Yes, this is an appropriate medication and dosage for your symptoms. This combination of levosalbutamol and ipratropium bromide works effectively to relax and open up your airways, which directly relieves the chest heaviness and cough triggered by your dust allergy. Taking it four times daily is a standard and safe dosage to help manage acute breathing difficulties. Please ensure you use the inhalation device correctly for the best results. If your symptoms do not start to improve within a few days, or if you feel increasingly breathless, please follow up with your doctor for a review.