A public ASHRAE Journal podcast hosted a panel discussion where experts discuss the critical topic of protecting building occupants from smoke during wildfire and prescribed burn events. This is part two of a seven-part series.

…continued from part one.

The panel consists of:

  • Daniel Bourque, host and professional engineer from Halifax, Canada
  • Greg Nilsson, technical officer at the National Research Council of Canada. He actively researches technologies enhancing indoor air quality, with a specific focus on wildfire smoke since 2017
  • Rebecca Schmidt, a professor and molecular epidemiologist at the University of California. She studies the health effects of various exposures during pregnancy, including wildfire smoke and air quality issues
Part two of seven. Image supplied by <a href="https://www.freepik.com/free-photo/burning-shopping-center-mall-with-smoke_5430187.htm#query=burning%20building&position=6&from_view=search&track=ais&uuid=99b65f46-9549-4d21-a73f-f1af9f2d0261">Image by azerbaijan_stockers</a> on Freepik

Part two of seven.  Image by azerbaijan_stockers on Freepik

Bourque provides insight into the diverse expertise within the ASHRAE committee responsible for crafting guideline 44P. The committee comprises researchers, health professionals like Schmidt, mechanical engineers, designers, building operators and filter manufacturers. Guideline 44P has undergone several revisions, with the initial framework published in early 2022, focusing primarily on commercial buildings. The current version addresses all occupancy types, offering a general methodology and set of strategies.

The conversation shifts to the challenge of dealing with contaminated outdoor air during wildfire events. The typical approach of filtering outdoor air to reduce CO2 levels in an indoor environment becomes more complex when faced with smoke. The misconception of simply using higher MERV-rated filters is debunked, as Nilsson emphasises the importance of planning and design adaptations, whether for new constructions or existing buildings. Overloading existing systems with higher-rated filters may lead to negative pressure, pulling smoke into the building.

Guideline 44P doesn’t solely focus on filter upgrades. Instead, it offers a comprehensive set of best practices that consider planning and design strategies. For new buildings, it provides recommendations on incorporating features that enhance indoor air quality during wildfire events. For existing structures, the guideline suggests practical retrofit options to minimise smoke infiltration while avoiding negative pressure scenarios.

Applicability beyond wildfires

Bourque raises the question of whether Guideline 44P is applicable to scenarios beyond wildfires, referencing ASHRAE’s recent publications like standard 241. Nilsson clarifies that while the primary focus is on wildfires, the guidance extends to prescribed burns aimed at preventing wildfires. The guideline aims to address both wildfire events and controlled burns.

The conversation pivots to the distinctions between wildfire smoke and urban smog. Schmidt highlights differences in smoke components, with wildfires often involving vegetation fires, while urban smog includes a mix of pollutants from various sources. Despite these differences, particulate matter remains a common concern, aligning with guideline 44P’s emphasis on filtering to mitigate health risks associated with particulates.

Bourque queries the usefulness of newly established air quality stations during wildfire events. The sudden proliferation of stations in Halifax prompts a discussion on the reliability of the data. Nilsson acknowledges the well-intentioned efforts of individuals to share data but raises concerns about the potential variability and quality of sensor data, questioning its overall utility.

The guideline encourages a thoughtful, comprehensive approach to safeguarding indoor air quality during wildfire events, ensuring the well-being of building occupants. Stay tuned for further insights into this crucial guideline in subsequent podcast episodes.

Continued in part three…


Live webcast on ASHRAE website