By: K. Lee Stone


Lee Stone has a Master's degree in toxicology from Indiana University and is a certified Chemical Hygiene Officer. Lee has served as the Laboratory Safety Manager for the Office of Environmental Health and Safety since 2004.

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Safety in Numbers

We have all heard the saying that “there is safety in numbers”. This is particularly true in laboratories where the numbers 0 and 1 can prove fatal, or result in the destruction of a building. I am referring to working alone and to unattended operations in laboratories.


It is good laboratory practice to avoid working alone, particularly when working with acutely toxic chemicals, pyrophoric chemicals or hazardous equipment. There have been two fatal accidents in laboratories in recent years that occurred while working alone. One involved working alone in a laboratory with hazardous chemicals and a second death occurred while working alone with hazardous equipment. The first was a fatal fire that occurred in a laboratory where a graduate student was working alone with a pyrophoric chemical. Please read more about this accident by clicking on this link: UCLA lab assistant dies. A second death occurred more recently in a small machine shop adjacent to a chemistry lab where a student was working on her senior project. The student was operating a lathe when her hair became entangled in the lathe and pulled her into the machine. Please read more about this accident by clicking on this link: After a fatal accident, new safety standards.


It is impossible to know if working with a fellow student, co-worker or supervisor would have prevented the accidents detailed above, however it may have prevented their deaths. Please learn from these fatal mistakes and do not work alone in laboratories, particularly when hazardous chemicals or equipment are used. This is also a good time to take a close look around your lab. Do you have equipment with moving parts such as vacuum pumps? Do the belts have a protective cover over them? Do you tie back your long hair and confine lose clothing? Do you ever work alone in the laboratory? The answers to these questions may save your life.


Similar to our concerns about working alone, there is the issue of hazardous operations running unattended, often overnight or through the weekends or holidays. Should a problem occur, the results could be very serious indeed. For operations running in a fume hood, what will happen if the power goes out or a hood malfunctions? What would be result of a water failure (or tubing break) in a water-cooled condenser? What if a piece of analytical equipment breaks, jams up or otherwise fails? What happens if the waste container overfills?


I have personally observed the devastating results when unattended operation goes bad. A protein sequencer was running unattended over the weekend and the laboratory occupants did not empty the waste container before leaving. The waste container vented into the fume hood through a tygon tube and when the waste container was full there was no place for the waste to be pumped except through the vent tube into the fume hood. The instrument pumped a highly flammable corrosive waste into the fume hood which pooled in the fume hood and dissolved an electrical cord and the resulting spark ignited the waste. The fire destroyed the fume hood, an entire lab and its contents. The fire suppression system saved the building but flooded all three floors. The water destroyed more equipment and resulted in a very expensive remediation. See the photo below for a view of the fume hood after the fire.

When an operation must run unattended it is critical for lab personnel to carefully evaluate the process. First of all, question WHY the process must run unattended. Can it be done another way, or in an "attended" location within the laboratory? Identify what can go wrong. Establish procedures to mitigate these problems. Identify methods of warning to others in the building should something go wrong.


Below are some points you should consider before leaving any operation unattended:

  • Anticipate potential equipment and facility failures. What will happen if you lose power or cooling water, for example.
  • Empty all waste containers and provide containment for release of hazardous chemicals.
  • Apparatus/equipment should not be left running unless it has been operating satisfactorily for at least one hour beforehand.
  • Experiments that are left unattended must have overriding controls with automatic shutdown devices to prevent system failure that could result in fire or explosion, for example, the loss of cooling water, overheating, flooding, and pressure buildup. Permanent piping, and shields or barriers, if necessary, should be provided.
  • Warning signs must be used if radiation, toxic fumes, or other hazardous conditions are present. Custodians, utility, or security personnel need to be warned of any hazards.
  • Verify that the hazard warning signage posted at the entrance to the door of the lab lists the correct contact names. Ensure their IU Notify information is current.
  • All unattended electrical heating equipment must be provided with fail safe oven temperature shutoff controls, as overheating can result in a fire hazard.
  • Burners, induction heaters, ovens, and furnaces must be located away from areas where temperature-sensitive and flammable materials are handled.
  • Fan-cooled heating equipment must be equipped with an interlock arranged to disconnect current to the heating elements when the fan becomes inoperative.
  • Post a notice on your equipment describing possible malfunctions, emergency shutoff procedures, and the nature of the hazards.
  • Bunsen and other gas burners without approved flame-failure devices must not be left unattended. Gas pressure often fluctuates; an increase in pressure will cause a taller, hotter flame, which will overheat equipment and potentially cause a fire. If the pressure decreases the flame may go out. Upon resumption of gas flow, unburned gas will accumulate to create a fire or explosion hazard.
  • Over-temperature cutoff devices should be used on heated oil baths.
  • Check all tubing. It is recommended that you use permanent piping if you must supply water to an overnight experiment. A sudden rise in pressure, due to water fluctuations, may rupture plastic or rubber experimental apparatus and cause flooding of lower floors.
  • Electrical extension cords should never be left unattended while plugged in. Extension cords are for temporary use while working with portable equipment in rooms where receptacles are not available.
  • Protect the cords of electrical devices that must operate unattended. Prevent chemical or physical damage to the cords, by draping cords away from foreseeable hazards and heat sources.

Remember, there is safety in numbers in a laboratory. Please avoid working alone and ensure that you consider the points above before you leave an operation unattended.


Lab Notes is a quarterly publication by the IUPUI Office of Environmental Health and Safety. Lab Notes is designed, edited and published by K. Lee Stone.

"Don't Learn Laboratory Safety by Accident!"