> There is no mechanism at all I think that's somewhat misleading, the lung has a mucus layer and cilia to move particles caught in the mucus up and out. But I

> There is no mechanism at all I think that's somewhat misleading, the lung has a mucus layer and cilia to move particles caught in the mucus up and out. But I'll agree that it's not a completely robust system. Anything that gets past or can't be moved by the mucus layer is going to be a problem, especially particles that can't be broken down by the macrophages.