A randomized crossover trial of portable in-home air purifiers for highway PM and cardiovascular risk: HAFTRAP study update

Abstract

Background and aim: We have shown previously that cardiovascular biomarkers are associated with traffic-related air pollution (TRAP) near highways and that reducing particulate exposure improves blood pressure (BP) in controlled settings. Our aim here is to assess the efficacy of portable in-home high-efficiency particle arrestance (HEPA) air purifiers to reduce indoor concentrations of TRAP and therefore reduce BP and systemic inflammation in a real world, lived-in setting. Methods: We are conducting a randomized crossover trial of air purifiers in homes <200m from a major highway. Participants receive real or sham filtration for one month each separated by a one-month wash out period. We collect peripheral and central BP, as well as blood samples for inflammatory biomarker analysis before and after each one-month period. We also conduct air monitoring and satisfaction interviews with a subset of homes and participants. Results: A sample of 57 participants has been enrolled with recruitment ongoing. Thirty-three percent live within 100m of the highway. The average age of participants is 44 years (range: 30-78 years), 68% are female, and 37% are racial/ethnic minorities. The mean (SD) baseline peripheral and central systolic BP are 123 (14) mmHg and 113 (13) mmHg, respectively. Indoor and outdoor PNC measurements indicate that median concentrations were 40-60% lower during HEPA than SHAM and during HEPA use indoor concentrations were 60-70% lower than outdoors. Data on electricity use and quantitative and qualitative feedback suggest air purifiers were on the medium setting most of the time. Conclusions: Approximately one-third of the way to our recruitment goal we have good acceptance and compliance with the intervention, quality data and indications that the air purifiers are reducing TRAP as intended. An interim analysis of health outcomes should be possible in a year.