Q: I work in an iron ore mine and the nature of my work requires me to enter the mine daily. While working with mining equipment dust enters my mouth. This is my daily routine throughout the year. What is my duty? Is my fast valid?
A: Swallowing thick dust invalidates the fast by obligatory caution. Therefore, one must guard against it. However, the entering of dust into the mouth and the nose does not invalidate the fast unless it reaches the throat.