It’s well established that airborne mold spores contribute to respiratory disease and allergic reactions in humans. Mold spores are everywhere and we inhale them every minute both when we’re indoors and outdoors. In cold countries airborne mold spores is highest during summer. During winter, the spore concentration outdoors is very low or absent altogether. In warm countries concentration of airborne spores may vary with the season (rainy or dry season) but there are spores present outdoors throughout the year. Usually the spore concentration indoors is lower than outdoors. However, in buildings with mold problem, the spore concentration could be very high.
Allergic reactions caused by mold spores
Inhaled mold spores can cause a number of health problems. Susceptible individuals react to proteins in the spore wall resulting in development of runny nose and eyes (allergic rhinitis) and asthma-like symptoms. Prolonged exposure to unusually high levels of spores can result in the development of allergic alveolitis.
Allergenic mold Spores
Spores commonly associated with allergy outdoors include spores of Cladosporium, Sporobolomyces, Didymella, and Alternaria. In buildings without mold problems, the same spores found outdoors would be present indoors but in lower levels than in outdoors. In buildings with mold problems a mix of species commonly found indoors and outdoors would be found. The indoor species would be in higher concentrations indoors than in outdoors.
In an indoor occupational environment the types of molds present would be determined by the indoor conditions and the work being carried out. For example in a compost facility thermotolerant fungi such as Aspergillus fumigatus would be present. Mold spores of some species such as Cladosporium and Penicillium may be detected in high numbers in air samples while others such as Eurotium, Wallemia, and Penicillium may be abundant in dust.