1611. Based on obligatory precaution, causing dust to reach the throat will invalidate one’s fast, regardless of whether it is the dust from legally edible (halal) products such as flour, or legally inedible products such as sand.
1612. If dust is whipped up by the wind, and a person does not take care despite being aware of it, allowing the dust to reach his throat, his fast will be invalidated based on obligatory precaution.
1613. Obligatory precaution dictates that person should not allow thick vapor, smoke from cigarettes and tobacco products, or similar items to reach his throat.
1614. If a person does not observe care, and dust, smoke, thick vapor or anything similar enters the throat, it will not harm his fast as long as he was initially certain or satisfied that it would not enter his throat. However, if he had speculated that it would not reach his throat, based on recommended precaution he should fast its qaÃÁ.
1615. If a person forgets that he is fasting, and does not exercise care, allowing dust or something similar to reach his throat, or if it reaches his throat unwillingly, his fast is not invalidated.