Why isn’t the puffer for asthma regarded as breaking the fast?

I would like a detailed answer: why isn't the puffer that is used by
people who have asthma regarded as breaking the fast?.
Praise be to Allaah.
The puffer is a container in which there is a liquid medicine composed
of three things: chemical substances (medical preparation), water and
oxygen.
When pressure is applied to the puffer, the medicine comes out in
theform of a mist. If the patient takes a deep breath in when applying
pressure to the puffer, thismist enters the airway (trachea), but some
of it remains in the pharynx, and a very small amount of it may enter
the oesophagus.
Some contemporary scholars are of the view that using a puffer
invalidates the fast. They said: Because the contentsof the puffer may
reach the stomach via the mouth, so it breaks the fast.
But most contemporary scholars are of the view that using this puffer
doesnot break the fast, and this view is the correct one. They quoted
a number of things as evidence for this:
1.
The basic principle is that the fast remains valid, andthis fact
cannot be alteredexcept when there is certain proof. Whether part of
the mist from the puffer reaches the stomach is something uncertain:
it may enter the stomach or it may not, because the basic principle is
that this substance goes to the respiratory system, but some of it may
enter the stomach. With this uncertainty we cannot saythat it
invalidates the fast.This is the answer to the evidence for the first
opinion.
2.
Assuming that some of this medicine does actually enter the stomach,
it is forgiven, and does not invalidate the fast, by analogy with
rinsing the mouth and using the miswaak.
With regard to rinsing themouth: when the fasting person rinses his
mouth, some of that water remains in his mouth, andsome of that water
may go down to the stomach. Hence if he rinses his mouth with water in
which there is a radioactive substance, that radioactive substancewill
appear in his stomachafter a while, which confirms that some of the
water used for rinsing themouth does go down intothe stomach. But this
part that goes down into the stomach is a very small amount, which is
overlooked in sharee'ah. The ruling is that the fast is still valid if
one rinses the mouth. The amount ofmedicine from a puffer that reaches
the stomach – if any – is smaller than the amount of water that
reaches the stomach when one rinses the mouth, so it is more
likelythat it does not break the fast.
As for the siwaak, it contains a substance that dissolves in the
saliva andgoes down into the pharynx, and then to the stomach. But
Islam overlooks this, and does not regard it as invalidating the fast,
because it is a small amount and is not intentional. Similarly the
part that may go down into the stomach from thepuffer is small, and
the patient does not intend for it to enter the stomach, so it does
not break the fast, by analogywith the miswaak.
Thus the strength of the second view is apparent. This is the view
favoured by our contemporary scholars: Shaykh 'Abd al-'Azeez ibn Baaz
(may Allaah have mercy on him), Shaykh Muhammad ibn al-'Uthaymeen,
Shaykh 'Abd-Allaah ibn Jibreen, and the scholars of the Standing
Committee. We have quoted some of their fatwas concerning this in the
answer to question no. 37650 .
See: Majallat al-Fiqh al-Islami (vol. 10, in whichthere are a number
of articles about modern things that break the fast); Muftiraat
al-Siyaam al-Mu'aasirah, by Dr. Ahmad al-Khaleel, p. 33-38.