6.1.4 Are Mold Counts Helpful?

Similar to pollen counts, mold counts may suggest the types and relative quantities of mold present at a certain time and place. For several reasons, however, these counts prob­ably cannot be used as a constant guide for daily activities. One reason is that the number and types of spores actually present in the mold count may have changed considerably in 24 h because weather and spore dispersal are directly related. Many of the common aller-genic molds are of the dry spore type—they release their spores during dry, windy weather.

Other molds need high humidity, fog, or dew to release their spores. Although rain washes many larger spores out of the air, it also releases some smaller spores into the air.

6.1.5 What Can Happen with Mold-Caused Health Disorders?

Fungi or microorganisms related to them may cause other health problems similar to an allergy. Fungi may lodge in the airways or a distant part of the lung and grow until they form a compact sphere known as a "fungus ball." In people with lung damage or serious underlying illnesses, Aspergillus may grasp the opportunity to invade and actually infect the lungs or the whole body. In some individuals exposure to these fungi can also lead to asthma or to an illness known as "allergic bronchopulmonary aspergillosis." This latter condition, which occurs occasionally in people with asthma, is characterized by wheezing, low-grade fever, and coughing up of brown-flecked masses or mucous plugs. Skin testing, blood tests, X-rays, and examination of the sputum for fungi can help establish the diag­nosis. The occurrence of allergic aspergillosis suggests that other fungi might cause similar respiratory conditions.

Inhalation of spores from fungus-like bacteria, called actinomycetes, and from molds can cause a lung disease called hypersensitivity pneumonitis. This condition is often asso­ciated with specific occupations. Hypersensitivity pneumonitis develops in people who live or work where an air-conditioning or a humidifying unit is contaminated with and emits these spores. The symptoms of hypersensitivity pneumonitis may resemble those of a bacterial or viral infection such as the flu. If hypersensitivity pneumonitis is allowed to progress, it can lead to serious heart and lung problems.

6.2 Biological agents and fungi types

A host of fungi are commonly found in ventilation systems and indoor environments. The main hazardous species belong to the following genera: Absidia, Alternaria, Aspergillus, Fusarium, Cladosporium, Cryptostroma, Mucor, Penicillium, and Stachybotrys. Various strains of these genera of molds have been implicated in being causative agents in asthma, hyper­sensitivity pneumonitis, and pulmonary mycosis.

Fungi commonly found in ventilation systems and indoor environments include Absidia, Acremonium, Alternaria, Aspergillus, Aureobasidium, Botrytis, Cephalosporium, Chrysosporium, Cladosporium, Epicoccunt, Fusarium, Helminthosporium, Mucor, Nigrospora, Penicillium, Phoma, Pithomyces, Rhinocladiella, Rhizopus, Scopulariopsis, Stachybotrys, Streptomyces, Stysanus, Ulocladium, Yeast, and Zygosporium. Eleven types of fungi are typi­cally found in homes: Aspergillus, Cladosporium, Chrysosporium, Epicoccum, Fonsecaea, Penicillium, Stachybotrys, and Trichoderma.