When evaluating the effectiveness of air filtration, not all test data is created equal. Two of the most important industry standards for assessing air filters are ASHRAE Standard 145.2 and ASHRAE Standard 52.2. These serve as the foundation for strategies like ASHRAE Standard 62.1-2022's Indoor Air Quality Procedure (IAQP), which uses this data to reduce outdoor air requirements in buildings, thereby unlocking energy savings and reduced capital equipment without compromising health or code compliance. These testing protocols provide standardized, repeatable performance metrics that allow for fair comparison across products. However, to apply them effectively, it is essential to understand what each test measures, how airflow influences results, and how to interpret the data when evaluating different air purification technologies. ASHRAE Standard 145.2: Gas-Phase Contaminant Removal ASHRAE Standard 145.2 outlines a method for testing the performance of gas-phase filtration systems. This includes systems that reduce volatile organic compounds (VOCs), such as formaldehyde, as well as ozone, and other chemical and gaseous pollutants from the air. This standard evaluates the single-pass removal efficiency of air filtration by introducing specific gaseous contaminants into a controlled test duct, then measuring the removal efficiency through the filter in a single pass. Key Considerations: Results are reported as a fractional removal efficiency (e.g., 60% reduction in formaldehyde in a single pass). The test is conducted at the manufacturer’s specified airflow rate (CFM), which directly affects removal efficiency. Because airflow determines contact time between air and filter media, higher flow rates can reduce efficiency even with the same media. For example, formaldehyde removal efficiency typically increases at lower airflow rates, since the contaminant has more time to interact with the filter media. It is therefore critical that the design airflow at which the filter will operate in real-life conditions matches the airflow used in the test data to ensure the reported performance is achievable in practice. ASHRAE Standard 52.2: Particulate Matter Removal ASHRAE Standard 52.2 is the industry standard for evaluating performance of air-cleaning devices as a function of particulate size. It specifically focuses on the removal of particles ranging in size from 0.3 to 10 microns, including PM2.5 and PM10. Key Considerations: Provides Minimum Efficiency Reporting Value (MERV) from 1 to 16 (higher is better). Measures efficiency across three particle size ranges: 0.3–1.0 µm, 1.0–3.0 µm, and 3.0–10.0 µm. Like 145.2, the test is performed in a controlled test duct at a defined airflow rate determined by the manufacturer. Why Airflow (CFM) Changes Everything Both ASHRAE standards measure efficiency at the airflow rate (CFM) the system is expected to operate under typical conditions. The airflow directly influences the results. Unfortunately, not all manufacturers test at the same airflow rate, nor do they consistently disclose this information. Why airflow rate matters: Lower airflow results in higher removal efficiency, as contaminants spend more time in contact with the filter media. Higher airflow results in more volume of air cleaned at the cost of lower single-pass efficiency. A balance is needed between efficacy and throughput. Air purifiers operating at lower CFM will often report higher removal efficiencies yet may clean a smaller total volume of air over time. Conversely, a unit with a lower removal efficiency but higher airflow may deliver more total clean air per hour. To make apples-to-apples comparisons, look at efficiency and tested airflow, or even better, calculate the Cleaned Air Rate (CAR) if both values are provided: CAR = Efficiency (%) × Airflow (CFM) For example: A purifier that removes 90% of a given contaminant at 500 CFM delivers 450 CAR. Another unit that removes 70% of the same given contaminant at 800 CFM delivers 560 CAR cleaning more air, faster, even with a lower efficiency rating. How to Compare Air Purifier Performance When comparing different air purifiers, keep these tips in mind: Verify the testing standards used: Make sure the product was tested according to recognized ASHRAE standards (such as 145.2 for gas-phase and 52.2 for particulate). Be cautious of self-defined standards that don’t provide meaningful or comparable data. Ask for airflow rates used during testing: Without that, efficiency numbers are only part of the story. Consider total performance: Pairing high-efficiency filtration with a smart operating system that balances airflow, pressure, and filter loading gives a better long-term solution. Look at Cleaned Air Rate (CAR): Units with higher CFM often deliver higher CAR, meaning they can clean more air faster. This can reduce the number of units needed for a space, cutting costs on equipment, installation, and ongoing maintenance. Match performance to your environment: Depending on the types of contaminants present, it may be more important to prioritize high removal efficiency for specific pollutants, such as formaldehyde, ozone, or PM2.5, rather than selecting the unit with the highest overall average efficiency. IAQP and ASHRAE Testing Standards The Indoor Air Quality Procedure, detailed in ASHRAE Standard 62.1-2022, allows facility managers and engineers to reduce outdoor air intake requirements if they can demonstrate that indoor contaminants of concern are controlled through filtration or other means. To comply with IAQP, manufacturers and system designers must show that the air purification system installed can effectively control the contaminants listed in Table 6-5, such as PM2.5, ozone, formaldehyde, and other VOCs. This is where third-party test data from ASHRAE Standards 145.2 and 52.2 becomes essential. These results are entered into the IAQP calculator to verify that indoor pollutant concentrations will remain below threshold levels as outdoor airflow is reduced. By using IAQP and equipment tested to these standards, buildings can significantly lower their reliance on outdoor air. This results in major energy savings, reduced HVAC load, and fewer installed units, all while maintaining compliance with ventilation codes and protecting occupant health. A Smarter Approach to Indoor Air Quality Decision-Making Understanding ASHRAE Standards 145.2 and 52.2 is essential for evaluating air purifier performance with real-world relevance. These standardized test methods support informed decisions, especially when using IAQP under ASHRAE Standard 62.1-2022 to reduce ventilation requirements. It is the manufacturer’s responsibility to have testing conducted by an independent laboratory to obtain credible, verifiable results. However, efficiency numbers alone don’t tell the full story. Always consider the airflow rate used during testing, the specific contaminants of concern in your space, and how the Cleaned Air Rate (CAR) aligns with your building’s needs. The goal isn’t just achieving high efficiency, but ensuring smart, effective air quality management that delivers measurable results in both occupant health and operational savings. AirBox: Engineered to Meet the Standards That Matter AirBox High-Volume Purifiers (HVPs) are engineered with these standards in mind. The AirBox HVPs are tested at real-world airflow rates and backed by third-party data to ensure reliable, code-compliant performance. Whether your facility requires high removal efficiency for specific contaminants or a high-CAR system to treat large volumes of air, AirBox offers solutions that align with ASHRAE Standards 145.2, 52.2, and the IAQP pathway. Each unit is paired with our Advanced Operating System (AOS), which intelligently manages airflow, pressure, and filter loading to maintain consistent performance over time. AirBox systems are built not just to meet performance claims on paper, but to deliver measurable results in the field. Thus, helping you improve indoor air quality, reduce energy consumption, and simplify compliance with ASHRAE. To learn more about air purification testing and the specific requirements tied to these contaminants, check out ASHRAE’s Addendum g here ...

