Wildfire Smoke and the Indoor Air Quality Monitoring Gap

Shawn Gilstorf, Vice President, Rensa Filtration

By every measure that shows up on a dashboard, many buildings look like they’re performing well. The particulate filters many facilities  upgraded are doing what they are designed to do. Particle readings from indoor-air-quality monitors may show improved  performance, giving facility teams confidence that their buildings are protected. The particle readings that many air-quality monitors track may sit comfortably in the green.

Then a wildfire plume drifts through the region, and the lobby starts smelling  like a bonfire. Employees ask why the air feels off when the dashboard still shows green.

That gap between what a building’s monitoring system reports and what occupants may actually experience is a blind spot for EHS and sustainability leaders. And it comes down to a simple fact about smoke: It’s made up of far more than soot and ash.

The truth is that wildfire smoke is  a complex chemical mixture. Alongside the visible particles, it carries a load of invisible gases like formaldehyde and benzene—the same kinds of hazardous compounds found in vehicle exhaust and industrial emissions.

These gaseous pollutants can contribute to the smoke odor, eye irritation, headaches, and air-quality complaints that occupants report even when particulate readings look fine. They raise health concerns that may not be reflected in a building’s conventional particulate measurements, because traditional mechanical filtration is primarily designed to capture particles rather than gaseous contaminants.

Unfortunately, low particulate readings do not equal low health risk during a smoke event, and this discrepancy can leave occupants exposed.

The Transparency Gap Left by Current Strategies

Part of the vulnerability is historical. Most commercial HVAC systems were designed around urban pollution, seasonal allergens and ordinary outdoor air, not prolonged wildfire smoke intrusion. The assumptions that reassure facility teams tend to break down under smoke conditions.

Those gases are hard to detect, rarely monitored around the clock, and largely absent from the sustainability reports leaders depend on.

And the exposure is no longer a local issue.

In 2023, smoke from Canadian wildfires drifted across large stretches of the U.S. Northeast and Midwest, fouling the air hundreds of miles from any flames. It even reached buildings whose operators never imagined they were anywhere near a fire zone.  According to the EPA, wildfire smoke can  travel  thousands of miles, increasing the extent of the population exposed to smoke health risks.

The Tradeoff Leaders Need to Face Now

This is where the problem gets genuinely complex and nuanced. Protecting people during a smoke event usually means more filtration and more air treatment.

This is where the problem gets genuinely complex. Protecting people against smoke may require additional filtration or air treatment, but filtration also affects airflow resistance. Higher pressure drops can increase the work required from fans, adding energy use and increasing operational costs. For organizations with aggressive energy, emissions and carbon targets, those impacts cannot be treated as an afterthought. 

The solution therefore is not to simply add more filtration. A comprehensive approach should include filtration media, system configuration, airflow requirements and pressure drop together. Gas-phase filtration can be incorporated into a broader smoke -resilience strategy, but its energy impact depends on how the system is designed and operated.

The result is a set of competing pressures landing on a single team.

Framed as an “either/or” proposition, occupant health and carbon goals appear to be in conflict. A more useful approach is to treat wildfire resilience as a part of an organization’s broader sustainability and energy resilience strategy, which can be designed proactively rather than added reactively when smoke arrives.

A Better Way Forward Is Emerging

That is the shift a new industry framework is built to support. Published in 2024, ASHRAE Guideline 44-2024, Protecting Building Occupants from Smoke During Wildfire and Prescribed Burn Events is designed to help building owners and operators get ahead of smoke events.

It lays out a structured playbook that covers Smoke Readiness Plans, building sealing, air sensing, filtration, and day-of operations for commercial, healthcare, institutional and residential buildings.

Its foundation is particle control, but it goes a step further by directing teams to consider whether their systems can also handle gas-adsorbing filtration as part of a smoke plan. It’s a clear and timely acknowledgment that particles are only half the problem. And it captures the mental shift leaders can make now: from merely filtering the particles to addressing everything in the smoke

In practice, fuller protection does two jobs at once: It captures the particles, and it adsorbs the gases the particle filters miss, usually with activated carbon which is the same material that purifies a water pitcher.

Handled as a unified designed system rather than an afterthought, that combination protects offices, hospitals, campuses, plants and data centers alike. And because the energy cost of gas filtration depends largely on how it is engineered, the tradeoff can be proactively planned for rather than addressed reactively during a smoke event.

Gas-phase filtration commonly relies on activated carbon or other materials designed to capture gaseous contaminants. Performance depends on factors such as material selection, contaminant concentration, airflow, contract time, pressure drop and system configuration. Evaluating those variables together can help organizations balance contaminant removal with energy and operating requirements of their HVAC system.

Five Focus Areas for the Next Smoke Event

For any organization, there are key areas that require attention to ensure preparedness.

1. Risk: Is wildfire smoke part of our enterprise risk planning, and are our facilities in direct or indirect smoke pathways?
2. Monitoring: What are we measuring today, and what are we missing? Does our monitoring strategy address particulate matter only, or does it also account for relevant gaseous contaminants?
3. Readiness: How long can each building maintain acceptable indoor conditions during prolonged smoke events and which spaces are most vulnerable?
4. Sustainability alignment: Are we weighing our resilience investments against our ESG goals? And are we measuring energy impact alongside health outcomes?
5. Governance: Who owns wildfire preparedness? Is it EHS, sustainability, facilities or risk management?

For many organizations, the answer to that last question is “No one, exactly.” And it’s that precise ambiguity of ownership that lets the smoke in.

Building the Next Generation of Resilience

Wildfire smoke used to be a seasonal surprise, but it’s becoming a recurring operating condition. The organizations that handle it best will be the ones that stop treating clean particle counts as the finish line. They will look beyond particulate measurement, incorporate relevant gas-phase considerations into their smoke-readiness planning, and use guidance such as Guideline 44 to connect occupant protection with energy and sustainability objectives.

The most resilient buildings will be those that can maintain healthy indoor conditions while continuing to meet their operational and sustainability goals. Preparing for wildfire smoke is therefore not a choice between occupant protection and energy performance. With the right planning, monitoring and filtration strategy, organizations can address both.

Shawn Gilstorf currently serves as the vice president of product management at Rensa Filtration and air filtration specialist and the former  President of D-Mark (a Rensa Filtration company). He has spent more than two decades designing and developing gas-phase, molecular, and biological safety filtration solutions for critical environments across the medical, industrial, and commercial sectors.