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How can silicosis continue to worsen after a worker stops breathing silica dust?

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Asbestosis — occupational disease The lung disease asbestosis is caused primarily by prolonged inhalation of asbestos fibers. It occurs mainly among workers whose occupations involve exposure to asbestos and people who live near mines, factories, and construction sites.

Silicosis can continue to worsen even after a worker is no longer exposed to silica dust because the disease is driven by a persistent, self-perpetuating cycle of tissue damage within the lungs.1

When silica particles are inhaled, they are ingested by scavenger cells known as macrophages, which are intended to protect the body. However, because silica cannot be digested or broken down by these cells, the particles eventually kill the macrophages. As these cells die, they release their contents and trigger the formation of nodules of fibrosis—dense, fibrous tissue.231

This process creates a chronic inflammatory response where the body continues to recruit more immune cells to the site of the injury. The resulting fibrotic masses gradually enlarge and contract, which distorts and further damages the lung structure. Because the silica particles remain trapped in the lung tissue and cannot be removed by the body’s natural defenses, this cycle of inflammation and scarring can progress for years, leading to increasing disability long after the initial exposure has ceased.321