Environmental odours have a great amount of complexity because they are not considered as pollutants by having low levels of detection and concentration. They may cause impacts in population quality of life, by generating nuisance and discomfort. This situation may be more harmful with the existence of an urban agglomeration nearby an emission source. The Human nose can quickly detect odours that individuals are subjected, but the interpretation and verbalization are very difficult to make. Assessment techniques were used with quantitative and qualitative forms in two monitoring campaigns, one in summer and other in winter. This dynamic was held in a case study in a community with an urban waste treatment operator in which the surroundings make individuals perceptions of "rotten cabbages/rotten eggs" kind of odour. The Observers Panel (OP) monitoring last 92 days with 137 odour records in which 65% were from the kind of "rotten cabbages/rotten eggs". Hydrogen sulphide (H2S) samplers results assured extremely low concentrations below the emissions limit value (5 mg/Nm3), with 0.3 μg/m3 average concentration in the summer period and 1.0 μg/m3 in the winter time. In the second monitoring campaign, the possibility of the "rotten cabbages/rotten eggs" kind of odour to be perceived by the sensitive receivers was very high due to the OP and the H2S concentrations results. This was even higher in the locations of the OP were near the emission source. The weak dispersion conditions in this campaign led to higher concentrations levels of H2S. The dispersion model results indicated that, on the analyzed days, the odour plume had dispersed to the locations where the sensitive receptors made their assessments.