The purpose of this study is to evaluate the ability of portable high efficiency particle air (HEPA) filters to reduce exposures to PM2.5 and woodsmoke air pollution indoors and to improve subclinical indicators of microvascular function, systemic inflammation, and oxidative stress among healthy adult participants.

The investigators will use portable HEPA filters in a single-blind randomized crossover design. Each participant's home will be monitored for two consecutive seven-day periods, during which time two HEPA units (one in the bedroom and one in the main living room) will be operated indoors. During one 7-day period the HEPA filters will be operated normally, and during the other period the HEPA unit will be operated without the internal filter in place (i.e., "placebo filtration"), thus blinding participants to the filters' status. The order of filtration or non-filtration will be random. At the end of each 7-day period microvascular function will be assessed, blood will be collected for assessment of systemic inflammatory markers, and urine will be collected for assessment of oxidative stress markers.

Inclusion Criteria:

• 19 years or older
• Non-smoking household
• Lives in study region (Smithers or Telkwa British Columbia)

Exclusion Criteria:

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