OBJECTIVETo study the effect of dust exposure and smoking on mortality.

METHODSBased on the Guangzhou Occupational Health Surveillance Record System established in 1989-1992, 61,648 factory workers, aged > or = 30, occupationally exposed to dust and non-exposure to dust or any other hazardous substances(controls), were included in a prospective cohort study.

RESULTS(1) 28 were lost to follow-up. Malignant neoplasm was most common among 1,186 deaths. (2) Most subjects were male workers, aged 35 to 44, with secondary education, and married. 42.2% had ever smoked and 32.8% were ever-drinkers. (3) To compare with non-exposure, non-smoking + non-smoking and non-exposure respectively, the adjusted RR of death from all causes, malignant neoplasm and respiratory diseases were 1.24, 1.34 and 1.96 respectively for dust exposed workers(compared to control, P < 0.01), 1.16, 1.37 and 1.63 respectively for those smoking(compared to non-smoker except RR of death from respiratory diseases, P < 0.01), and 1.48, 1.85 and 3.12 respectively for those smoking and dust exposure, which were far greater than those either smoked or exposed to dust alone(P < 0.01). (4) The influence of dust exposure on death was mainly showed in occupational exposure to silica dust and wood dust.

CONCLUSIONBoth dust exposure and smoking may increase the mortality, and they had synergistic effect.

Adult ; Cohort Studies ; Dust ; Female ; Humans ; Male ; Occupational Exposure ; adverse effects ; Prospective Studies ; Silicon Dioxide ; Smoking ; mortality ; Wood

OBJECTIVETo compare the effects of dust exposure and smoking on mortality of respiratory system diseases (RSD).

METHODSBased on the Guangzhou Occupational Health Surveillance Record System established between 1989 and 1992, 80,987 factory workers, aged 30 years old or older, occupationally exposed or not exposed to dusts, were included in a prospective cohort study.

RESULTS(1) The mean age of the cohort was 43.5. Most subjects were workers, had secondary education, and almost all were married. The dust exposure rate was 16.3%, the smoking rate 43.7% and the alcohol-drinking rate 33.5%. (2) The cohort was followed up for 8 years on average, but 35 people (0.04%) were lost for follow up. Among the 1593 deaths, 219 and 90 people died of lung cancer and non-cancer respiratory system diseases (NCRSD) respectively. (3) The adjusted relative risk (RR) of death of lung cancer for smokers, 3.32, was 2.2 times of that for dust exposed workers, 1.53, and the RR of death of NCRSD for dust exposed workers, 2.41, 1.28 times of that for smokers, 1.89, especially for silica dust-exposed workers, 5.72, 3.03 times of that for smokers. Dust exposure combined with smoking caused significantly higher RR of death of RSD. (4) In male, the death risks of RSD were increased with the amount of smoking per day and years of smoking.

CONCLUSIONOccupational dust exposure and smoking may cause excessive lung cancer and NCRSD death with synergistic effects. Smoking has higher RR of Lung cancer death than dust exposure. However, the dust exposure contributes to higher RR of NCRSD death. There is a significant dose-effect relationship between smoking and the death risk of RSD.

Adult ; China ; epidemiology ; Cohort Studies ; Dust ; Female ; Humans ; Male ; Middle Aged ; Occupational Exposure ; adverse effects ; Prospective Studies ; Respiratory Tract Diseases ; etiology ; mortality ; Risk Assessment ; Risk Factors ; Smoking ; adverse effects

BACKGROUNDThe environmental sources associated with community-acquired or nosocomial legionellosis were not always detectable in the mainland of China and Hong Kong, China. The objective of this study was to illustrate the control measures implemented for nosocomial and community outbreaks of legionellosis, and to understand the environmental distribution of legionella in the water system in Hong Kong, China.

METHODSWe investigated the environmental sources of two cases of legionellosis acquired in the hospital and the community by extensive outbreak investigation and sampling of the potable water system using culture and genetic testing at the respective premises.

RESULTSThe diagnosis of nosocomial legionellosis was suspected in a patient presenting with nosocomial pneumonia not responsive to multiple beta-lactam antibiotics with subsequent confirmation by Legionella pneumophila serogroup 1 antigenuria. High counts of Legionella pneumophila were detected in the potable water supply of the 70-year-old hospital building. Another patient on continuous ambulatory peritoneal dialysis presenting with acute community-acquired pneumonia and severe diarrhoea was positive for Legionella pneumophila serogroup 1 by polymerase chain reaction (PCR) testing on both sputum and nasopharyngeal aspirate despite negative antigenuria. Paradoxically the source of the second case was traced to the water system of a newly commissioned office building complex. No further cases were detected after shock hyperchlorination with or without superheating of the water systems. Subsequent legionella counts were drastically reduced. Point-of-care infection control by off-boiled or sterile water for mouth care and installation of water filter for showers in the hospital wards for immunocompromised patients was instituted. Territory wide investigation of the community potable water supply showed that 22.1% of the household water supply was positive at a mean legionella count of 108.56 CFU/ml (range 0.10 to 639.30 CFU/ml).

CONCLUSIONSPotable water systems are open systems which are inevitably colonized by bacterial biofilms containing Legionella species. High bacterial counts related to human cases may occur with stagnation of flow in both old or newly commissioned buildings. Vigilance against legionellosis is important in healthcare settings with dense population of highly susceptible hosts.

Aged ; Aged, 80 and over ; Biofilms ; Community-Acquired Infections ; diagnosis ; epidemiology ; Female ; Hong Kong ; epidemiology ; Humans ; Legionellosis ; diagnosis ; epidemiology ; Male ; Water Microbiology