The progression of asbestosis is supposed to begin with the first order of respiratory bronchiole and extend outward. Recently, grade 4 asbestosis was reported to begin with the subpleural peripheral lobular area or the subpleural lobule. Grade 4 asbestosis is defined as diffuse pulmonary fibrosis caused by the inhalation of excessive numbers of asbestos fibers. Pathologically, the presence of more than two asbestos bodies/cm2 on a glass slide is required. There are many cases of diffuse interstitial pneumonia, mainly usual interstitial pneumonia, that does not fulfill the above criteria among asbestos workers or high-grade environmentally exposed persons. I call these cases “usual interstitial pneumonia seen in asbestos workers” and not idiopathic pulmonary fibrosis. In this chapter, I discuss the above subjects, including the dose-response relationship for asbestos exposure, the heterogeneous response to asbestos exposure, and the relationship between asbestosis and idiopathic pulmonary fibrosis.
Part of the book: Asbestos-related Diseases