Do you recommend the use of portable high-efficiency particulate absolute air cleaners to former smokers with moderate to severe COPD?

This is a regional decision that is based upon ambient air pollution, such as wildfire smoke in the Southwest, and can be trialed before purchase to evaluate symptomatic efficacy. The CLEAN AIR STUDY (Hansel et al., PMID 34449285) did not validate improvement in total St George's Respiratory Questio...