NOISE

Noise:  Types

 Impulsive noise:

• High intensity for low duration (firecracker, nuclear/mining explosion, gunshots, hammer blow, etc.)
• Characterized by noise levels more than 40dB with a duration of less than a second

 Continuous noise:

• produces continuously
• Noise generated by a machine that keeps running without interruption, e.g. generator, vehicle, etc.

 Intermittent noise:

• Noise generated with a break. E.g. drilling machines in carpenter work, grinders, etc.

Major Sources

 Natural sources – lightening, wind, rainfall, etc

 Man-made sources

• Domestic / home appliances
• Industries/factories
• Transportation
• Occupational
• Social and religious events
• Public announcement

SAFETY LIMITS- How loud is too loud?

 The maximum exposure limit is 85dB for eight hours a day

WHO guidelines

 The WHO guidelines for community noise recommend

• less than 30 dB(A) in bedrooms during the night for a sleep of good quality
• less than 35 dB(A) in classrooms to allow good teaching and learning conditions

 The WHO guidelines for night noise recommend less than 40 dB(A) of annual average outside of bedrooms to prevent adverse health effects from night noise.

Impacts of Noise Pollution

The degree of harmful effects depends on its

• intensity
• exposure time
• location of a person
• nature of the work performed by a person and his individual characteristics

Control over Noise Pollution

• Legal / Administrative control
  • Airports, railway stations, and bus parks should be away from residential areas
• • The “No horn” policy should be strictly implemented in areas like schools, offices, hospitals, etc.
• • Regulation of using loudspeaker (time-bound)Bann of pressure horn
  • Promote new technology that is noise proof or least noise generating

• Mechanical / Engineering control
  • Source control – use of sound absorbing materials, acoustic treatment to machine surface, limiting the operational timing
  • Control over vibrations
  • Sound insulation
  • Sound absorption
  • Vibration damping

• Personal control (sensitization, use of PPE, etc.)

Control techniques

• Noise can be controlled:
  • Reduce noise at the source
    • Is the most effective to eliminate noise at the source.
  • • Noise can be controlled at the source of generation by :Maintenance of automobiles / regular servicing / lubrication of machines, tightening the loose unit / plastic or rubber buffer on furniture to avoid noise cause due to dragging of furnitureControl over vibrations (proper foundations/ rubber padding to reduce shock)Prohibition of uses of loud speakers in habitant zones, pressure horns, ban on unnecessary blowing of hornsTurning off  the engine at rest
    • Modification of manufacturing designs like enclosing the engine parts within proper noise insulating materials

• Block the path of noise
  • Constructing sound-proof buildings
  • Green belt development (Plantations) : helps in controlling by absorbing high frequency sound waves

• Increase the path length
  • Moving factories and industries (noisy operations or machinery) away from residential areas / people

• Protect the recipient
  • Receiver of noise must be safe guarded by using of PPE appropriately
  • Use of ear plugs

Noise Pollution – Management Principles

• Prevention principle
• Precautionary principle
• Polluter pays principle
• Without an adequate policy framework and adequate legislation it is difficult to maintain an active or successful noise management program
• The goals are more readily achieved if the interconnected government policies are compatible and coordinated (if issues crosses different areas of government policy)

Legal provisions

• There are few laws that provide provisions on noise pollution in Nepal
  • The Civil Aviation Act, 1958 provides a provision to control airplane noise
  • The Explosives Act, 1961 is to regulate noise from the use of explosives to some extent
• But the major noise pollution in the city is from vehicular traffic and textile/metal cutting industries, have not been covered by any legal framework in Nepal
• Provisions controlling noise from other range of accessories like power tools, air conditioners, amplified music should also be considered