Fume Hood Safety Series: What Is a Good Metric for Judging a Hood’s Safe Performance?
Chip Albright, founder and president of Fume Hood Certified; 2025 Lab Design Conference workshop leader; Fume Hood Risk Mitigation Digital Conference speaker
Chip Albright, founder and president of Fume Hood Certified, is a globally recognized authority in laboratory safety and equipment, specializing in fume hood performance. With more than 40 years of industry experience, he offers extensive knowledge of safety standards, regulations, and cutting-edge technological advancements. In this Fume Hood Safety Series, he shares valuable insights and cautions for professionals involved in laboratory design, construction, and renovation.
Chip will be leading a workshop on “Validating Fume Hood Safety and Mitigating Risk” at the 2025 Lab Design Conference in Denver on May 11. Register now to secure your spot in this workshop, as space is limited! (Please note: This workshop is a separate add-on to your Lab Design Conference ticket.)
Additionally, you can watch Chip’s free on-demand webinar, “Your Chemical Fume Hood Is On Fire: What Do You Do?” from the Fume Hood Risk Mitigation Digital Conference. Register now to access the free webinar, and contact us at aia@labdesignconference.com to earn AIA LU/HSW credit for completing the video.
When it comes to laboratory fume hoods, the key question should not be, “What is the average face velocity?” but rather, “Is the hood safely containing hazardous substances under real-world conditions?” For decades, the laboratory safety community has leaned heavily on average face velocity as a proxy for hood performance. While face velocity is easy to measure, it is not an accurate metric for judging the hood’s safe performance.
Let’s be clear: safe performance equals containment. The core function of a fume hood is to protect the user from chemical exposure by capturing, containing, diluting, and exhausting harmful substances. If a hood fails to contain, it fails to perform—regardless of the face velocity reading.
Face velocity simply measures how fast air is entering the hood. It gives a “snapshot” of airflow at a given moment. But airflow is dynamic, influenced by the movement of people, temperature gradients, cross drafts, door openings, and other variables. Studies show that more than 70 percent of hoods that perform poorly in containment testing still meet face velocity targets. So clearly, velocity does not predict containment.
A better metric is dynamic containment testing, such as the ASHRAE 110 protocol, especially when paired with tools like smoke visualization or tracer gas. These tests simulate real-world conditions—objects inside the hood, operator movement, and fluctuating room conditions—to evaluate whether contaminants escape into the lab. Dynamic testing highlights areas where turbulence or instability may compromise safety.
Turbulence is the enemy of containment. Even with “acceptable” face velocity, unstable airflow patterns can cause chemicals to escape into the user's breathing zone. Visual tools like the Tri-Color Airflow Visualizer now allow users to actually see these air currents in action, identifying areas of concern that velocity meters alone would miss.
A comprehensive face velocity profile, rather than a single average reading, is also more valuable. A profile maps velocity at various points across the hood face, offering clues about uneven flow or turbulence. But again, this is diagnostic information—not the final word on performance.
We also need to shift our mindset from standard compliance to risk-based evaluation. How often does a hood fail to contain? What is the magnitude and duration of leakage? What chemicals are involved, and how toxic are they? How long is the operator exposed? These are the questions that define safe performance.
To sum it up: Containment, not face velocity, should be the benchmark for hood safety. Safe performance means the hood reliably captures and contains hazardous substances under realistic working conditions. Anything less is unacceptable, because when it comes to lab safety, “everything was fine—until it wasn’t.” Prevention isn’t just smart—it’s a bargain.
Having a fume hood and having one that is performing safely are two totally different things. It’s time the metrics we use reflect that truth.
