Introduction

Similar to many overseas cities with dense population and intense economic activities, noise is one of the environmental problems in Hong Kong.

When the Kai Tak Airport was operating, about 380,000 people were being exposed to severe aircraft noise. This situation has been drastically improved with the relocation of the airport to Chek Lap Kok since mid 1998.

Nonetheless, about a million people are still exposed to high levels of traffic noise. Various other activities such as construction, cargo handling, industrial and commercial facilities all generate noise that can result in speech interference for classrooms during daytime and sleep disturbance for the general population at night.

The following table shows the population exposed to severe traffic and aircraft noise :

Population Exposed to Severe Traffic and Aircraft Noise

Noise Type

Estimated
Population
Affected

Noise Standard

Traffic

1 000 000

L₁₀ (1 hour)⁽¹⁾
> 70 dB(A)

Aircraft

200

NEF⁽²⁾ 25

Legend
(1)	L₁₀ is the noise level exceeded for 10% of the 1 hour period. It is generally used to describe traffic noise during the hour of peak traffic flow.
(2)	NEF or Noise Exposure Forecast is an aircraft noise descriptor. It is a complex composite measure of exposure to aircraft noise, which takes into account the maximum flyover noise level, the duration and tonal characteristics of the flyover and the number of aircraft movements in both the daytime and nighttime period.