Hello, Allergies are known to increase in intensity overtime if exposure to the allergen continues. Smoking is also an irritant and decreases the capacity of the lung over time. If you quit smoking, it is always helpful. It not only prevents further damage to your lungs and heart but slowly they recover as well but the absolute amount of recovery depends on the amount of initial damage. In your case, in my opinion, you shouldn t link your cessation of smoking with breathlessness; it s always the opposite. Focusing back on your allergy, If I was your physician, I would like to get you examine the status of your lungs as well as test your allergies to make sure you haven t developed a new one or that the other ones are in check. It would also be advisable to start an anti-allergic like Desloratidine 10 mg daily and Montelukast sodium 10mg daily in this season, until pollen counts are below safe levels. I hope it s helpful. Thank you.