字幕表 動画を再生する 英語字幕をプリント Silica — it’s one of the most common substances on earth. It can be found in materials like sand and rock, and building products like concrete and brick. When a worker cuts, grinds, or drills materials that contain silica, dangerous crystalline silica dust is released into the air. As the worker breathes, silica crystals flow into his mouth and nose and down the air passages deep into the lungs. The tiny crystals enter the small fragile air sacs where oxygen is absorbed into the blood. Immune system cells called macrophages engulf and try to dissolve the crystals, but they are unable to. Over time, more and more crystals build up inside the microphage cells. The macrophages carry the silica into the walls of the lung — where they die. Scar tissue forms around the dead cells and spreads as more cells die. This damage can continue even after the exposure to silica stops. Eventually, so much scar tissue forms that the lungs can no longer function. For information on how to protect yourself from silica exposure, visit WorkSafeBC.com.