1 for all subjects in all facilities. For trace metals their risk based on health risk assessment was also observed to be acceptable.

The aim of this study is to analyze the distribution of particulate matters including PM_2.5 which is known for severe adverse health effect than PM₁₀ in public facilities. The total 40 public buildings are investigated in this study and they are classified into 11 sub-groups as follows : child-care centers, medical centers, libraries, museums, bus terminals, ports, airports, railway terminals, subway stations, large-scale stores, and indoor parking lots. The mean concentration of PM₁₀ was 38.6㎍/㎥ and that of PM₁₀ in all studied facilities were lower than the Ministry of Environment's control standards. The average concentration of PM_2.5 was 27.2㎍/㎥ and that of PM_2.5 in 18 facilities were exceed the guideline of WHO (24h average value : 25㎍/㎥). The subway stations had the highest indoor level of particulate matters and the waiting area in bus terminals, railway terminals, indoor parking lots had followed in order. When comparing mean value of I/O ratio of PM₁₀, the only I/O ratio of subway stations were greater than one. In the case of PM_2.5, however, the average concentrations of PM_2.5 in indoors of subway stations, bus terminals, and indoor parking lots were higher than those of PM_2.5 in outdoors. The mean concentration of PM₁₀ and PM_2.5 were gradually increased between 6 A.M and 10 A.M and after 6 P.M in most of target buildings with increasing the number of users in thest facilities.

According to a recent government study, development and distribution of functional building materials are increasing in Korea.
In this study, we evaluated reduction performance of formaldehyde and toluene by sorptive building materials using small-scale chamber(20L) test method for 7 days.
According to the results of this study, 18 building materials showed that the effects of formaldehyde reduction among the 23 building materials. And the number of the building materials with respect to its ability to reduce the concentration of toluene was relatively small.
The mean sorption rate and total amount of sorption for formaldehyde were 36.8% and 1,525.4㎍/㎡, respectively. The sorption rate and total amount of sorption for formaldehyde were in the range 1.5∼78.4% and 87.5∼3,086.0㎍/㎡, respectively.
And the mean sorption rate and total amount of sorption for toluene were 11.6% and 1,054.4㎍/㎡, respectively. The sorption rate and total amount of sorption of toluene were in the range 0.1∼62.4% and 29.6∼6,764.0㎍/㎡, respectively.
In most cases, the performance of the building materials with respect to its ability to reduce the concentration of pollutants has steadily decreased within 7 days.

This study was performed in the 48 selected public facilities in three metropolitan cities (Seoul, Daejeon, and Kwangjoo) and three general cities (Suncheon, Gwangyang, and Yeosu) to measure of the characteristics from May to October 2011. Air samples (PM2.5) were collected at the indoor and outdoor places for 24-hrs using the mini volume air sampler and analyzed 24 gaseous and particulate polycyclic aromatic hydrocarbons (PAHs) through the GC/MS. The recoveries of gaseous and particulate PAHs ranged between 60.7% to 127.2% and 57.7% to 132.5% respectively and its relative standard deviation (RSD) was 11.1%. This QA/QC results about the were adequate for the Korean national standards. The concentration levels of the PAHs in present study were acenaphthene 〉dibenz(a,h)anthracene 〉benzo(g,h,i)perylene 〉3-methylcholanthrene 〉 indeno[1,2,3-cd]pyrene for the particulate PAHs in the 48 selected public facilities. In the case of acenaphthene, the mean concentration showed the highest levels of 22.42 ng/㎥ and 34.57 ng/㎥ in the level of gaseous and particulate phase, respectively. The total PAHs concentration for the PC room is the highest in surveyed public facilities of this study and the smoking/non smoking ratio in the PC room was 3.45. This results indicated that smoking in the PC room is seemed to play a major source and the effective risk management strategies were needed to minimize or eliminate the public health effect for customers in the PC room.

