Outdoor allergenic fungal spores: comparison between an urban and a rural area in northern Portugal

Abstract

Background: The frequency and concentration of many airborne fungal spores associated with respiratory allergy symptoms are influenced by geographical and climatic characteristics.

Objective: The aim of this work was to monitor the distribution of 11 potentially allergenic fungal spore types in 2 regions with different urbanization levels in Northern Portugal: Porto (urban area) and Amares (rural area).

Methods: Airborne fungal spore levels were monitored from 2005 to 2007 using Hirst-type spore traps. The Spearman correlation test was used to analyze the influence of meteorological factors (temperature, relative humidity, and rainfall) on spore concentration. Meteorological data from both areas were compared using the t test, and spore concentrations were compared using the sign test.

Results: In both areas, Cladosporium, Agaricus, Aspergillus/Penincillium, Altemaria, Coprinus, and rusts were the most abundant fungal types observed. Most of the analyzed spore types presented maximum values during the summer months, with the exception of Polythrincium, Stemphylium, and Torula, which reached a peak earlier in the year, whereas Aspergillus/Penicillium and Botrytis showed a wider distribution. Temperature had a positive effect on most spore concentrations, and relative humidity and rainfall negatively influenced concentrations ofAlternaia, Cladosporium, Epicoccum, and Torula.

Conclusions: The concentration of all selected spore types was higher in the rural than in the urban area, with higher values registe summer and autumn and lower values found during winter and spring. rainfall, influence airborne concentrations of major allergenic fungal spores.