TL;DR
- Never use a fume hood as chemical storage; it restricts airflow and creates a safety hazard.
- Keep large equipment, paper, cloth, and food out of the hood entirely.
- Flammable solvents require a certified explosion-proof (spark-free) fume hood; a standard hood is not safe for them.
- Certain materials — radioactive substances, biological agents, perchloric acid — require specialized containment, not a standard chemical fume hood.
The Short Answer: What Doesn’t Belong in a Fume Hood
A fume hood protects you by pulling contaminated air away from your breathing zone. Anything that blocks that airflow, reacts unpredictably with other materials, or belongs in a different containment system undermines that protection. If you’re setting up a small lab and aren’t sure what’s safe to put in the hood, this covers the most common mistakes and why they matter.
Why Clutter Is a Bigger Problem Than It Looks
Storing items inside a fume hood reduces face velocity, which is the speed at which air moves across the work surface and away from you. When face velocity drops below the recommended 100 feet per minute (FPM), fumes can escape into the room instead of being captured.
The most common culprit in small labs is treating the fume hood like a convenient shelf. Bottles, spare equipment, and tools pile up over time, and airflow suffers before anyone notices.
What to keep out:
- Chemical bottles not actively in use
- Lab notebooks, loose paper, or printed protocols
- Cloth materials (rags, wipes, paper towels stored in quantity)
- Equipment that runs between experiments but doesn’t need to be in the hood
Keep only what you need for the current procedure inside the hood at any given time. Everything else goes on a shelf or in designated storage.
Chemical Storage Inside a Fume Hood
A fume hood is not a storage cabinet. Storing chemicals inside one is one of the most common lab safety violations, and it compounds risk in two ways: it blocks airflow and concentrates reactive materials in a single location where a spill or reaction could trigger a chain event.
Store chemicals in:
- Flammable storage cabinets (FM or UL-listed) for flammable liquids
- Corrosive cabinets for acids and bases
- Ventilated cabinets for materials that off-gas at room temperature
Only bring chemicals into the hood when you’re actively working with them.
Large Equipment That Disrupts Airflow
Bulky equipment placed inside a fume hood creates turbulence and shadow zones behind the object, where fumes can accumulate rather than being captured and exhausted.
This is a real issue in small labs where bench space is limited and the fume hood looks like the easiest place to park a rotary evaporator, a heating mantle, or a recirculating chiller between uses.
Common items that should stay outside the hood unless actively in use:
- Rotary evaporators
- Water baths and recirculating chillers
- Hot plates not directly involved in the current procedure
- Vacuum pumps (these should be located outside the hood, connected by tubing)
If equipment must operate inside the hood, position it at least 6 inches back from the sash to minimize turbulence at the face.
Materials That Require a Different Containment System Entirely
A standard chemical fume hood is not appropriate for radioactive materials, biological agents (BSL-1 through BSL-4), or perchloric acid. Each requires a specialized containment system with different design requirements.
This distinction matters for small labs because the equipment looks similar and the mistake is easy to make.
Radioactive materials require a radiological fume hood with appropriate shielding and HEPA filtration, operated under NRC licensing requirements.
Biological agents require a biosafety cabinet (BSC), not a fume hood. A BSC protects the work, the worker, and the environment through HEPA filtration. A chemical fume hood provides no such protection.
Perchloric acid requires a dedicated perchloric acid hood with a wash-down system. Perchlorate residue buildup in standard ductwork creates a serious explosion hazard.
If you’re unsure which containment system applies to a material you’re working with, consult your chemical hygiene officer or contact the manufacturer of the agent before proceeding.
Food, Drink, and Personal Items
Food and drink do not belong in or near a fume hood. This is both a contamination risk and a regulatory compliance issue under Good Laboratory Practice (GLP) standards.
This is straightforward. Fume hood workspaces are not clean zones; they handle hazardous materials by design. Bringing food or drink into that environment introduces a direct ingestion exposure pathway.
The same applies to personal items such as phones, notebooks, and bags. These surfaces can transfer contaminants out of the lab.
Wrapping It Up
Maintaining safety in laboratories relies on the correct use of fume hoods. It’s crucial to refrain from using them for storage, keeping them free from clutter and large equipment, and never bring food, drinks, or non-lab items near them. By adhering to these practices, lab workers can create a safer and more efficient workspace. Remember, the key to safety and efficiency in the lab is not just the equipment itself, but how we utilize it.
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