RESUMO
We describe two cases of respiratory allergy (asthma), which were difficult to diagnosis from an etiological viewpoint. The routine diagnostic tests were not able to determine the causal allergens, although the clinical history suggested that allergens were confined to restricted environments. Therefore, an aerobiological sampling by means of a battery-powered portable device was carried out. This approach allowed identification of the responsible allergens, which were Alternaria spores in one case and thuja pollen in the other. Once a targeted environmental care had been performed, the patients' symptoms rapidly improved and antiasthma therapy could be stepped down or discontinued. We suggest that, in selected cases of difficult diagnosis the presence of proximity allergens is suspected, aerobiological sampling with a portable device should be considered.