NOISE
Noise is an unwanted sound. When people are exposed to high noise level, the following noise induced disorders/problems take place.
1. Hearing loss: Excessive noise damages the hair cells in the cochlea, part of inner ear, leading to hearing loss.
2. Physiological: Excessive noise can cause blood pressure.
3. Work-related stress: noise in the work environment can cause mental stress.
4. Increases the risk of accidents due to the difficulty in listening to safety alarm.
5. Annoyance
6. Dilation of pupil
The sensitivity of the human ear is not uniform. Our hearing mechanism is more sensitive between 1000 HZ to 4000HZ. The decibel measurement is done in this frequency range and it is mentioned as dB (A)
The noise intensity is measured in decibels. It is not the intensity that determines whether the noise is hazardous, but the time of exposure is important and it decides the hazard.
There are some work places in industries where high noises exist.
They are:
Compressor and engine room 100-120 dB
Reactors and digesters 90-120 dB
Large electric motors and drives 90-110 dB
The table below shows the permissible noise level in decibels and the time duration of its exposure.
Permissible Noise Level Exposure
The louder the noise, the short should be the exposure time, a worker may be exposed to a noise level of 90 dB for 8 hours per day. Anything beyond this limit requires hearing protection.
If engineering control and work practices do not lower the noise level within this range, appropriate PPE should be worn to protect the employees from the excessive noise. PPE reduces the amount of noise that gets through the ear.