Noise

Too much noise can damage hearing. Continuous or periodic noise can be harmful.

Health effects

• Temporary hearing loss: This may last for minutes, hours or days. Normal hearing does return. 
  
  
• Permanent hearing loss: This usually develops gradually from being exposed to high levels of noise over a long period of time. 
  
  
• Other effects: Noise can cause fatigue, nervousness and increased blood pressure, which can lead to problems such as heart disease.

Finding noise hazards

You do not need fancy equipment to know if you are exposed to noisy conditions. Your hearing may be affected if:

• it is too noisy to hear your co-workers at arms-length; 
  
  
• you have to turn the volume up on the TV or radio; 
  
  
• you get a ringing in your ears after working in noisy areas; and/or 
  
  
• family, friends and co-workers notice that you have more trouble hearing them.

Measuring sound

The level of sound is measured in units called decibels. The abbreviation for decibels is dB. On the decibel scale, each time the number of decibels goes up by three, the level of the noise is doubled. In other words, 93 decibels is a noise that is twice as loud as a sound that is 90 decibels. Examples of common noises and their decibel levels are shown in the chart below.

Controlling noise hazards

Substitution

Use equipment that makes less noise.

Engineering controls

Noisy machinery can be enclosed, isolated or rigged with equipment to muffle sound. Acoustical building materials and carpeting absorb sound indoors.

Work practices (administrative controls)

• Rotate jobs to reduce the amount of time workers are exposed to noise. 
  
  
• Move workers away from noise. 
  
  
• Keep equipment lubricated and in good working order.

Personal protective equipment

There are different types of hearing protection that workers can wear. See Figure 1. Ear plugs are worn in the ear and must fit the worker’s ear. They should only be worn in healthy ears. Foam plugs should be soft and springy. They must be compressed so they can expand after inserting in the ear. The other common type of hearing protection are earmuffs that are worn outside the ear. Earmuffs require a good seal to be effective.

Figure 1 WARNING!!! Ear plugs or muffs make it difficult to hear warnings from co-workers, alarms or other warning signals. You should be able to hear alarms when wearing protection.

Laws (OSHA standard - 29 CFR 1910.95)

The OSHA noise standard limits the amount of exposure to noise to 90 decibels averaged over an 8-hour day. This means the louder the noise, the less time workers can be exposed. The chart below shows the amount of time that workers can be exposed to different decibel levels of noise.

WARNING!!! Legal does not always mean safe!!! Hearing damage can begin at levels as low as 80 dB over an 8-hour day. Just as with chemical exposure limits, you can suffer harm even when your employer is obeying the law.

All work areas that might be over 85 dB must be measured for noise. If noise levels are above 90 dB, the employer must take steps to bring down noise levels. The employer must try to reduce noise below 90 dB before relying on ear plugs or other personal equipment.

If exposure to noise averages above 85 dB for a shift, the employer must have a hearing conservation program. This includes providing employees with hearing tests and hearing protection.