The characterisation of noise levels in various throughput abattoirs during the slaughtering of different species

Abstract

Occupational noise affects industries in many countries around the world, and there is strong evidence from previous research linking it to noise-induced hearing loss (NIHL). More than 30 million workers in the United States of America alone were exposed to hazardous noise at the workplace before 1998. In South Africa, workers are not supposed to be exposed to a noise rating limit at or above 85dB(A). Abattoir employees are subjected to high noise levels when compared to the occupational noise rating limit of 85dB(A). Noise is generated from various mechanised and manual processes and activities in the abattoir during the slaughter of different animal species. Noise sources include conveyers, circular saws, air conditioners and pumps, pneumatic and other mechanical equipment. The aim of this study was to characterise noise exposure in different grades of abattoirs during the slaughter of cattle and sheep. The grading of abattoirs was previously done according to Grade A-E. Grade A-C is now referred to as high throughput abattoirs while Grade D and E are referred to as low throughput abattoirs. Personal and environmental noise exposure levels of workers in Grade A, C and D abattoirs in the Free State were therefore investigated. Noise measurements were done in accordance with the methods stipulated in the South African National Standards (SANS) Code of Practice 10083. Environmental and personal sampling were conducted with a calibrated Type 1 Quest integrated sound level meter (ISLM) and a Quest noise dosimeter respectively. Calibration was checked before and after taking measurements to ensure reliability and validity of results. The average noise exposure level in the high throughput abattoirs was above the recommended standard of 85dB(A). In the low throughput abattoirs the noise exposure levels were below this level. There were no statistically significant differences between the noise exposure levels during the slaughter of different species (P>0.05), or between Grade A and Grade C (P>0.05). There was a statistically significant difference (P<0.05) however between Grade A and Grade D noise exposure levels. The results indicate that workers in Grade A and C abattoirs are exposed to unacceptable noise levels. Further research is recommended to include all categories of abattoirs and to determine the impact of noise exposure on the worker’s hearing in order to develop strategies to protect employees from the effects of excessive exposure to noise.