Hypothesis/Research Questions:~This study will determine whether the presence of a portable high-efficiency indoor air filter in the bedroom improves respiratory symptoms (based on St. George's Respiratory Questionnaire - COPD - SGRQ-C score) during a period of high air pollution compared with placebo in former smokers with respiratory symptoms.~The primary outcome will be the change in SGRQ-C score associated with using a portable high-efficiency indoor air filter during the study period.~Secondary outcomes will assess the effect of using a portable high-efficiency indoor air filter on healthcare utilization, other symptom scores, COPD exacerbation frequency, medication use, median daily step counts, inflammatory markers, oxygenation, indoor particulate counts and indoor-outdoor particulate count difference, and pulmonary function tests.~Baseline descriptive statistics will report baseline air filter type, duration of use, and particulate weight prior to study enrollment.~Evaluation of change in symptom scores and other secondary outcomes from baseline to study air filter (Visit 1 vs. Visit 2).
The investigators will conduct a randomized, controlled, double-blind, crossover trial to determine whether the presence of a portable high-efficiency indoor air filter in the bedroom reduces respiratory symptoms in former smokers compared with placebo. The primary outcomes will be change in St. George's Respiratory Questionnaire - COPD (SGRQ-C) score associated with using a portable high-efficiency indoor air filter during the study period. Secondary outcomes of COPD exacerbations and hospitalizations, daily step counts, medication changes, spirometry, and cardiovascular outcomes will also be assessed.