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Using a particle sensor network to characterize indoor and outdoor air quality of buildings in areas prone to wildfires
Citation:
Vreeland, H., A. Holder, S. Coefield, B. Schmidt, G. Neal, E. Weiler, C. Noonan, B. McCaughey, AND G. Hagler. Using a particle sensor network to characterize indoor and outdoor air quality of buildings in areas prone to wildfires. The 3rd International Smoke Symposium, Virtual meeting, Virtual Meeting, April 21 - 22, 2020.
Impact/Purpose:
The purpose of this work is to evaluate how effectively buildings can reduce outdoor air pollution to safe levels indoors. This work demonstrates the utility of using low-cost sensor networks to evaluate real-world conditions (including opportunistic measurements of smoke events) in indoor spaces relevant to daily human exposures (i.e., in places where people spend a lot of time, such as office spaces, schools, and community centers). In this study low cost PM sensors were used to measured indoor and outdoor particulate matter concentrations in 17 building across Missoula Montana and 11 building across Hoopa California. Buildings with a central heating ventilation and air conditioning system had low particulate matter concentrations compared to those without. However, buildings with similar filtration systems exhibited diverse indoor air quality showing the impact building use.
Description:
In areas of the United States where wildland fires are a frequent occurrence, exposures to fine particulate matter (“PM2.5” or particles with aerodynamic diameters smaller than 2.5 micrometers) from smoke emissions are an increasing cause for concern. To reduce pollutant exposures, it is often recommended to spend more time in clean indoor spaces. However, many northern regions affected by wildland fire smoke lack air conditioning systems and rely on open window ventilation for cooling during summer months that coincide with peak fire season. Additionally, buildings with high foot traffic (e.g., fitness centers, museums, community centers) may have recurrent door openings that increase infiltration from outdoor air. To gain insight on the effectiveness of using indoor spaces to mitigate air pollution exposures, this study characterizes indoor and outdoor PM2.5 concentrations at a variety of commercial and community buildings that were anticipated to have high indoor occupancy during wildland fire smoke events. During summer 2019 (July–September), 18 buildings in Missoula, Montana were monitored continuously using low-cost particle sensors (PurpleAir PA-II-SD) that report estimated PM2.5 concentrations every 2 minutes. Each building facility provided relevant operational factors including door/window openings, use of air handling systems, portable air cleaners, and filter maintenance. Unsurprisingly, buildings that lacked central air/HVAC filtration systems showed no reduction in PM2.5 concentrations indoors. Buildings that utilized HVAC systems – even at the same filter rating – showed widely varying impacts on indoor air quality. This work also compares a second sampling site, which assessed indoor and outdoor air quality of 11 buildings in Hoopa Valley, California during the wintertime (Nov 2019 – Feb 2020) when outdoor air was impacted by daily smoke emissions from residential woodstove heating. Although the only wildland fire smoke events that occurred in Missoula during summer 2019 were moderate and associated with prescribed burns, this work provides valuable insight into the variance among outdoor/indoor air quality conditions and the strategy of using emerging air sensor technologies to collect a very large data set to characterize dynamic PM2.5 conditions. The views expressed in this abstract are those of the authors and do not necessarily represent the views or policies of the U.S. Environmental Protection Agency.