Impacts of Professional Cleaning Activities on Indoor Particulate Matter Following a Wildfire Event

Avery Hatch, LIORA MAEL, Marina Vance, University of Colorado Boulder

     Abstract Number: 104
     Working Group: Indoor Aerosols

Abstract
Wildfire events have increased in length and severity over the years, contributing significant amounts of particulate matter (PM) pollution outdoors and to indoor environments. While guidelines encourage people to remain in their homes during wildfire events, wildfire PM can infiltrate homes, affecting indoor air quality, and potentially causing visible soot and ash deposition within living areas. There is a pressing need to understand how post-fire cleaning efforts can affect PM levels in a home. Following the significant Marshall Fire wildfire event in Colorado in January 2022, this study assessed size-resolved PM concentrations in an unoccupied single-family home that had been evacuated and impacted by wildfire smoke, but not structurally damaged. We monitored aerosol size distributions using a scanning mobility particle sizer and an aerodynamic particle sizer before, during, and after professional cleaning activities were conducted in this home. Results show that (1) PM_2.5 concentrations remained relatively low throughout the duration of the study, (2) cleaning activities caused spikes in indoor PM₁₀ and PM_2.5 concentrations, (3) the operation of the home mechanical ventilation system led to new particle formation events and those particles remained in the ultrafine mode. These findings suggest that indoor PM levels are affected by post-fire mitigation actions, and that if cleaning activities are undertaken by household occupants or professionals, safety precautions should be considered and personal protective equipment would be recommended.