Occupational noise-induced hearing loss in India

Abstract

Noise is the insidious of all industrial pollutants, involving every industry and causing severe hearing loss in every country in the world. Exposure to excessive noise is the major avoidable cause of permanent hearing impairment. Worldwide, 16% of the disabling hearing loss in adults is attributed to occupational noise, ranging from 7 to 21% in the various subregions. The estimated cost of noise to developed countries ranges from 0.2 to 2% of the gross domestic product (GDP). Noise-induced hearing loss (NIHL) is bilateral and symmetrical, usually affecting the higher frequencies (3k, 4k or 6k Hz) and then spreading to the lower frequencies (0.5k, 1k or 2k Hz). Other major health effects are lack of concentration, irritation, fatigue, headache, sleep disturbances, etc. The major industries responsible for excessive noise and exposing workers to hazardous levels of noise are textile, printing, saw mills, mining, etc. Hearing protectors should be used when engineering controls and work practices are not feasible for reducing noise exposure to safe levels. Earmuffs, ear plugs and ear canal caps are the main types of hearing protectors. In India, NIHL has been a compensable disease since 1948. It is only in 1996 that the first case got compensation. Awareness should be created among workers about the harmful effects of noise on hearing and other body systems by implementing compulsory education and training programs. There are very few published studies of NIHL in India. More extensive studies are needed to know the exact prevalence of NIHL among the various industries in India.

Frequency analysis of heavy earth moving machineries in a highly mechanised bauxite mine

“…The noise survey was conducted at three different workplaces / sites:  Loading &transportation(shovel6.5m 3 , dumper 50T, dumper 55T and pay loader8.7 m 3 ),  Dozing and drilling (dozer 520TPH, drill machine 6" hole dia, rock drill 5 Tonne and motor grader4.5m) and  Crushing & screening(crusher, hopper,drive house and belt tension carriage). Frequency analysis is required to have detailed information about noise produced by various machineries in various workplaces [12,14].…”

“…To assess whether a miner is exposed or not to a specific sound pressure level vis-a-vis the established noise standards, it is necessary to take exposure duration, noise levels, spectrum and frequencyinto account [2].Standard for assessing the occupational daily noise exposure has been proposed by the International Organization for Standardization (ISO) , ISO 9612: 2009(ISO, 2009 [3].Noise annoyance is normally predicted by the A-weighted sound pressure level L Aeq withfrequencies analysis for better results [4,5].Exposure to excessive noise levels results in noise induced hearing loss which is the second most common form of sensorineural hearing deficit, after presbycusis that begins at the higher frequencies (3 kHz to 6 kHz) and develops gradually [6,7].Excessive noise exposure in the workplace can limit workers' ability to communicate, hear warning signals and can affecttheir safety and productivity [8,9].A more significant risk is that continuous noise exposure increases the risk of noise induced permanent threshold shift (NIPTS) in their hearing, with implications for workers' health, employment prospects and overall quality of life [8,9,10]. The amount of hearing loss depends upon frequency and sound pressure level of noise, bandwidth of noise, duration of exposure each day, and number of years of exposures [11,12,13,14].Thus continuous monitoring & analysis of the noise levels and its control is much essential to maintain acoustic friendly environment [13,15,16].In the pastseveral decades, noise exposure of miners and noise reduction of sound source, have been studied by many researchers, while a limited study has been done on the frequency analysis of noise in bauxite mines [17,18,19].This article incorporates the findings of study carried out onfrequency analysis of machineriesat a bauxite mine, where L Aeq has exceeded 85 dB (A). Machineries at loading & transportation, dozing& drilling, and crushing & screening of the bauxite mine were selected for which the noise levelswere determined and frequency analysis wascarried out.…”

Comparing the Effect of Different Permissible Exposure Limits on Hearing Threshold Levels above 25 dBA over Six Months

“…Other comorbid conditions that may contribute to DALY such as stress, depression, hypertension, peptic ulcer, and chronic fatigue are the non-auditory effects of noise-induced hearing loss. The progression of this occupational disease is reliant on three factors: frequency; intensity; and duration of exposure to loud noise [2] . There are different views with regards to levels of noise that may lead to this slow and irreversible occupational malady.…”

Effect of Excessive Noise Exposure on Granite Factory Workers

“…World Health Organization (WHO) describes that exposure to excessive noise is the major avoidable cause of permanent hearing impairment. 8 Occupational Noise Induced Hearing Loss (ONIHL) is the second most leading cause of hearing loss after age-related hearing loss. 9 A 16% of the hearing loss in adults worldwide is attributed to occupational noise exposure.…”