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Wafting is the practice of fanning vapor from a container toward your nose with a hand or a folded sheet of paper, instead of putting your nose over the opening and inhaling. It is a harm-reduction fallback for the few situations where a chemical has to be smelled, not a way to identify or test a substance. The National Research Council’s laboratory safety reference says sniffing chemicals is generally not encouraged, and that toxic or unknown compounds should never be deliberately sniffed.
Short answer
Wafting means moving a small amount of vapor toward your face rather than bringing your face to the vapor. Under Prudent Practices in the Laboratory (National Academies Press, 2011), it is the approach described for a controlled instructional setting, where students may be told to sniff the contents of a container. It does not make an unknown or hazardous chemical safe to smell, and odor should never be treated as a safety test.
Definition and scope
In laboratory practice, wafting is a way of reducing the dose of vapor that reaches the nose when smelling is unavoidable. Lab Manager, a trade publication, describes it as a harm-reduction method rather than a way of detecting a substance, and advises against putting your nose over an open container. The word comes up mainly in teaching labs, where an instructor asks students to note an odor as part of identifying a known compound.
Scope matters. Wafting applies to deliberately smelling a known, low-hazard material under instruction. It is not a way to check for a leak, to work out what an unlabeled bottle contains, or to decide whether a ventilation system is working. For those jobs, labs rely on labels, safety data sheets and engineering controls. See our guides to how to read a safety data sheet and what a fume hood does.
How the National Research Council describes it
The clearest primary-source treatment is in Prudent Practices in the Laboratory: Handling and Management of Chemical Hazards (National Research Council, 2011), Chapter 6, which the National Academies publishes online. Sections 6.C.2.3 and 6.C.2.4 form a ladder from absolute rule to narrow exception:
| Practice | What the text says | Section |
|---|---|---|
| Tasting | “Laboratory chemicals should never be tasted.” | 6.C.2.3 |
| Sniffing, general rule | “Only in certain controlled situations should any laboratory chemical be sniffed.” The practice is “In general, the practice is not encouraged.” | 6.C.2.4 (Avoiding Inhalation of Hazardous Chemicals) |
| Toxic or unknown chemicals | “Toxic chemicals or compounds of unknown toxicity should never be deliberately sniffed.” | 6.C.2.4 |
| Instructional setting | A footnote notes that in a controlled instructional setting students may be told to sniff a container’s contents, that the chemical should be screened ahead of time to ensure it is safe to do so, and that, if instructed, you “gently waft the vapors toward your nose using a folded sheet of paper” and “Do not directly inhale the vapors.” | Footnote to 6.C.2.4 |
Checked 2026-10-29. Notice where wafting sits: it is a footnote to a section whose main message is to avoid inhaling hazardous chemicals. The technique is the exception, not the recommendation.
Why odor is not a safety test
Treating smell as a hazard alarm is a common mistake. Nothing in the National Research Council’s storage guidance tells staff to rely on odor as a warning. Its chapter on managing chemicals points the other way: volatile toxic or odoriferous chemicals belong in controlled storage (section 5.E.1: “Store volatile toxic or odoriferous chemicals in a ventilated cabinet”), and because many odoriferous substances make their presence known despite efforts to contain them, such items should be aggressively purged from storage and inventory (section 5.D.1).
The OSHA Laboratory Standard, 29 CFR 1910.1450, mentions odor in one place: its training requirement says employees should be trained on methods to detect a chemical’s release, including its “visual appearance or odor.” Appendix A to the standard adds that ventilation should keep “odoriferous or toxic substances” from increasing during the workday. The standard text (checked 2026-10-29) does not tell anyone to sniff a chemical, and it does not forbid it either. The same training item lists monitoring by the employer and continuous monitoring devices alongside odor, so odor is one cue among several, not a method for identifying a substance.
Where it matters for labs and clinics
For lab managers and safety officers, the value of understanding wafting is in writing clear rules, not in teaching the technique to everyone. A short checklist, each item traceable to the sources above:
- Is smelling the only option? The National Research Council’s default is that sniffing is not encouraged, so identification should come from the label and the safety data sheet first.
- Is the chemical known, and is it not toxic? Toxic or unknown-toxicity compounds are never to be deliberately sniffed (6.C.2.4).
- Is this a controlled, instructed setting? The wafting footnote is framed around instruction, with a person directing it.
- Are storage and ventilation doing the work? Odoriferous and volatile toxic chemicals go in ventilated storage (5.E.1), and the Laboratory Standard expects ventilation to keep odors from building up.
- Does your respiratory protection program cover the hazard? If vapor exposure is a real concern, that is a question for engineering controls and your respiratory protection program, not for wafting.
To decide whether any sniffing is ever appropriate in your setting, review your own hazard assessment and chemical hygiene plan (see laboratory safety and the chemical hygiene plan).
Common misunderstandings
“Wafting makes any chemical safe to smell.”
It does not. It lowers the amount of vapor reaching you; it does not change what the chemical is. The National Research Council text still says toxic and unknown compounds should never be deliberately sniffed.
“OSHA requires or bans wafting.”
The text of 29 CFR 1910.1450 and its Appendix A, as checked on 2026-10-29, mentions odor only in the training item on detecting releases and in the ventilation guidance. It does not address sniffing or wafting. Check your own institution’s chemical hygiene plan for any local rule.
“If I can’t smell it, it isn’t there.”
The OSHA text treats odor as one cue next to monitoring methods, so it should not be your only check. Use ventilation, the safety data sheet and your hazard assessment instead; see our guide to the hazard communication standard in laboratories.
“Wafting is a way to identify an unlabeled bottle.”
Unknown compounds are the case where the National Research Council says never to sniff. An unlabeled container should be handled through your lab’s unknown-chemical procedures, not by smell.
FAQ
What does wafting mean in chemistry?
It means gently fanning vapor from a container toward your nose, rather than inhaling directly over the opening. The National Research Council’s footnote describes using a folded sheet of paper and not directly inhaling the vapors.
Is it safe to waft any chemical?
No. Toxic chemicals and compounds of unknown toxicity should never be deliberately sniffed, according to section 6.C.2.4 of Prudent Practices in the Laboratory.
Is sniffing chemicals allowed in a lab?
Only in certain controlled situations, and the practice is generally not encouraged, per the same source. Your institution’s chemical hygiene plan may set stricter rules.
Does a fume hood replace wafting?
They address different things. A fume hood is an engineering control that captures vapor; see what a fume hood is. Neither makes sniffing an unknown chemical acceptable.
Sources
- National Research Council, Prudent Practices in the Laboratory: Handling and Management of Chemical Hazards (2011), Chapters 5 and 6, National Academies Press: https://www.nationalacademies.org/read/12654/chapter/7 and https://www.nationalacademies.org/read/12654/chapter/6 (checked 2026-10-29).
- OSHA, Occupational Exposure to Hazardous Chemicals in Laboratories, 29 CFR 1910.1450 and Appendix A: https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1450 (checked 2026-10-29).
- Lab Manager, “Smelling a Chemical: The Wafting Technique”: https://www.labmanager.com/smelling-a-chemical-the-wafting-technique-19098 (trade press; checked 2026-10-29).
