4.2: Occupational Exposures

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Occupational Noise Exposure

Sound levels

When employees are subjected to sound levels exceeding those listed in Table D-2, feasible administrative or engineering controls shall be utilized. If such controls fail to reduce sound levels measure in decibels (dBA) within the levels of the table, personal protective equipment as required in Subpart E, shall be provided and used to reduce sound levels within the levels of the table.

Tabe D-2 - Permissible Noise Exposures

Permissible Noise Exposure
Duration per day(hours)	Sound Level dBA slow response
8	90
6	92
4	95
3	97
2	100
1 ½	102
1	105
½	110
¼ or less	115

In all cases where the sound levels exceed the values shown in Table D-2, a continuing effective hearing conservation program shall be administered.

When the daily noise exposure is composed of two or more periods of noise exposure of different levels, their combined effect should be considered, rather than the individual effect of each. Exposure to impulsive or impact noise should not exceed 140 dB peak sound pressure level.

Non-ionizing Radiation

Qualified and trained employees

Only qualified and trained employees shall be assigned to install, adjust and operate laser equipment. Proof of qualification for the laser equipment operator shall be available and in the possession of the operator at all times.

Exposure level for eye protection

Employees, when working in areas in which a potential exposure to direct or reflected laser light greater than 0.005 Watts (5 milliwatts) exists, shall be provided with anti-laser eye protection devices as specified in Subpart E of this part.

Warning signs

Areas in which lasers are used shall be posted with standard laser warning placards.

Beam shutters or caps

Beam shutters or caps shall be utilized, or the laser turned off, when laser transmission is not actually required. When the laser is left unattended for a substantial period of time such as during lunch hour, overnight, or at change of shifts, the laser shall be turned off. The laser beam shall not be directed at employees.

Environmental (weather) conditions

When it is raining or snowing, or when there is dust or fog in the air, the operation of laser systems shall be prohibited where practicable; in any event, employees shall be kept out of range of the area of source and target during such weather conditions.

Employee exposure limits

Laser equipment shall bear a label to indicate maximum output. Employees shall not be exposed to light intensities above:

Direct staring: 1 micro-watt per square centimeter;
Incidental observing: 1 milli-watt per square centimeter;
Diffused reflected light: 2½ watts per square centimeter.
A laser unit in operation should be set up above the heads of the employees, when possible. Employees shall not be exposed to microwave power densities in excess of 10 milli-watts per square centimeter.