Is it permissible to perform tayammum instead of ghusl for ritual impurity (janabah) due to asthma and allergies, especially in winter, and then perform wudu for prayer?

Ghusl (definition) for janabah (definition) is obligatory by consensus. If a sick person is unable to use water over their entire body, it is permissible for them to perform tayammum (definition). If they are able to wash some parts of their body but not others, they should wash what they can and perform tayammum for the rest, based on the Almighty's saying: (And if you are in a state of janabah, then purify yourselves), and based on the rule, "What is attainable does not fall away due to what is unattainable." Not every illness permits tayammum. A minor illness that does not pose a risk of harm does not justify tayammum. However, an illness that poses a risk of loss of life or limb, or delays recovery, or increases the sickness, permits tayammum. It is not permissible to delay prayer due to the inability to perform ghusl. Rather, a Muslim should pray to the best of their ability, perform tayammum if unable to perform ghusl or wudu, and pray sitting if unable to stand, based on the Almighty's saying: (Allah does not burden a soul beyond its capacity).