In Jain Dharma, breathing by itself is not called sinful himsa for a Tirthankar.

Why:

• A Tirthankar is still in a body until nirvāṇa, so bodily functions like breathing continue.
• In Jainism, himsa is not only the physical act; it mainly involves intention, negligence, passion, and attachment.
• A Tirthankar is free from kashāya like anger, pride, deceit, and greed. So there is no binding violence from ordinary bodily actions.
• Even though some living beings may be affected in the process of breathing, this is considered inevitable bodily activity, not sinful violence in the karmic sense for a fully enlightened being.

So the correct Jain understanding is:

Exhalation may involve unavoidable injury at the worldly level, but for a Tirthankar it does not become binding himsa because there is no attachment, no passion, and no intention.

In short: Not every bodily movement is himsa in the Jain karmic sense. Intent and inner state are crucial.