Causing dust that is not thick to reach the throat does not invalidate a fast. Ruling 1584.* If thick dust appears and a person – despite being aware and able to take care – does not take care and the dust reaches his throat, then based on obligatory precaution, his fast becomes invalid. However, if dust were to appear by means of the wind or a storm and suchlike, and preventing it from reaching one’s throat would be considered excessively difficult, then preventing it would not be necessary.