ABSTRACT
The respiratory system is continually exposed to particles in the form of organic and inorganic dusts, pollens, fungal and bacterial spores, and viruses, despite a range of physiological adaptations within the respiratory tree. Some of the inhaled particles will be benign, but others will have the capacity to irritate mucous membranes, induce inflammation, with or without the concomitant induction of an immune response, or infect the host. Individuals may present with frank disease if infectious, or if noninfectious, with a variety of acute local symptoms, which may range from cough, airflow limitation, bronchial hyperreactivity, and immunity, depending on a variety of factors, such as dose, duration of exposure, genetic background, and ‘‘foreignness.’’ In some circumstances, generalized symptoms, including toxic fever, influenza-like symptoms, joint pains, dermatitis, and neurological symptoms may also appear. Such symptoms may then be associated with the clinical syndromes of asthma, occupational asthma, allergic alveolitis, and chronic bronchitis (1).
