Home Air Filtration for Traffic-Related Air Pollution: Study Design and Methods

Abstract

Despite reducing indoor particulate matter (PM) pollution from traffic, it is not established that freestanding air filters in homes benefits cardiovascular health. We are launching a randomized crossover efficacy trial of high efficiency particulate arrestance (HEPA) filters in homes near a highway in Somerville, MA, USA. The approach is community-engaged research with active participation of community partners. Drawing on lessons from our pilot studies, we will focus on colder seasons when windows are less likely to be open and exclude participants with serious health problems or use of antihypertensive or anti-inflammatory medications. Over 3.5 years we will recruit 210 homes with 240 study participants aged 40-75. Each home will receive, in random order, two HEPA units either with or without (sham) filters for one month. Following a one-month wash out period, the filtration condition will be reversed. We will exclude smoking households and people who work at jobs with significant PM exposure. At baseline and at one-month intervals we will interview each participant for demographics, relevant behaviors and health symptoms. Blood pressure (central and peripheral) and blood draws taken at monthly intervals will be the primary health outcomes. Blood samples will be stored at -80 ᵒC and analyzed for inflammatory (IL-6) and coagulation (D-dimer) biomarkers. Secondary outcomes will be metabolome, asthma, allergy and cognitive function. We will monitor particle number concentration, PM2.5, PM size distribution and composition in a subset of homes for one week each during filtration and sham. Time activity will be self-reported monthly and we will measure time spent in the rooms with filters for a subset using custom Bluetooth technology. The results will provide evidence for or against use of air filters in homes to reduce health effects of traffic-related PM. We will investigate participant experience and reasons for compliance via interviews.