Why Cleaner Air is the Next Frontier for Plant Reliability

Introduction: The Invisible Contaminant

At this year’s Reliable Plant conference, much of the discussion centered on lubricants. That makes sense: lubrication, vibration analysis, and thermal monitoring have long been pillars of reliability programs. But one area that received far less attention, despite its impact on performance and cost, is air quality.

In many plants, HVAC systems typically both pull in fresh outdoor air and recirculate indoor air from processes. Dust, soot, fumes, lint, and mist move constantly through equipment and filters. Left unmanaged, they clog systems, reduce efficiency, and drive up operating costs.

And here’s the catch: filters alone don’t guarantee clean air. Without monitoring, it’s very difficult to know how many contaminants are present, how quickly filters are loading, or whether systems are keeping up. Monitoring is what transforms filtration from a routine expense into a reliability tool. But how many plants perform it? 

Photo 1: Typical manufacturing plant with machinery, workers and inventory

Why Air Quality Matters

1. Hidden failure modes. Dust and particulates settle on exposed bearings, motors, and electronics, creating thermal stress and premature failure. Oil mist migrates beyond lubrication zones, coating sensors and controls. Welding and ultra fine machining particulates can clog HVAC coils, degrading airflow and driving up maintenance costs.
2. Energy impact. Clogged filters force HVAC fans to either work harder or run longer to maintain airflow and temperature setpoints. In both cases, energy consumption rises, and fan energy use alone can increase significantly. When contaminated air is vented outdoors, plants must also condition large volumes of “make-up” air, adding significant utility costs.
3. Risk exposure. Many facilities underestimate or overlook the impact of indoor air quality on equipment reliability and the work environment. OSHA case data show inadequate ventilation is the root cause in ~52% of indoor-air investigations, something plants can address through monitoring, filtration and ventilation management (source).

The Trap of Visual Inspections

Many facilities still rely on visual inspections or fixed schedules to decide when to change filters. Both approaches are flawed. 

• A filter that looks dirty may still have capacity and thus changing is a waste of time and money. 
• Conversely, a filter that looks clean may already be loaded with ultrafine particles, restricting airflow and forcing the system to operate beyond design limits. 

This “looks can be deceiving” problem is widespread.

Photo 2: Filters from different environments. Which filter is clogged the most?

Everyday Examples

Air quality challenges aren’t unique to plants, they show up in our homes too.

• Cooking, candles, and smog. Everyday activities like frying food or burning candles produce fine black particles that quickly make a filter appear dirty. If you live near a busy street, smog can seep indoors and have the same effect. In many cases, the visible dust is just a thin surface layer and airflow through the filter media may still be largely unaffected.
• Humidifiers and diffusers. Ultrasonic humidifiers are often used when kids are sick, but when filled with tap water they release dissolved minerals as a fine white powder. These can clog a filter in a short time even when the filter still looks new to the eye. 

Industrial Parallels

The same misleading appearances occur in manufacturing:

• Welding and high heat processes generate black soot-like particles that can discolor a filter rapidly, giving the impression it’s “used up,” even though airflow may still be strong.
• Cutting, grinding, and machining can create ultra fine particulate matter that loads filters internally without dramatic surface change.
• Spray applications and misting operations, especially when spraying with untreated water which may contain minerals, for example calcium which is white so it looks clean.
• Bulk handling of powders, textiles, or plastics releases fine particulates that accumulate deep within filter media.

The lesson: appearance is deceptive. Condition-based monitoring is the only way to know the difference. 

Filter Life is Variable

Another misconception is that filters have a predictable lifespan. In reality, conditions determine filter life and it can vary widely: sometimes lasting a year, other times clogging in just weeks or even days.

Factors that shorten filter life include:

• High dust loads and ultrafine particulate matter (for example, from sanding or textile operations).
• Emissions from welding, grinding, or machining.
• Environmental events like smoke, soot, or construction dust.
• Humidification using ultrasound to atomize water with minerals

Fixed schedules very often miss the mark:

• Too early: Wastes money on materials and labor.
• Too late: Increases energy costs, reduces airflow, and risks equipment damage.

