The Study of High Frequence Hearing Loss in Pilots

BACKGROUND: Hearing loss is associated with environmental noises. Not only the strength of the noise but also the exposure time of that seems important. We investigated to find the factors associated with hearing loss in pilots. METHOD: For the anlysis of hearing loss in pilots in the air force, we performed an audiometiric test on 563 pilots from 2000 to 2001 and analysed the results. REUSLT: The type of aircraft or regiment is not associated with hearing loss. The age, tenure and total flight time are the factors associated with hearing loss, especially in the high frequency zone. The flight time in the recent six months is shown not to be associated with hearing loss which means an exposure to noise in a longer term is important. In this study, the hearing threshold increased at 6,000 Hz regardless of age. CONCLUSION: The reason may be due to the noise environment of pilots. Therefore an additional study about pilots' normal limits of hearing threshold at 6,000 Hz and clinical meanings of that is necessary.

Difference of Hypoxia Tolerance with Reference to Sex

BACKGROUND: Time of useful consciousness is related with various factors including smoking, age, sex, drug, and temperature. It is still unclear whether acute hypoxia tolerance is different between male and female. METHOD: We included 32 healthy students (male, n=16; female, n=16) volunteered to participate in this study. The blood hemoglobin concentration was measured at a day before flight. With high altitude rapid decompression flight training chamber, flight to simulated altitude of 25,000 ft was performed after nitrogen extraction breath. At 25,000 ft, heart rate and arterial O2 saturation (SaO2) were measured by using pulse oximeter after taking off oxygen mask. We compared the duration from mask-off to the time at 60% SaO2 between male and female and correlated the time at 60% SaO2 with hemoglobin concentration. RESULTS: The duration from mask-off to SaO2 reaching 60% were significantly longer in the male group. There was a linear relationship between hemoglobin concentration and time at 60% SaO2. CONCLUSION: Acute hypoxia tolerance differs from the two sexes and the difference of hemoglobin concentration is one of possible causative factors of this difference.

The Study on Relaxed G-tolerance Beween Men and Women

The relaxed G-tolerances of 16 female cadets of ROKAF academy and 19 male privates were compared. The relaxed G-tolerance level was measured as visual endpoint (gray out or loss of peripheral light loss) during G-force raise steadily at 0.1 G/s. The G-stimulations were repeated twice with the interval of 30 s for 4 days (female cadets, 9 a.m.; male privates, 10 a.m.). The correlation between the relaxed G-tolerance level and their physical factor (height, sitting height, weight and lean body mass) and muscle strength (power of abdomen, back and thigh) was investigated. The average value of the relaxed G-tolerance levels of female cadets for 4 days was significantly higher than the one of male privates (4.23 +/-0.60, n=111; 4.04 +/-0.64, n=92; student 's t-test, P<0.05). However, the training effect of 4 days was not seen in either female cadet or male private group. The weight and lean body mass have significant positive correlation with the relaxed G-tolerance level. Also, the peak torque of thigh muscle have a strong positive correlation with it, but the endurance ratio does not.

Health Effects of Air Particle Produced in a Waste Treatment Plant on Residents Living in an Official Residence of Air Base

BACKGROUND: This study was conducted to reveal the health effects of air pollution on the residents living near waste treatment plant. METHODS: We sampled 190 residents as the hogh exposed group, 192 residents as the moderate group, and 139 residents as the low exposed group according to the geographical distances from the waste treatment plant. Self-administered questionnaires for prevalence of respiratory disease, irritation symptoms of mucous membrane (eye, nose, thoat, skin, and respiratory tract), gastrointestinal symptoms, other nonspecific symptoms were conducted. We measured the concentrations of total suspened partcles, Zn, Cu, Cr, Ni, Pb, Cd and As in 3 exposed area. RESULT: Airborne concentrations of total suspended particles measured in exposed area were 485, 365, and 332 micro gram/m(3) which excees the limit value. Airborne concentrations of Zn, Cu, Cr, Ni, Pb, Cd and As were not excees the limit value. The prevalence of respiratory disease of high exposed group (16.8%) was significantly higher than that of moderate group (3.6%) and low exposed group (5.0%). The sysptom score of irrtation sysptoms of mucous membrane, gastrointestinal sysptoms, and other nonspecific sysptoms were increased with exposed level. In multiple linear regression, exposure level was related to all sysptom scores significantly. CONCLUSION: These results suggest that the air pollution of waste treatment plant would influence prevalence of respiratory disease, induce irritation of mucous membrane, gastrointestinal symptoms, and other nonspecific sysptoms.

