Pollen and spores in the air of a hospital out-patient ward.

BACKGROUND Aerobiological studies of interest to the allergy specialist are routinely carried out using information from outdoor traps. However, most of our time is spent indoors and it is often the content of this air that is responsible for allergic phenomena. MATERIAL AND METHODS The air of a hospital outpatient ward was analyzed using two portable volumetric aerobiological traps, one at floor level and the other at a height of 1 meter. Both spores and pollen grains were counted and their values were compared with those outside the building. RESULTS AND CONCLUSIONS Twenty types of pollen grains were found. Their concentrations ranged from 2.7 and 25.1 grains/m3, with the most frequent being (in order) grasses, evergreen oak (holm and cork oaks), water plantain, and olive. Twenty two different types of spores were found with concentrations of between 175.0 and 1395.8 spores/m3 and the most frequent were Cladosporium, Ustilago and basidiospores. No significant differences were found between the floor level and the meter-high measurements. Comparison with outdoor levels showed that the three most abundant pollen types were correlated, with a ratio of 30:1 between indoor and outdoor levels. For the spores and fungi propagules, the indoor:outdoor ratio was highly variable, depending on the type. Thus, for Aspergillus-Penicillium spores, the concentration was even higher indoors than outdoors, although for most types, lower levels were found indoors, with a mean outdoor:indoor ratio of 4:1. We argue that this relationship reflects the presence of indoor spore sources. Rainfall was correlated with a decline in pollen levels and a rise in spore levels.