Why wildfire smoke is becoming a condition engineers must plan for 

For decades, HVAC systems have been designed around semi-predictable environmental conditions: seasonal temperatures, humidity levels, and typical outdoor air quality. 

Wildfire smoke has begun to change those assumptions. 

In recent years, smoke from major wildfire events has traveled hundreds, even thousands of miles, affecting air quality across large regions of North America. Communities far from the flames are now experiencing days or even weeks where outdoor particulate levels rise dramatically. 

During major smoke events, outdoor PM2.5 concentrations can exceed 200 µg/m³ — far above levels typically assumed in HVAC design conditions. 

For building operators and engineers, this creates a new reality. 

Wildfire smoke is no longer just an environmental event reserved for certain areas of the country. It is becoming a condition that all building systems must be prepared to handle. 

When outdoor air becomes the problem 

Ventilation remains one of the most important tools for maintaining indoor air quality. Bringing outdoor air into buildings helps dilute indoor contaminants and support healthier environments for occupants. 

But wildfire smoke introduces a complication. 

During smoke events, outdoor air can carry extremely high concentrations of fine particulate matter, particularly PM2.5, which can easily infiltrate buildings through ventilation systems, openings in the building envelope, and occupant traffic. 

This creates a difficult balancing act for facility teams. The same ventilation systems designed to improve indoor air quality can become the pathway through which smoke enters the building. 

The question is no longer simply how much outdoor air to bring in. 
It is how buildings should operate when outdoor air quality suddenly deteriorates. 

HVAC systems considerations for smoke events 

Wildfire smoke is no longer an occasional anomaly for building systems. In many regions, it has become a recurring seasonal condition that engineers and facility teams must plan for. 

Instead of treating smoke events as temporary disruptions, building design increasingly needs to account for how systems will respond when outdoor air becomes the primary source of contamination. 

Designing for this reality does not mean abandoning ventilation strategies. Instead, it means considering how buildings can adapt when outdoor air quality deteriorates. This may include exploring alternative ventilation approaches, strengthening filtration strategies, and incorporating systems that allow buildings to respond dynamically to changing environmental conditions. 

This shift also aligns with the growing industry discussion around performance-based ventilation approaches, where indoor air quality outcomes are monitored and verified rather than relying solely on fixed outdoor air rates. As environmental conditions become more variable, HVAC strategies that combine ventilation, filtration, and real-time performance insight are becoming increasingly valuable. 

Approaches may include: 

• specifying filtration capable of capturing fine particulate matter 

• ensuring building systems can adjust ventilation strategies when outdoor air quality deteriorates 

• incorporating always-on indoor air quality monitoring to guide operational decisions 

• using localized air purification to support HVAC systems in occupied zones 

These strategies allow buildings to maintain healthy indoor environments while preserving ventilation and energy performance during normal conditions. 

Monitoring enables smarter responses 

One of the most challenging aspects of wildfire smoke events is how quickly conditions can change. 

Outdoor air quality can shift hour by hour as smoke plumes move across regions. Without visibility into indoor conditions, facility teams may have little insight into how those changes are affecting the building. 

Indoor air quality monitoring provides the data needed to respond more effectively. 

With real-time insight into particulate levels and other key indicators, building operators can better understand when smoke is entering the building, how indoor conditions are changing, and whether mitigation strategies are working. 

Networked monitoring platforms can help make this information accessible across a building or portfolio. For example, connected sensors can feed indoor air quality data into dashboards such as Fellowes Array Viewpoint, allowing facility teams to track trends, visualize conditions, and respond more quickly when outdoor smoke begins impacting indoor environments. 

This visibility allows operators to make informed decisions about ventilation adjustments, filtration strategies, and other operational responses during smoke events. 

Read about how two different buildings utilized monitoring through a wildfire event. 

Download the full story 

A layered approach to protecting indoor environments 

Because wildfire smoke presents a complex challenge, many buildings are adopting layered strategies to protect indoor environments. 

Rather than relying on a single intervention, effective responses typically combine several elements. 

Enhanced filtration 

Higher-efficiency HVAC filters help capture fine particulate matter before it circulates through occupied spaces. 

Localized air purification 

Targeted air cleaning systems can help reduce particulate levels in critical or high-occupancy areas. 

Operational adjustments 

Facility teams may temporarily adjust ventilation strategies when outdoor air quality deteriorates. 

Continuous monitoring 

Indoor air quality sensors provide the insight needed to guide these decisions in real time. 

When these strategies work together, buildings are better equipped to respond to rapidly changing conditions. Networked air quality solutions, such as Fellowes Array, can support this layered approach by combining localized air purification with real-time monitoring and centralized data visibility, helping facility teams understand how indoor environments are performing during smoke events. 

Layered IAQ strategies are becoming an important part of designing buildings that can respond to changing outdoor air conditions. 

For a deeper look at the system capabilities that support wildfire smoke mitigation—including monitoring, filtration, and zoned purification—download our overview below. 

Download the Wildfire Smoke IAQ System Guide 

Designing for changing environmental conditions 

Wildfire seasons are growing longer and affecting more regions each year. As a result, wildfire smoke is becoming part of a broader conversation about how buildings perform in changing environmental conditions. 

For engineers and building owners, this means thinking beyond typical operating scenarios. Building systems increasingly need to be designed with the flexibility to respond when outdoor air conditions suddenly shift. 

When smoke events are considered during the design phase, buildings are better positioned to protect indoor environments without requiring reactive measures later. 

Solutions that combine monitoring, adaptive ventilation strategies, and localized air purification can help buildings maintain healthier indoor environments even when outdoor conditions become unpredictable. 

As indoor air quality specialists, Fellowes works with engineers, facility teams, and building owners to help design layered strategies that support HVAC systems and strengthen building resilience during wildfire smoke events. Through monitoring technologies, connected dashboards, and zoned air purification systems like Array, we help provide the visibility and localized mitigation needed to support healthier indoor environments. 

Connect with us to learn more about how Fellowes can support wildfire smoke event-ready system design.