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BOC Immingham Dissolved Acetylene Project Environmental Statement: Vol. 2 Main Text
Chemical Symbols
Symbol Definition
CO carbon monoxide
NO2
NOx
nitrogen dioxide
oxides of nitrogen
PM particulate matter
PM10
PM2.5
SO2
Units
particulate matter with a diameter of less than 10 µm
particulate matter with a diameter of less than 2.5 µm
sulphur dioxide
Unit Definition
% percent (per one hundred) (concentration)
μg microgramme (1 x 10 -6 g) (mass)
μg/m 3 microgramme per cubic metre (concentration)
°C degree centigrade (temperature)
dB(A) Decibel is the unit of sound with 0 dB(A) being the threshold of
hearing and 140 dB(A) being the threshold of pain. The (A) denotes
that it is ‘A’ weighted which is a frequency weighting which
approximates to the human response to sound. Human hearing is not
equally sensitive at all the frequencies being less sensitive at the low
frequencies (8,000 Hz). (sound)
g gramme (mass)
hr hour (time)
ha hectare, equivalent to 10,000 m 2 (area)
Hz Hertz (frequency; the number of cycles per second)
kg kilogramme (mass)
km kilometre (length)
kV kilovolt (electrical potential)
kW kilowatt (power)
l litre (volume)
LAeq, t
continuous equivalent noise level of a time-varying noise; the steady
noise level (in dB(A)) which, over the period of time under
consideration, contains the same amount of (A-weighted) sound
energy as the time-varying noise over the same period of time (t)
(sound)
LA90 (dB) background noise level, the noise level exceeded for 90% of the
measurement time (sound)
5100935.404 Environmental Statement August 2011 xv