The quality of the air in your breathing environment plays a huge role in the severity of asthma symptoms. And we’re not just talking about walking past a cigarette smoker on the sidewalk or living in a city with polluted outdoor air. Poor indoor air quality is shockingly common, says John McKeon, MD, founder and CEO of Dublin, Ireland–based Allergy Standards. The company operates the Asthma & Allergy Friendly Certification program in the United States alongside the AAFA.