Outdoor environmental levels of Aspergillus spp. conidia over a wide geographical area

Abstract

Unfortunately, little information is available on the 'normal' air and water load of Aspergillus spores and their seasonal changes. We describe the air and water load of Aspergillus spores across the province of Madrid (Spain). We collected samples of air and water (332 samples of air and 148 of water) from selected points and taps (urban and rural environment) in summer, autumn, winter and spring. Temperature, wind speed and humidity at each point were obtained. We collected a total of 369 Aspergillus spp. isolates: 200 A. fumigatus, 94 A. niger, 40 A. flavus, 16 A. nidulans, two A. terreus, and 17 Aspergillus spp. We always found more isolates in the urban environment than in the rural environment (P=0.11). This was also true of A. fumigatus (P=0.014). The autumn collection yielded more isolates than that of the other seasons. The level of conidia in air varied from 0 to 85 c.f.u./m3: 6.4 c.f.u./m3 in summer, 12 in autumn, 2.5 in winter and 1.3 in spring. Changes in atmospheric parameters influenced the levels in air. None of the water samples were positive. Counts of Aspergillus spp. spores were always under 85 c.f.u./m3. Public water does not seem to contain Aspergillus spores.