A Study on Worker Exposure to Methylene Chloride in Aircraft Paint Stripping Operation

BACKGROUND: Workers who are related with paint stripping process of aircraft parts can be exposed methylene chloride, phenol, chromium hexavalent in using paint remover. Especially, methylene chloride is more important hazard because of chemical asphyxia. METHOD: NIOSH(National Institute of Occupational Safety and Health) Manual of Analytical Methods(NMAM) #1005 was used in sampling and analysis of methylene chloride. 4 air bases were surveyed. RESULT: Airborne concentrations of methylene chloride distributed lognomally. In aircraft paint stripping operation of 4 air bases, geometric mean(GM) of methylene chloride concentrations was 30.40+/-3.39 ppm (n=14) in personal samples and GM of area samples was 2.24 ppm (n=2). 5 of 8 samples showed breakthrough phenomenon. Breakthrough rate([back section]/[front section]) significantly correlated with airborne concentrations (p<0.01) and with detected amounts of methylene chloride(p<0.01). CONCLUSION: Airborne concentrations of methylene chloride in paint stripping process exceed the criteria level in many case(43%). Seriesed charcoal tubes must be used in methylene chloride sampling in compliance with NMAM.

Cardiorespiratory Responses of Pilots to Maximal Exercise Loading

BACKGROUND: To provide some fundamental physiological basis for the physical training of pilots to improve orthostatic intolerance, cardiorespiratory responses to the symptom-limited maximal exercise loading were studied in pilots and non-pilots, and the results were compared. METHOD: Cardiorespiratory reponses to the symptom-limited maximal exercise loading by Bruce protocol was studied in 11 pilots and 11 matched controls (non-pilots). RESULTS: Comparisons of various data at maximal exercise in the pilots with those in the controls revealed that RR, VE/M2, VE/VO2, VE/VCO2, VT/VC and VE/MVV as well as HR, VO2, O2 pulse and AT showed no significant difference. CONCLUSION: The fact that the aerobic power in the pilots is not superior to that in the controls seems to emphasisze the necessity of aerobic endurance training along with muscular strength training to improve orthostatic tolerance of pilots flying modern high-performance aircrafts.

Prevalence of PPNG in Seoul , Korea ( 1987 ) / 대한피부과학회지

The prevalence of PPNG among pretreatment isolates at a VD Clinic in Seoul has been studied and reported annually since 1981. In 1987, 649 strains of N. gonorrhoeae were isolated, among which 339(52.2%) were PPNGs. The prevalence of PPNG in Seoul is still increasing.

A Case of Paraffinoma / 대한피부과학회지

We experienced a 57-year-old male patient who have had multiple coin sized, erythematous, psinful, indurated ulcerations with purulent discharge on the right calf area since 10 years before. Previously he received injections of paraffin in the lesion site for correcting the thinning of right calf due to complication of pyoderma. Histopathologic examination showed "Swiss cheese" appearance of parsffinoma. Good result was obtained after treatment with surgical excision and split thickness skin graft.

Allergen Prick Test Reactivity in the Patients with Uriticaria and Atopic Dermatitis / 대한피부과학회지

This study was undertaken to investigate the skin sensitivity to 54 different allergens in 248 patients of 81 acute urticaria, 141 chronic urticaria and 26 atopic dermatitis, who visited in Department of Dermatology, College of Medicine, Chung Ang University Hospital from February 1986 to January 1987. The results were as follows . 1. The sex ratio of male to female of 248 patients with allergic state was 1.1: 1 (130: 118) and third and fourth decades occupied 56.5%. In regard to the duration of chronic urticaria, less than 1 year were 31.2% and between 1 to 3 years were 28.3%. 2. In acute urticaria, the prick test positive reactivity to allergens were in descending order to mite, household insect mixture, Trichophyton mixture, house dust, mold mixture C and silk, whereas in chronic urticaria ', mite, household insect mixture, house dust, cockroaeh mixture, Trichophyton mixture and silk and in atopic dermatitis ; mite, house dust, Trichophyton mixture, household insect mixture, mold mixture A and C. 3. The positive reactivities of allergens in patients with atopic dermatitis, chronic urticaria and acute urticaria were 69.2%, 52.5% and 35.8%, respectively. 4. The positive reactivity to compound allergens were higher than to single and the most frequent combinations were 2 to 5 allergens (85.4%). 5. Out of 54 allergens used in this study, 49 allergens were reactive and the most frequent group of allergens were house dusts (41.5%) and commonly involved allergens were mite (27.8%), household insect mixture (15.7%), house dust (13.7%), Trichophyton mixture (11.7%) and cockroach mixture(7.7%). 6. Common other allergic diseases combined with atopic dermatitis were rhinitis and bronchial asthma, occuring in 23.1%.