A dusty, dry chicken is a happy chicken. Notably, the concept of dust-bathing, but also the dander they constantly produce which can lead to silicosis in humans where there is overexposure.
While poultry tend to be susceptible to fungal infections of the respiratory tract, dry dust does not seem to cause any adverse effects in them; one could even assume that one of the functions of silicate dust is to absorb moisture and in doing so, prevent spores from germinating internally.
But how is it that chickens' respiratory tracts can handle this quantity of dry dust, as compared with humans and other animals which would be adversely affected? How do they stay moist and lubricated inside, and allow clear surfaces for gas exchange within the lungs?