Analysis In The Influencing Factors On Hearing Loss Of Rail Locomotive Crew

BackgroundAs one of the important means of transportation, rail transport plays an important role in national economy, social development and the improvement of people’s living standards. By the end of the year of2012, China’s railway operation mileage had reached98,000kilometers, ranking the second in the world; high-speed rail operation mileage,9,356kilometers, ranking the first in the world. As the driving force producer, a locomotive vehicle is an important element in rail transport. With the development in economy, science and technology, the trains run faster and weigh lighter. Undoubtedly, it is arousing more concern about the stability and security of the railway locomotives.With the increase in speed, the noise generated by locomotives is getting more and more serious. Noise can do a great harm on human body. The damage made by noise on human body is mainly in the auditory system. This damage is very special. Noise can not only cause deafness, but also cause non-specific damage to the body, such as dizziness, headache, tinnitus and other symptoms. Noise can also undermine the normal operations of the locomotive crew. More specifically, it can cause unresponsiveness and decrease work efficiency and even cause traffic accidents.Due to the particularity of the work of the locomotive crew, they continuously work day and night with shift work. The noise exposure of the locomotive crew in one shift is quite different from that of the workers in one shift in other fields.Therefore, it is of great significance to conduct a further research in the effective interior counter-measurers against the noise in locomotives, on the basis on analyzing the influencing factor of noise on hearing loss of the locomotive crew.ObjectiveThe research aims at analyzing the influencing factors of noise on hearing loss of locomotive crew, exploring the relations between noise hearing loss and the extent of noise exposure and finding the relations between hearing loss and length of service, age, level of education, smoking, alcohol drinking in order to provide scientifically medical foundation for preventing and controlling the occupational noise hearing loss and for further studies in the effective interior noise control measures to protect the health of the locomotive crew to ensure the safety of transportation.MethodsIn2012, the researchers did physical checkups for1027male locomotive drivers. They also analyzed their personal elements such as age, level of education, smoking, alcohol drinking. Questionnaire was made by a team of full-time professional doctors in occupation disease. They also inquired, examined and registered. Registration form was recorded by the trained professionals to give a double check for the assurance of the truth of the data. This survey introduces an electric auditory equipment to determine workers’noise hearing on job, sound-level testing device to observe noise strength. By means of χ2testing, T testing and Logistic analysis method to analyze the relations between noise hearing loss and the extent of noise exposure, and forms a report on such effects on noise hearing loss as age, level of education, smoking and alcohol drinkingResults1. In the research, the noise intensity in the locomotive cab tested involves eight models of trains and74locomotives. The results show that the noise mean is74.3dB (A); a standard deviation is5.3; the minimum value is65.8dB (A); the maximum value is88.5dB (A);with15cabs exceeding the standard value, the rate of exceeding reaching20.3%.2. Pure tone audiometric test conducted in two groups of workers, it is found the rate of hearing loss is up to22.1%among1027worker exposed to noise, much higher than8.5%--the rate among the reference group of550workers, the difference being significant (P<0.05).3. With the increase in the length of service, age and Cumulative Noise Exposure (CNE) growth, the number of locomotive crew tested and the rate of the occurrence of noise deafness are also increasing, the difference being statistically significant (P<0.001). After trend chi-square test, it is found that with the increase in the length of service, age and CNE growth, the rate of occurrence of hearing loss on workers tends to increase, this trend being statistically significant (P＜0.001).4. With the observed object and noise-induced hearing loss in audiometer results as the dependent variable, with CNE, age, culture, smoking, alcohol consumption as the independent variables, after the multivariate logistic analysis, the results show that CNE, and age are of significance in statistics (P<0.05), while other variables are not statistically significant, indicating that the CNE and age are risk factors for hearing loss.5. Single factor logistic regression analysis in length of service, with the observed object and noise deafness showed that:length of service is statistically significant (P <0.05). This means that the length of service is the risk factor for the observed object and noise deafness.6. The model formula for the connection between the occurance of noise deafness and the CNE:Y=0.758*[(X-75)/5]^2-0.9874*[(X-75)/5](R2=0.9972). Calculated when5%of individuals have noise deafness, the CNE is89.50dB (A)year. If eight hours per day exposed to noise with the intensity measured in the site, CNE formula (2) is used to calculate T-the year exposed to noise when5%of individuals have noise deafness. ①Calculated based on74.3dB (A), the mean value of noise intensity in locomotive cab, T=33years.②Calculated based on65.8dB (A), the minimum value of noise intensity in locomotive cab, T=234years③Calculated based on88.5dB (A), the maximum value of noise intensity in locomotive cab, T=1.3yearsConclusionNoise is one of the occupational hazards on locomotive drivers. The locomotive drivers exposed to noise for a long-term operation without proper protection measures, will suffer temporary or permanent hearing loss or even deafness. By the investigating the hearing of locomotive drivers, it is found that the hearing loss rate of locomotive drivers is positively correlated with the length of service, age, CNE, which means that with the extension of the length of service, the growth of age and the increase of the CNE, hearing loss it getting deteriorating.The model formula for the connection between the occurance of noise deafness and the CNE, the CNE is89.50dB (A) year, the year exposed is33years. The length of service for20years, the age of locomotive drivers at age of40should pay close attention to changes in hearing. Such as the observation object should be the regular physical examination and dynamic observation. That speech frequency hearing loss should be promptly removed from the work place as soon as possible.It is also found that if the noise in the locomotive cab is handled improperly, it can not only damage the hearing of locomotive crew, but also can affect the mood and the ability to work, and even thereby endanger the safety of the running train. By taking comprehensive measures to control noise intensity, to strengthen the education of hearing protection, to regulate occupational health examination, to enhance workers’ self-protection awareness, to reduce smoking and alcohol-taking and other bad habits, to reduce the exposure time of workers in excessively noise-intensive workplaces, to reduce the total length of service in noise exposure and pay enough attention to good health care, and gradually improve the prevention and control of occupational diseases in order to effectively protect the interests of the health of the workers.