HEPA filtration is more than a buzzword—it’s a benchmark for critical environments that can’t afford compromised air. Used across industries where air purity is non-negotiable, certified HEPA (High-Efficiency Particulate Air) filters are the proven choice for removing harmful particulate matter that threatens both human health and sensitive processes. Industries That Rely on True HEPA HEPA, the gold standard of filtration, is widely used in sectors that demand the cleanest air possible, such as: Semiconductor manufacturing Nuclear containment Biotech and pharmaceutical labs Microchip and electronics production Hospital operating rooms and isolation wards Aerospace cleanrooms High-containment BSL laboratories Defense and military applications Food and beverage clean processing If these industries trust HEPA to protect critical operations and human health, it raises an important question: why wouldn’t your facility? What Makes a HEPA Filter Legit? Not all “HEPA” claims are created equal. True, certified HEPA filters must meet strict performance standards—specifically capturing 99.97% of particles at 0.3 microns or better (some certified filters even test to 99.99%). But how do you verify that the filter in your system is performing as it should? Here’s what you should ask any air purifier manufacturer or vendor: Is the filter certified to IEST-RP-CC001? Do your filters meet or exceed ASHRAE Standard 52.2 testing? Do you have ISO 29463 or EN 1822 classification data? Can you provide independent lab results or certification documentation? What DOE (Department of Energy) or cleanroom-grade standards do you meet? Without answers to these, you may be buying a label—not a real solution. The Danger of PM2.5: Invisible, But Potent One of the biggest threats to indoor air quality today is fine particulate matter smaller than 2.5 microns (PM2.5). These particles can penetrate deep into the lungs, enter the bloodstream, and contribute to long-term health problems such as respiratory diseases, cardiovascular issues, cognitive decline, and even cancer. Because they’re invisible to the naked eye, PM2.5 often goes undetected without proper filtration in place and can be found around you in: Vehicle exhaust (diesel and gasoline engines) Industrial emissions (factories, power plants, refineries) Pollen Combustion byproducts (from burning wood, coal, oil, or natural gas) Cigarette smoke and secondhand smoke Wildfire smoke Cooking fumes (especially frying, grilling, and burning oils) Construction dust (fine dust from concrete, drywall, etc.) Agricultural burning and field dust Mold spores Biological fragments (skin flakes, bacteria, organic debris) Brake and tire wear particles (from roadways and traffic) Indoor dust (resuspended fine particles from surfaces or carpets) These microscopic pollutants are all around us—indoors and out—and their ability to bypass the body’s natural defenses makes them especially dangerous. Certified HEPA filters actively capture PM2.5 and even smaller particles with verified efficiency, unlike standard filters, making them one of the most effective tools for protecting indoor air quality. In environments where health, safety, and compliance matter, HEPA isn’t just a filter; it’s peace of mind. HEPA and IAQP The Indoor Air Quality Procedure (IAQP) provides building designers with flexibility to reduce outdoor air ventilation by demonstrating control of indoor contaminants. However, success depends on the effectiveness of the filtration system. While HEPA filtration isn’t explicitly required under IAQP, it’s hard to justify using anything less when PM2.5, one of the most dangerous and pervasive airborne pollutants, is listed in ASHRAE’s Table 6-5. HEPA filters, proven to capture 99.97% or more of particles down to 0.3 microns, offer unmatched protection against PM2.5. Beyond health, better filtration means you can confidently lower outdoor air intake, which reduces HVAC equipment sizing, capital costs, and long-term energy consumption. In short, using HEPA with IAQP isn’t just a win for indoor air quality, it’s a strategic move for cutting costs and future-proofing your building. AirBox: Built on 30+ Years of Cleanroom Expertise At AirBox, HEPA filtration isn’t a new feature, it’s the foundation. With over 30 years of experience in cleanroom design and certification, we understand what proven performance means in environments where there’s no room for error. That’s why every AirBox purifier, ranging from 500 CFM to 9,000 CFM, is equipped with certified HEPA and Advanced Molecular Adsorbent filtration for complete protection. We don’t just say “HEPA”, we prove it. With our Advanced Operating System (AOS), filter life tracking, and IAQP compliance support, we make it easy to bring cleanroom-level air quality into commercial buildings, schools, healthcare facilities, and more ...