Atmospheric concentrations and intradiurnal pattern of Alternaria and Cladosporium conidia in T,touan (NW of Morocco)

Fungal spores of Alternaria and Cladosporium are ubiquitous components of both indoor and outdoor air samples and are the main causes of human respiratory allergies. Monitoring these airborne fungal spores during 2009-2014 was carried out by means of Hirst-type spore trap to investigate their airborne spore concentrations with respect to annual load, seasonality and overall intradiurnal pattern. Alternaria and Cladosporium spores are present throughout the year in the atmosphere of T,touan, although they show seasonal variations. Despite important differences between years, their highest levels presented a first peak during spring and a higher second peak in summer or autumn depending on the year. The spore concentrations were homogeneously distributed throughout the day with slight increase of 7.6 and 3.7% on average between 12-14 and 14-16 h for Alternaria and Cladosporium, respectively. The borderline of 3000 sp/m(3) of Cladosporium linked to the occurrence of allergic diseases was exceeded between 13 and 31 days. Airborne spores of Alternaria overcame the threshold value of 100 sp/m(3) up to 95 days, suggesting that Cladosporium and Alternaria could be clinically significant aeroallergens for atopic patients.