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BS* + Beer

Fire-Related Indoor Air Quality

Experts discuss the increasing problem of unhealthy indoor air quality that follows a wildfire event and what to do about it

Increasingly wildfires are leveling houses but even houses that survive the flames may harbor hidden health risks for their returning owners. Photo courtesy Al_HikesAZ CC BY-NC / Flickr.

This episode of the BS* + Beer Show features John Semmelhack, Gail Carlson, and Blake Reid talking about Indoor Air Quality in the Age of Wildfires. There are few regions in the country that are not increasingly affected by wildfire smoke, and the building industry is being forced to respond accordingly. This group of experts discusses the human health consequences of air pollution exposure, outdoor air filtration (MERV and HEPA) and their limitations, factors that impact indoor particulates (and concerns beyond particulates), the effectiveness of spot ventilation, why PM2.5 is the threshold, and much more.

Enjoy the show!


John Semmelhack is the owner of The Comfort Squad. He is a Certified Passive House Consultant, a member of the Passive House Institute U.S. (PHIUS) Technical Committee, and a PHIUS Trainer for the Certified Passive House Consultant and PHIUS+ Rater training programs. He sits on the boards of the Passive House Alliance U.S. (PHAUS) and the Passive House Alliance U.S. – Capital Chapter. John is also a certified Home Energy Rating System (HERS) rater, a Technical Advisor to builders in the EarthCraft House Virginia green building program, and a BPI-certified Building Analyst. He is a graduate of the Leeds School of Business (no, not that “LEED”) at the University of Colorado at Boulder.

Gail Carlson is biochemist and an environmental studies professor at Colby College. She focuses on the ways in which the environment impacts human health via climate change, extractive and polluting industrial activities, and exposures to hazardous chemicals. She works with students on advocacy campaigns in Maine to raise awareness about these issues and to advance support for legislative initiatives. Her research focuses on the role of state policymaking in advancing innovations to improve environmental health.

Blake Reid is owner of Terrawatt, specializing in insulation and air-sealing work for low-carbon homes in Waimea, Waikoloa, Kailua-Kona, Hilo, the Big Island, and the islands of Hawaii.

The BS* + Beer Show schedule

The next show is on October 5, 2023, from 6-7 p.m. ET.

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  1. finePNW | | #1

    Oh man, this is a lovely episode. As an air pollution scientist specializing in particulate matter and wildfires, it's a big reason I'm going all-in on air sealing our home. Thanks for putting this show together!

    1. Deleted | | #2


  2. finePNW | | #3

    Love the discussion around Corsi/Rosenthal Box Air Cleaner! A new study shows that while this can cover a room size ~ 70% larger than a single filter box fan, it also also requires more filters which in a place like Maui may be substantially more expensive than simply making two single-filter box fans. ( Either way, much better than nothing!

    One thing I think needs attention in the public sphere is guidelines around replacing the filters in a Corsi/Rosenthal Box (or other box-fan air filter unit). I'd love to hear some data-driven discourse around that.

    I really liked the discussion of ERV + filter box, as I'm looking into this myself. As I understand it, filtration efficiency is a function of air velocity (flow rate). Do you know if the MERV16 filter you use operates at it's fully rated efficiency under the flow rates it sees in your ERV system?

  3. Expert Member
    Michael Maines | | #4

    Thanks for the write-up, Kiley! Our next show will be on October 5, with Nikki Krueger talking about dehumidification. And on November 2, Gary Klein will be on to talk about hot water distribution.

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