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Aims: We assessed the levels of airborne bacteria, Gram-negative bacteria (GNB), and fungi in six hospital lobbies, and investigated the environmental and hospital characteristics that affected the airborne microorganism levels. Methods: An Andersen single-stage sampler equipped with appropriate nutrition plate agar was used to collect the samples. The three types of microorganisms were repeatedly collected at a fixed location in each hospital (assumed to be representative of the entire hospital lobby) from 08:00 through 24:00, with a sampling time of less than 5 min. Temperature and relative humidity were simultaneously monitored. Results: Multiple regression analysis was used to identify the major factors affecting microorganism levels. The average levels of bacteria (7.2 × 102 CFU/m3), GNB (1.7 × 10 CFU/m3), and fungi (7.7 × 10 CFU/m3) indicated that all hospital lobbies were generally contaminated. Season was the only factor that significantly affected the levels of all microorganisms (p < 0.0001), where contamination was the highest during the summer, significantly higher than during the winter. Other significant factors varied by microorganism, as follows: airborne bacteria (number of people in the lobby, sampling time), GNB (scale of hospital), and fungi (humidity and air temperature). Conclusions: Hospital lobby air was generally contaminated with microorganisms, including bacteria, GNB, and fungi. Environmental factors that may significantly influence the airborne concentrations of these agents should be managed to minimize airborne levels.

Dose-response analysis indicated that development of humidifier disinfectant lung injury and death were associated strongly with recurrent, intense, acute exposure without sufficient recovery time between exposures, more so than long-term cumulative exposure. These findings may explain some reversible or clinically unapparent cases among coexposed family members.

This study was conducted to assess inhalation exposure to dust, endotoxin, and microorganisms (including viable bacteria, Gram-negative bacteria [GNB], and fungi) during waste collection and sorting; to identify factors affecting this exposure; and to estimate the gastrointestinal exposure to microorganisms. A total of 48 or 49 workers involved in collecting and sorting waste from households or the street were studied. Each worker carried two personal samplers in which filters were placed in the breathing zone for estimation of inhalation exposure. To assess the possibility of gastrointestinal exposure, microorganisms on the workers' faces were collected before and after work and compared with those collected from office workers. Inhalation exposure levels were categorized according to job title, waste type handled, and working conditions and were compared using analysis of variance. Multiple regression models were developed to identify those factors that substantially affected inhalation exposure. The average exposure level to total dust was 0.9 mg/m 3 (range ϭ 0.05 to 4.51 mg/m 3 ), and the average exposure to endotoxin was 1123 EU/m 3 . The average respective exposure levels to bacteria, GNB, and fungi each exceeded 10 4 colony forming units (CFU)/m 3 . The multiple regression models found several factors that significantly explained the variation in levels of inhalation exposure to endotoxin and microorganisms; namely, sex (dust, bacteria, and GNB), job title (GNB and fungi), collection day (dust, bacteria, and GNB), temperature (endotoxin and GNB), humidity (endotoxin and fungi), and region (endotoxin) were significantly associated with exposure to these agents. In addition, the workers' faces were highly contaminated with microorganisms. In conclusion, inhalation exposure to endotoxin and microorganisms was high during waste collection and sorting, which may place workers at risk of developing various health problems, including respiratory complaints.

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Aims: We assessed the levels of airborne bacteria, Gram-negative bacteria (GNB), and fungi in six hospital lobbies, and investigated the environmental and hospital characteristics that affected the airborne microorganism levels. Methods: An Andersen single-stage sampler equipped with appropriate nutrition plate agar was used to collect the samples. The three types of microorganisms were repeatedly collected at a fixed location in each hospital (assumed to be representative of the entire hospital lobby) from 08:00 through 24:00, with a sampling time of less than 5 min. Temperature and relative humidity were simultaneously monitored. Results: Multiple regression analysis was used to identify the major factors affecting microorganism levels. The average levels of bacteria (7.2 × 10 2 CFU/m 3 ), GNB (1.7 × 10 CFU/m 3 ), and fungi (7.7 × 10 CFU/m 3 ) indicated that all hospital lobbies were generally contaminated. Season was the only factor that significantly affected the levels of all microorganisms (p < 0.0001), where contamination was the highest during the summer, significantly higher than during the winter. Other significant factors varied by microorganism, as follows: airborne bacteria (number of people in the lobby, sampling time), GNB (scale of hospital), and fungi (humidity and air temperature). Conclusions: Hospital lobby air was generally contaminated with microorganisms, including bacteria, GNB, and fungi. Environmental factors that may significantly influence the airborne concentrations of these agents should be managed to minimize airborne levels.

Since around the year 2000, hundreds of people in Korea have developed humidifier disinfectant-associated lung injury (HDLI). We collected all HD exposure-related information from the field investigations into the locations in which the 1199 registered patients had used HD. Among the people who registered, 38% (1st round = 214, 2nd = 73, 3rd = 166) were confirmed as HDLI patients. Children aged under eight years old made up the highest proportion of HDLI cases (N = 279, 62%), followed by pregnant women (N = 31, 7%). One hundred thirty-three (29%) of the confirmed HDLI patients died. Fifty-seven percent of HDLI patients (N = 259) developed HDLI after <1 year of HD use. The number of HDLI patients who used only the Oxy Saksak HD brand was found to be 176 (39%), followed by the brands Cefu (N = 27, 6%) and Aekyung (N = 22, 5%). HD products containing only polyhexamethylene guanidine phosphate (PHMG-P) were the most frequently used among HDLI patients (N = 234, 52%), followed by oligo (2-(2-ethoxy)ethoxyethyl) guanidinium (PGH) (N = 27, 6%) and a mixture of chloromethylisothiazolinone (CMIT) and methylisothiazolinone (MIT) (N = 26, 6%). The average PHMG-P inhalation level estimated from the patient group classified as suffering lung injury definitely associated with HD use was 145.1 μg/m 3 (N = 91, SD = 395.1 μg/ m 3 ), higher than levels estimated from both the probable and possible HDLI patient groups. In conclusion, HD exposure-related variables, including type of HD brand and estimated inhalation HD level, were associated with the risk of HDLI. K E Y W O R D S chloromethylisothiazolinone, humidifier disinfectant, lung injury, methylisothiazolinone, oligo (2-(2-ethoxy)ethoxyethyl) guanidinium, polyhexamethylene guanidine

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