Effects of noise exposure among industrial workers in power plants of the National Electricity Company in N’Djamena, Chad

Abstract
Background
Noise pollution, unwanted or excessive sound, is one of the most common nuisances in industrial sectors. In the city of N’Djamena, Chad, workers in power plants are exposed to very high levels of noise, which could have deleterious effects on human health. The purpose of the study is to determine the level of noise pollution and its repercussions in a population of power plant workers.

Results
Ninety-two (11.5%) of the 800 workers were included. Their sex ratio was 88 men: 4 women with an outcome of 22. The age range was from 23 to 64 years with an average of 38.7 ± 9.0 years. Forty-seven (51.1%) of the employees had received occupational safety training. The average noise level in the machine rooms was 113.5 ± 4 dB(A). The average duration of exposure to noise was 10.8 ± 8.5 years. Personal protective equipment was worn regularly in 85.9% (n = 79). The consequences of noise pollution were auditory fatigue (38%; n = 35), tinnitus (32.6%; n = 30), hearing loss (15.2%; n = 14), nervousness (45.7%; n = 42), headache (33.7%; n = 31), raised voice (27.1%; n = 25), and insomnia (14.1%; n = 13).

Conclusions
The level of noise pollution is relatively high in power plants in N’Djamena, Chad. Hearing effects and an altered quality of life are observed among industrial workers. The acquisition of machines with regulated noise levels is desirable. The audiometric test should be integrated into the follow-up assessment of all employees.