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).
