Effect of Portable Air Filtration Systems on Personal Exposure to Fine Particulate Matter and Blood Pressure Among Residents in a Low-Income Senior Facility: A Randomized Clinical Trial

Abstract

Importance: Fine particulate matter (smaller than 2.5 μm) (PM2.5) air pollution is a major global risk factor for cardiovascular (CV) morbidity and mortality. Few studies have tested the benefits of portable air filtration systems in urban settings in the United States.

Objective: To investigate the effectiveness of air filtration at reducing personal exposures to PM2.5 and mitigating related CV health effects among older adults in a typical US urban location.

Design, setting, and participants: This randomized, double-blind crossover intervention study was conducted from October 21, 2014, through November 4, 2016, in a low-income senior residential building in Detroit, Michigan. Forty nonsmoking older adults were enrolled, with daily CV health outcome and PM2.5 exposure measurements.

Interventions: Participants were exposed to the following three 3-day scenarios separated by 1-week washout periods: unfiltered air (sham filtration), low-efficiency (LE) high-efficiency particulate arrestance (HEPA)-type filtered air, and high-efficiency (HE) true-HEPA filtered air using filtration systems in their bedroom and living room.

Main outcomes and measures: The primary outcome was brachial blood pressure (BP). Secondary outcomes included aortic hemodynamics, pulse-wave velocity, and heart rate variability. Exposures to PM2.5 were measured in the participants' residences and by personal monitoring.

Results: The 40 participants had a mean (SD) age of 67 (8) years (62% men). Personal PM2.5 exposures were significantly reduced by air filtration from a mean (SD) of 15.5 (10.9) μg/m3 with sham filtration to 10.9 (7.4) μg/m3 with LE fitration and 7.4 (3.3) μg/m3 with HE filtration. Compared with sham filtration, any filtration for 3 days decreased brachial systolic and diastolic BP by 3.2 mm Hg (95% CI, -6.1 to -0.2 mm Hg) and 1.5 mm Hg (95% CI, -3.3 to 0.2 mm Hg), respectively. A continuous decrease occurred in systolic and diastolic BP during the 3-day period of LE filtration, with a mean of 3.4 mm Hg (95% CI, -6.8 to -0.1 mm Hg) and 2.2 mm Hg (95% CI, -4.2 to -0.3 mm Hg), respectively. For HE filtration, systolic and diastolic BP decreased by 2.9 mm Hg (95% CI, -6.2 to 0.5 mm Hg) and 0.8 mm Hg (95% CI, -2.8 to 1.2 mm Hg), respectively. Most secondary outcomes were not significantly improved.

Conclusions and relevance: Results of this study showed that short-term use of portable air filtration systems reduced personal PM2.5 exposures and systolic BP among older adults living in a typical US urban location. The use of these relatively inexpensive systems is potentially cardioprotective against PM2.5 exposures and warrants further research.

Trial registration: ClinicalTrials.gov identifier: NCT03334565.

Conflict of interest statement

Conflict of Interest Disclosures: Dr Brook reported receiving an investigator-initiated research grant from RB, Inc. No other disclosures were reported.

Figures

Figure 1.. CONSORT Diagram

BP indicates blood pressure.

Figure 2.. Changes in Brachial Blood Pressure (BP) Levels

A, BP levels represent overall changes during all days of any filtration type compared with the 3-day sham filtration. B, BP levels represent individual daily and 3-day mean changes during each separate filtration type compared with the corresponding sham filtration day. C, BP levels represent overall changes during all days of any filtration type compared with the 3-day sham filtration among all, 19 obese (body mass index [calculated as weight in kilograms divided by height in meters squared]≥30), and 21 nonobese participants. Error bars indicate 95% CIs; Δ, difference. DBP indicates diastolic BP; HE, high-efficiency; LE, low-efficiency; and SBP, systolic BP. aP < .05, test of fixed effects from the adjusted mixed model.

Figure 3.. Change in Secondary Outcomes (Aortic Hemodynamics) by Filtration Type During Each 3-Day Intervention

Results represent individual daily and 3-day mean changes during each separate filtration intervention type compared with the sham filtration. Augmentation and pulse pressures are measured for the aorta. Error bars indicate 95% CI; Δ, difference. AIx@75 indicates augmentation index standardized to a heart rate of 75 beats/min; HE, high-efficiency; LE, low-efficiency; and PWV, pulse-wave velocity. aP < .05, test of fixed effects from the adjusted mixed model.