A Smarter Approach: Condition-Based Filtration

Advances in monitoring now allow filters to be managed with the same rigor as oil analysis or vibration tracking. 

• Air quality monitoring. Deploying sensors across a facility creates a “mesh” of visibility. Spikes in particulate levels can help reveal sources such as welding bays, grinding areas, or chemical processes. However, sensor drift, calibration error, and environmental crossinterferences must be managed (e.g. via periodic collocation or recalibration). Using lower-cost sensors can also exacerbate such problems, since these have been shown to be more prone to drift, sensitivity loss and bias over time.
• Differential pressure monitoring. Measures the resistance a filter creates against airflow, indicating exactly when it needs replacement.
• Smart or active filtration. In facilities with sections controlled by dedicated HVAC systems and smart thermostats, air quality monitors can be integrated so that circulation is automatically triggered when particulate levels rise.
• Integration with reliability programs. Air health data can be logged in CMMS systems, making air another component of condition-based maintenance.

Case Studies and Lessons

Real-world examples highlight how measurement changes outcomes. 

Quick-Serve Restaurants: Rooftop Unit Efficiency Case Study
Monitoring rooftop HVAC units revealed most filters could safely last 4x longer or more, while a few needed fan belts adjusted/fixed or coil freezes were investigated. By adjusting changes to actual conditions, operators reduced waste, cut fan energy consumption, and minimized rooftop maintenance calls. 

Hospitality: Guest Comfort and Reliability Case Study
At an 150 room extended-stay hotel, measurement showed that three-quarters of guest-room filters lasted a full year, while others needed replacement sooner. Aligning changes to real performance reduced labor and material use by $10,251/annually, prevented HVAC outages, complaints, and improved guest satisfaction.

Laundromats: Lint and Labor Reduction Case Study
Laundry operations often replace filters weekly because they look dirty. Data showed airflow remained strong far longer. Extending filter life cut filter changes by 65%, reduced costs by 48%, and prevented collapsed filters that once contaminated coils.

What’s Next: Manufacturing Applications
At a food processing facility where multi-stage filtration is required, monitors paired with filter selection suggest maintenance costs could be reduced by up to 50% without compromising compliance.

Things to Consider

Every facility is different, and there isn’t a one-size-fits-all approach. But there are several factors worth considering:

1. Establishing a baseline. Air quality monitors can be deployed throughout a facility to track particulate levels in different areas. This helps identify zones where filtration is most needed.
2. Filter selection. Many HVAC technicians use MERV 8 as a baseline. Where no secondary filtration exists, upgrading to MERV 11 or MERV 13 may offer better protection—but the tradeoffs (higher pressure drop, fan capacity, cost) must be evaluated.
3. Integration with existing practices. Air quality and filtration data can complement vibration analysis, thermal imaging, or oil analysis.
4. Continuous improvement. Reviewing data trends over time helps refine practices, guide filter selection, and avoid surprises.

Challenges and Considerations

Implementing air quality monitoring and condition-based filtration does require some upfront investment, both in sensors and in training teams to interpret the data. ROI often comes quickly, thanks to scenarios where we see energy savings and fewer filter replacements. The key is to focus on identifying practical requirements and actionable thresholds rather than overwhelming maintenance staff. 

Clean Air as a Reliability Tool

Anyone in reliability already knows the importance of contamination control. It’s the same principle that keeps lubricants clean and machines running smoothly. Air is no different. Cleaner air reduces strain on HVAC systems, prevents particulates from coating coils and electronics, and helps keep processes running at peak efficiency.

But there’s a common blind spot: many facilities assume that simply having filters in place means air quality is under control. In reality, filters are only half the story. Without monitoring, you can’t see how quickly filters are loading, whether they’re clogging prematurely, or what contaminants are driving the change. Monitoring tells you why and what you’re filtering, it’s the key to turning filtration into a reliability tool rather than just a maintenance expense.