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 four of a seven-part series.

…continued from part three.

Part four of seven. <a href="https://www.freepik.com/free-vector/firefighters-cartoon-composition-with-outdoor-fire-illustration_14260781.htm#query=fire%20in%20building&position=9&from_view=search&track=ais&uuid=3cedc77c-984d-4297-8769-3b2db348899f">Image supplied by macrovector</a> on Freepik

Part four of seven. Image supplied by macrovector on Freepik

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

Bourque reflects on particulate matter as a surrogate measure for the various components present in wildfire smoke. He acknowledges the complexity of smoke, consisting of around 5 000 different components. However, particulate matter serves as a convenient and measurable standard, representing the overall mix of harmful constituents. Schmidt concurs, highlighting the correlation among different components in smoke and the ease of measuring particulate matter as a representative indicator.

Nilsson elaborates on the misconceptions surrounding smoke particles, emphasising that they’re not necessarily solid like sand but can encompass semi-volatile organic compounds (VOCs) in small droplets. The measurement process involves lasers detecting particles as they pass through, providing a generic sense of their size. Nilsson explains that the composition of smoke particles can change based on factors such as temperature and sunlight exposure, making smoke a dynamic and photochemical substance.

Schmidt contributes insights into the unique characteristics of wildfire smoke, drawing parallels with smog due to its photochemical nature. She introduces the concept of aging, where smoke undergoes changes as it travels, resulting in peaks in ozone and the presence of substances like formaldehyde. Toxicology studies comparing urban wildfires to vegetation fires reveal greater toxicity in the smoke from urban wildfires, emphasising the need for effective filtration.

Prescribed burns and smoke composition

Bourque shifts the conversation to prescribed burns and the composition of smoke generated during these intentional burns. He dismisses the notion of one type of smoke being ‘better’ than another based on the source, emphasising that the goal is to minimise exposure to smoke in all cases. The discussion reinforces the overarching principle that, regardless of the source or composition, smoke poses health risks that need to be addressed.

Continued in part five…


Live webcast on ASHRAE website