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Causes and Incidence The cause is prolonged exposure to airborne asbestos particles. Susceptibility increases with increasing length and intensity of exposure. The incidence is greatly increased by chronic occupational exposure. Families of workers are also at risk from fibers carried home on clothing. The general public is at risk from long-term exposure to asbestos dust in old buildings in which asbestos was used as insulation, or from asbestos in shingling or building material.

Disease Process Asbestos particles are deposited on bronchiole or alveolar walls and are ingested by cells, leading to an edematous process in the wall that results in nonnodular alveolar and interstitial fibrosis, reduced lung volume and compliance, and impaired gas transfer.

Symptoms Symptoms begin with exertional dyspnea and decreased exercise tolerance. As the disease progresses, dyspnea is chronic even at rest and a dry cough may develop.

Potential Complications Asbestos is a cocarcinogen with tobacco, and asbestos workers who smoke are 90 times more likely to develop lung cancer than smokers who are not exposed to asbestos.

Diagnostic Tests

Clinical examination

History of long-term exposure to asbestos

Radiology

Interstitial markings in lower lung, thickening, plaques, calcification

Pulmonary function

Early: normal; later: reduced lung capacity and compliance

Arterial blood gases

Early: normal; later: decreased PO2, increased PCO2

Treatments

Surgery

None

Drugs

None

General

Eliminate exposure; chest physiotherapy, increased fluids, and steam inhalation to loosen secretions; oxygen therapy