Asthalin is a SOS medications for short term relief .but for therapy inhaled corticosteroid and long acting beta 2 agonists is indicated.
Spirometry should be done
.You should avoid fumes dust smog.
Next Steps
Consult a Pulmonologist.
Health Tips
probably your dad is taking Asthalin more than is required ,thereby his tremors. He should consult a Pulmonologist who will correctly titrate the therapy. Wish you good health.