Page 1143 - Week 04 - Thursday, 1 April 1993
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NCDC design criterion of 65 dB(A) currently applying.
(b) It is unlikely that lead levels in air would exceed the National Health and Medical Research Councils guideline value of 1.5 micrograms per cubic metre (90-day average value). I understand the ACT Board of Health is proposing to measure airborne lead levels in Kitchener Street over a 3 month period commencing in April 1993.
Explanatory Notes on Terms Used:
(1) The term dB (A) means that the sound intercity is expressed in decibels on the A-weighted scale which is the most relevant to the human ear.
(2) The descriptor dB(A)L10 18hr is commonly used to describe. road traffic noise, and represents the arithmetic average of the 18 individual LA10, 1hr values between 6 am and midnight. The traffic floc. information used in calculating the descriptor value is normally the highest daily flow for the 18 hour period.
The descriptor is expressed in A-weighted decibels (dB(A)] and indicates the noise level which is exceeded for 10% of the time stated. The time interval used may be from 1 hour to 18 hours.
The measure is used to indicate the level of road traffic noise which should not be exceeded if specific maximum design noise values for the. interior of buildings are not to be exceeded.
The descriptor LA10, 18hr is used in planning to identify set-back and or attenuation requirements to minimise intrusion by traffic no.?se, particularly in residential areas.
(3; 90-day average value means the average value obtained .from a standard test carried out over period of 3 months, with readings taken over 24 hours on every 6th day.
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