Recently, media coverages of the asbestos were gradually increased. In fact, serious problems have been found in asbestos removal. This study was performed against 375 workers from 30 asbestos removal firms from August 7 to December 10, 2010 in order to find out work conditions for asbestos removal. Then, the following results were obtained:
In terms of area, Seoul/Gyeonggi was the highest with 218 workers (58.1%). In terms of age, '41-50' was the highest among 140 workers (37.3%). The mean age was 50.3. When asked if they smoke cigarette, 272 respondents (72.5%) said 'YES.' When asked how many cigarettes they smoke a day, 11-20 (190 workers, 73.2%) was the highest, followed by 10 or less (43, 15.8%) and 'a pack or more (30, 11.0%).' In terms of average off-days per year, '1 month or less (257 workers, 68.5%)' was the highest, followed by '1-3 month(s) (77 workers, 20.5%)' and '3 months or more (41 workers, 10.9%).' In terms of annual income, 'KRW 10-20 million' was the highest with 162 workers (43.2%). No one was able to earn more than KRW 50 million. In terms of the workers' knowledge of the danger of asbestos, when asked if they were aware that asbestos can cause lung cancer, 348 respondents (92.8%) answered 'YES' while 7 workers (1.9%) said 'I am Not Sure.' According to multi-response analysis on protective clothing and gear, 369 respondents (98.9%) put on 'dust respirator' while 364 workers (97.6%) wore 'helmet.' In addition, 220 respondents (59.0%) answered that they wore 'protective clothing.' When asked how the protective clothing and gear were handled after use, 'seal them up in a designated bag and have them disposed of properly' was the response that has the highest percentage (360 respondents, 96.0%). The questionnaire consisted of 13 questions. Cronbach's alpha, which was performed to assess the reliability of the survey, was 0.858.

Particle collection efficiency and air cleaning capacity were tested for the two-stage electrostatic precipitator for use in indoor air cleaning systems. A wire-plate type ionizer was used as a particle charger and a dielectric film consisted of polypropylene (or polyethylene) coated metals and zigzagged metal electrodes was used as a particle collector in the electrostatic precipitator. Both particle collection efficiency and air cleaning capacity increased as increasing the applied voltage on the charger and the collector, and furthermore, as increasing the collector film width (i.e. collection area). Air cleaning capacities estimated by the product of particle collection efficiency and air flow rate were quite well consistent with the experimental ones with a proportional constant of 0.964. Ozone concentrations emitted from the charger at the applied voltages of 5.0 and 5.2 kV were less than 0.05 ppm, indoor ozone standards of UL 867-2002, KS C 9314 and SPS-KACA002-132. For the air flow rate of 11.7 m³/min, the applied floor area of 48.2 m² could be obtained when 5.2 kV and 6.0 kV were applied on the ionizer and the collector, respectively and the collector of two 15 mm polyethylene dielectric films was used.

This study was performed to investigate the asbestos contents on bulk samples of 4 building types(public, commercial, residential, school) in chungbuk area and collected from june 3, 2010 to July 10, 2011. We classified the bulk samples into the regulated asbestos containing building materials(ACBM) and architecture materials by 4 building types at removal and disposal sites. The results were as follows. </br>The detection rate of the ACBMs were found mainly public(86.6%), and residential (82.1%) buildings. The founded asbestos were chrysotile and amosite. Compared with 4 building types, the contents of chrysotile in public, commercial, residential and school were 32.6% (3-70%), 43.9% (5-87%), 39.6(5-72%) and 46.7%(range 4-89%), respectively. The miscellaneous materials were found chrysotile and a mixed form with chrysotile and amosite for 4 building types. </br>In the architecture materials, the contents of chrysotile was found mainly in slate (11.4%, range 2-37%). The slate in residential had high asbestos content of chrysotile (15.9%, range 1-31%). The textiles which collected from 4 building types were found chrysotile, the mixed form. The contents of chrysotile in cement flat board in public, commercial, residential and school were 8.9% (2-24%), 7.1% (1-16%), 7.9%(1-29%) and 3.7%(1-9%), respectively. </br>In conclusion, this study is suggested that it should be contributed to manage the ACBM in 4 building types and to protect the health of workers at building removal sites.