HEPA, PM2.5, and Cardiometabolic Health

Inclusion Criteria: * Age between 65 and 84 years old; * Nonsmoker for at least 1 year; * History of BMI ≥ 25 kg/m2 in the past based on EMR information; * Either an English or Spanish speaker; * Live in the Los Angeles County. Exclusion Criteria: * History of diabetes (both type 1 and type 2) or degenerative disease of the nervous system (Alzheimer's disease or dementia); * Currently have active cancer treatment; * The residential house has already had HEPA filters; * Participants will move out of the current house in the next 2 years; * Participants will spend more than one month living outside the primary home; * Have any health conditions that prohibit collecting health and covariate data and biospecimen; * The residential houses are not feasible for setting up air purifiers and air pollutants monitors; * Have high blood glucose from finger stick test (\> 200 mg/dL).