The study investigates the impact of HEPA air filtration on cardiovascular health during wildfire episodes. Focused on elderly individuals, it assesses the effectiveness of HEPA filters in mitigating indoor air pollution and examines its potential in reducing acute cardiovascular responses, like blood pressure and heart rate variability, during wildfires. The study’s innovative approach and real-world implications offer insights into preventative health strategies during such environmental crises.

Aim 1: To determine the effectiveness of residential HEPA filtration in reducing human exposure to PM2.5 during a wildfire event. We will use smoke dispersion models8 with satellite-based fire detections to determine the period when a residential place is influenced by wildfires. We will assess the differences in (1) indoor PM2.5 reduction during the wildfire period and (2) polycyclic aromatic hydrocarbon metabolites in urine samples (biomarkers of exposure to PM2.5) collected before and during the wildfire episode comparing participants who underwent HEPA filtration to those having sham filtration.

Aim 2: To assess the effectiveness of HEPA filtration in reducing acute cardiovascular effects (daily blood pressure, heart rate variability and atherothrombosis biomarkers) of PM2.5 during a wildfire episode. Daily blood pressure and heart rate variability will be monitored remotely using digital wearable devices. Micro-sampling of blood samples will be collected before, during and after the wildfire episode for the measurement of atherothrombosis biomarkers (IL-6, TNF-α, vWF, and MMP-9). We will examine the associations of HEPA filtration with the level of changes in cardiovascular outcomes during the wildfire episode. We will also explore whether reduced indoor PM2.5 exposure by HEPA filtration during the wildfire event mediate the effects of HEPA filtration on cardiovascular outcomes.

Impact: This supplemental study will support the urgent need to address wildfire’s adverse effects in vulnerable and susceptible populations affected by wildfire exposure. The study will provide preliminary data on the potential effectiveness of residential HEPA filtration in reducing acute cardiovascular effects of wildfire, which can inspire future studies of direct public health relevance. Furthermore, the novel exposure and digital health biomarkers to be used in the study may find wide applications in future studies.