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Industrial odour control 5 Establishment of immission limits
5.1 General odour immission limitsThis guideline deal only with odour nuisances, which do not cause physical damage to the environment. Therefore the emission limits are derived directly from immission limits. The limit value for cellulose diluents specified in The Danish EPA Guideline 2/1978 can, however, still be applied to odour from these substances. Some odorants which otherwise harm the environment may be covered by other guidelines. For some of these substances (for instance sulphur dioxide), the limits recommended in these guidelines are dimensioned for outlets or cleaning measures. Aspects which influence the extent of odour nuisances As mentioned earlier the degree of annoyance caused by odour is determined by the odour intensity, the frequency and duration of the impact, and the acceptability. The annoyance felt by different people is also influenced by their perception of smell, which varies with time and with the conditions in which each individual is exposed to smell. Dimensioning of outlet and/or cleaning measure
Meteorological situations influencing dimensioning In Denmark meteorological conditions are for about 60% of the time neutral or moderately unstable. In much of the remaining time the meteorological conditions result in smaller ground level concentrations of odorants emitted through outlets. Only in very small percentages of time, meteorological situations result in higher concentrations at ground level. Some of these situations are difficult to describe and, thus, to make calculations for. When dimensioning requirements are fulfilled If the dimensioning requirements are fulfilled a minor part of the population living where the odorant occurs in concentrations corresponding to the odour threshold will, however, still be able to perceive the smell, even if this does not necessarily mean that they are annoyed, and even if, in practice, each of them is only exposed to the smell for smaller periods of time. Please note that the recommendation given above is used as a basis of calculation made with due regard to the frequency of different meteorological situations. 5.2 Addition of odour contributionsOdour contributions from one industrial plant must be added up. Odour contributed by several plants emitting substances with different odour properties can be dealt with separately. If several plants of the same type are expected in one area, plans must be made to ensure that the total emission from new and existing plants is limited so that the total immission concentration contribution does not exceed the values recommended in this guideline (see also section 7.3.).
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