Seasonal distribution of Aspergillus in the air of an urban area: Mexico City

The seasonal variation of Aspergillus in the atmosphere of Mexico City was determined, using an Andersen air sampler, at different times of the day, over a period of one year. Aspergillus represented a low percentage of the total mould count, 5%, 4%, and 2% in the morning, noon, and night respectively. It was possible only in the morning to observe a seasonal trend for Aspergillus, with high colony numbers during the dry season. However, the highest CFUm-3 were detected in April for the three sampling times of the day. Different percentages of negative growth plates were recorded during the sampling time, but a large percentage was recorded at noon. Multiple regresional analyses indicate that significant correlations exist between Aspergillus CFUm-3 and vapor pressure and temperature inversion in the morning, and with temperature and daily range of temperature at night. Fourteen species of Aspergillus were identified, but A. niger, A. fumigatus, and A. flavus were the most abundant.