Cladosporium is a kind of mold that affects both outside and inside the house. It has around 40 species, which are found naturally around potted plants. They thrive in the soil and decaying plants. On the other hand, Cladosporium may occur as plant pathogen.

According to studies performed in North America and Europe, the spores of Cladosporium are circulating in the atmosphere the entire year. However, their concentration or population is extremely low during winter. They are highly present during summer with daily peaks ranging from 2,000 to 50,000 spores per cubic meters of air. The growth of different Cladosporium species within homes and other buildings depends on the concentration from outside environments. The concentration may also be influenced by the indoor sources of the growth.

Common Cladosporium Species

Cladosporium species grow as secondary colonizers of walls within indoor environments. They appear after the development of primary molds such as Aspergillus versicolor, Wallemia sebi, and certain species of Penicillium. Cladosporium is commonly found or grows on wet or damp building materials. These usually include acrylic paint, gypsum board, damp wood, and wet insulation within cooling units. The most common Cladosporium species include the following:

1. Cladosporium macrocarpum - This cosmopolitan species is commonly found in soil, dead plants, seeds, and juice concentrates of apples, and indoor air.

2. Cladosporium cladosporioides - This is another cosmopolitan species that can be commonly found in the air, soil, textiles, paint, and meat.

3. Cladosporium sphaerospermum - This is one of the most commonly encountered species. It can be commonly found in the soil, acrylic paint, air, gypsum board, painted wood, dust from mattresses or carpets, wet insulation in cooling units, HVAC fans, textiles, paint, and some food sources.

4. Cladosporium herbarum - This is perhaps the most common species of the Cladosporium. It is found on textiles, dead woody and herbaceous plants, paper, rubber, and different food sources. This species can be found in indoor areas such as the floor, mattresses, carpets, wet walls that are painted with acrylic, wallpaper, filters, fans, and HVAC insulation. C. herbarum is considered as the most well-known airborne mold spores. It is capable of developing in different temperature ranges. As a matter of fact, there have been reports of meat spoilage within cold storage.

The Effects of Cladosporium

Most Cladosporium species are not pathogenic to human beings. However, there are isolated cases, especially to immunocompromised patients. On the other hand, Cladosporium species are widely known to possess the capability to stimulate allergic reactions. This is common to individuals that are highly sensitive. Prolonged and heavy exposure to the airborne spores of this mold species can lead to chronic asthma and allergic reactions. There is an observed clinical significance to a concentration threshold of 3,000 spores per air cubic meter.

The reactions of an individual to the concentration of the airborne spores depend on his or her health conditions. People with weak immune system easily acquire allergic reactions even if the spore concentration is low. Like other mold spores, the spores of Cladosporium are very small, microscopic even. Because of this, they are easily breathed into the person's alveoli and terminal bronchi.