Fasting: Causing Thick Dust to Reach the Throat
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 1582
On the basis of obligatory precaution, causing thick dust to reach one’s throat invalidates a fast, whether the dust is of something lawful (ḥalāl) to eat, such as flour, or it is of something unlawful (ḥarām) to eat, such as soil.
Ruling 1583
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.
Ruling 1585
The obligatory precaution is that a fasting person must not cause the smoke of cigarettes, tobacco, or something similar to reach his throat.
Ruling 1586
If someone does not take due care and dust, smoke, or suchlike enters his throat, in the event that he was certain or confident that it would not reach his throat, his fast is valid; but if he only supposed (i.e. had ẓann) that it would not reach his throat, it is better that he keep a qaḍāʾ fast for it.
Ruling 1587
If someone forgets that he is fasting and does not take due care, or if dust or something similar reaches his throat involuntarily, his fast does not become invalid.
Ruling 1588
Immersing the entire head in water does not invalidate the fast but is highly disapproved (makrūh).