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BOC Immingham Dissolved Acetylene Project Environmental Statement: Vol. 2 Main Text
Table 6.7 Environmental Assessment Levels for Air
Pollutant Long Term (µg/m 3 ) Short Term (µg/m 3 )
Acetone 18,100 362,000
Ammonia 180 2,500
Hydrogen sulphide 140 150
Phosphine - 42
6.90 In addition, a long-term EAL for ammonia of 3 µg/m 3 has been set for higher plants (i.e. non lichen
communities).
6.91 Screening calculations were undertaken at the Scoping stage, following the methodology
described in Annex F of the EA’s H1 guidance. The dispersion factors for an effective stack height
of zero (a very conservative approach) have been used, assuming that all of the substances are
released from a single, low level point source with no buoyancy or momentum (a reasonable
approximation given the absence of sensitive receptors in the immediate vicinity). The emission
rates (g/s) were derived assuming operation for 4,000 hr/yr (50 weeks per year, 5 days per year
and 16 hours per day).
6.92 The results of the screening assessment are presented in Table 6.8 for the health-based EALs.
These results use the maximum ground level concentrations and are therefore an overestimate of
concentrations that would occur at the nearest sensitive receptor.
Table 6.8 Results of H1 Screening for Emissions to Air
Pollutant Emission rate PC,
µg/m 3
PC as Percentage
of EAL
kg/yr g/s L/T S/T L/T S/T
Acetone 118 8.2x10 -3 1.21 31.96 0.01 0.01
Ammonia 2.17 1.5x10 -4 0.02 0.59 0.01 0.02
Hydrogen sulphide 0.06 4.2x10 -6 0.001 0.016