“My Laboratory Smells!”: Addressing Odors in the Laboratory

Odors are an emotional issue in any laboratory. If you can smell something you would be less than human if you did not worry that you were potentially being exposed to harmful chemicals. Supervisors are often run ragged trying to find the source of smells and odors in a laboratory. Safety personnel are driven to distraction by the need for repeated personnel sampling and area monitoring to determine if there is or is not a hazard based on someone smelling something, somewhere, at some point in time.

The reasons for odors in a laboratory are many and varied. Some compounds, such as amines and aldehydes, are incredibly odorous and defy any attempt at all but the most rigorous and demanding prudent practices to avoid odors. And even these are occasionally less successful than desired due to occasional trivial errors and lapses in procedures. Most other compounds can be dealt with successfully by proper operating procedures, care in handling and storage, and a few other prudent operating practices.

What are the common causes of odors in a laboratory?

First and foremost, is poor handling practices. Pouring liquid from a bottle outside the hood is guaranteed to generate at least some odors throughout the lab. Transferring liquids further away than the design distance from a local exhaust is a similar problem area. This is often aggravated by the fact that few laboratory personnel have any clue what the design distances for their local exhaust are to be effective.  Transferring liquids too close to the front of a hood) can create problems as is using a hood which is blocked by larger equipment rendering it less effective in capturing vapors.

After any transfer operation the bottles, glassware, and containers should be inspected for residual materials and spills on the surface. If these are not cleaned up immediately, they will invariably evaporate and create odors throughout the lab. Cleaning them up creates its own problems. The paper towels or wipes used to clean up these surface spills, as well as any small spills that occurred during transfer or handling operations, invariably smell badly. All too often they are simply tossed in a trash can and allowed to contaminate the entire lab. Occasionally they are placed in a sealed trash can, usually for fire protection, but these often are not much better; if they are used frequently enough, every time they are opened, they release vapors to the laboratory. A better but more tedious practice is to bag and seal the soaked towels and wipes before depositing them in the trash. Disposal glove are a similar issue if any of the materials got on the glove.

Other common problem areas include hoods which are not working properly. NFPA 45 Fire Protection for Laboratories Using Chemicals requires all that all hoods must be tested and certified to be operating properly at least annually. On numerous inspections I have found hoods well past their inspection date and long overdue for testing. In other laboratories I have found the testing revealed significant problems but no corrective action was undertaken. Most commonly portions of a hood are not working properly because of large solid objects that do not belong in the hood. (See “Why Can’t We Put It In the Hood?”, https://www.linkedin.com/pulse/why-cant-we-put-hood-richard-palluzi/ and “Why Don’t We Just Put It in the Hood?”: Issues with Degrading Hood Effectiveness Due to Equipment Placement, (ACS J. Chemical Health & Safety, Jan, 2020) for a more detailed discussion.) Another very common problem, rigorously ignored by many laboratories, is research personnel opening their hood sashes past their design limits. (See Limiting Hood Openings: A Bad Idea, https://www.linkedin.com/pulse/limiting-hood-openings-bad-idea-richard-palluzi/ for further discussion of this topic.)

Ventilated enclosures are even more problematical as many receive no annual certification and most are so poorly designed that they do not capture vapors properly. (See Ventilated Enclosures: Why Do They Often Fail to Work Properly, https://www.linkedin.com/pulse/ventilated-enclosures-why-do-often-fail-work-properly-richard-palluzi/ for more information.)

Even when a hood or ventilated enclosure is working properly it often fails to capture all the vapors because it is not used properly. Large solid objects inside the hood block the exhaust leading to a dead space and resultant odor release into the laboratory as discussed above. Operations take place too close to the front of the hood and allow vapors to escape. To be effective, operations need to take place at least 6 inches into the hood for effective vapor capture.  

Some researchers move too quickly and rapidly moving things into and out of a hood. This can cause vapors to escape. Operators fail to change their gloves frequently enough and carry trace amounts of liquid throughout the lab creating more odors. As discussed above, throwing paper towels the gloves in the trash create issues.

Flammable storage cabinets are often considered the source of odors in a lab due to the materials stored inside. Rarely have I opened a flammable storage cabinet and not smelled something. Even more rarely are flammable storage cabinets the real source of odors in a laboratory.  Requests to ventilate flammable storage cabinets are common but there are significant safety issues with this practice. To do it safely and maintain the cabinet’s required approvals is costly and requires appropriate design. (See Should You Vent a Flammable Storage Cabinet?, https://www.linkedin.com/pulse/should-you-vent-flammable-storage-cabinet-richard-palluzi/ for further discussion.) In most cases the odors coming from the flammable storage cabinet are due to the poor handling practices that put the bottles away either too loosely capped or not cleaned of residual material on the outside. In other cases, higher temperatures due to off hours setbacks in temperature control generate enough of a temperature rise to cause the bottles to leak and off gas. The total leakage is usually trivial but can create odors. Well ventilating the flammable storage cabinet can help it is expensive and usually procedural changes are much more effective.

Other causes of odors include used glassware awaiting cleaning stored out in the open, spatulas and similar equipment awaiting cleaning, residual trivial spills on lab coats, lab surfaces, balances, and similar equipment; all add to the odors in a laboratory.

So how do you prevent odors in a laboratory? Here are some simple guidelines.

·        Make sure your hoods and ventilated enclosures are tested annually and working properly. Stop using any that are more than 20% below their design face velocity or have areas below this amount.

·        Clear out large bulky objects that do not belong in a hood.

·        Make sure all operations take place at least 6 inches inside the face of the hood.

·        Label the capture distance clearly on snorkels and other ventilated exhausts for the user to be aware of the proper spacing. Don’t know what it is? Get your HVAC designer or a specialist to calculate it out for you or your IH support to measure it for you.

·        Don’t throw anything that contained or soaked up odorous materials in the garbage unless it is in a sealed plastic bag. Use self-closing garbage cans wherever possible.

·        Clean off beakers, glassware, and any equipment used to handle odorous materials immediately. In some cases where these materials are very prevalent, a wash sink inside a hood or ventilated enclosure may be necessary.

·        Make sure all bottles are tightly capped after use. If the material or room temperature varies, rechecking the caps every day or after every change in room temperature may well be prudent.

·        Make sure all bottles are wiped clean after every use and that the towels are disposed of properly as discussed above.

·        Change out gloves and lab coats that have had odorous materials spilled on them as soon as possible. Lab coats should be placed in a sealed bag while awaiting cleaning is the spill is noticeable or at least a sealed cabinet.

·        Identify areas and operations that may require local exhaust, ventilated enclosures, or even an additional hood to allow them to take place without creating odors.

What does not help eliminate laboratory odors? Increasing the laboratory’s ventilation rate is rarely effective unless you can achieve very high and exceptionally costly air changes per hour. Following the procedures above are much more effective and much less costly (both initial capital and annual operating costs).