Environmental challenge

A variety of organic dusts and chemicals encountered in our environment are capable of provoking a response in the lung. Frequently, they produce transient or reversible physiologic changes that may obscure the diagnosis. The patient may fail to recognize a causal relationship with a specific exposure with late-onset reactions and the development of symptoms remote from the exposure. A thorough evaluation of the individual's total environment and symptoms, with particular reference to their time course, is essential in making the diagnosis. Removal of the worker from a suspected environment, with serial clinical and physiologic monitoring to demonstrate improvement, or return to the workplace with similar studies, can be helpful in establishing a causal relationship. When a specific agent can be identified, a controlled inhalation challenge in the laboratory is the procedure of choice. Once a causal relationship has been established, the individual should be removed from exposure or the implicated agent eliminated.