The Sheri Sangji case is the first criminal case resulting from an academic laboratory accident. The fatal incident occurred on December 29, 2008, when research assistant Sheharbano Sangji suffered severe burns for not wearing a protective lab coat and her clothing caught fire. She was using a syringe to transfer pyrophoric reagent tert-butyllithium from one sealed container to another, with a result of spilling the chemical and igniting a fire. She died 18 days later. The UCLA was fined for willful violation of safety regulations.
Accidents like this demonstrate that having a fume hood in a laboratory is only the first step to provide a safe environment for researchers. It is essential to have the proper personal safety training when working within the hood, to guarantee the safety of the user.
There are some basic tips to bear in mind to keep safety in the laboratory.
1. Maintenance: Check the equipment at least once a year. Be alert of any defect or potential malfunction. Although some models have an alert in case of a malfunction, even monitor may cease working correctly. The fume hood is an expensive equipment to replace, so periodic maintenance schedules and correcting problems prevent inconveniences. Report to upper management as soon as any abnormality is observed.
2. Protocols: Keep instructions nearby, close to each equipment, in a visible place, so everyone who uses the lab (technicians, researcher, students, workers) understand the maintenance of the equipment.
3. Airflow: The basic security tip is airflow. Check that the airflow of the room and hood’s surroundings are properly channeled prior to each use. Also, windows and doors in the lab should be closed. Make sure there is nothing blocking the air flow through the baffles in the back. It is important to adjust the baffles to catch the vapours and gases properly.
4. Vapours: vapours disperse into their surroundings so keep all materials at approximately 6 inches away when working in the hood. Fume hoods do not protect from explosions, so do not introduce your head inside the working area. It is essential that the user knows what he/she is working with and the protocols in case of an emergency.
5. Chemicals: Fume hoods have specific models according to the chemicals used. Use the fume hood according to the chemicals and reactions you manipulate in your lab. Do not take for granted that a high-quality fume hood can handle other substances different from the ones it was designed. Besides, chemicals should be placed fully under the hood, beneath the vents. Manipulating substances close to the exterior do not prevent escaping vapours into the lab environment.
6. Sash Levels: to maximize airflow and safety, work at or below the marker of height requirements. Never force the mechanic of the sashes. The window of the hood has to be cleaned and easy to see through. Be sure there is no sight obstruction.
7. Concentration: Fume hoods should be in low traffic areas within the room to minimize the disruption of the hood user’s concentration. Also, windows should be clear, without sticks or marker notes. It is essential to have the light switched on to see better and avoid accidents.
8. Clean working area: Fume hoods are not for storage or disposal of waste materials, so once you have finished working, remove everything. Also, minimize the number of items placed around the working place area
9. Wear PPE. Use additional protection such as gloves, lab coat and goggles to protect against an accidental spray.
10. Follow manufacturer instructions.
Fires in fume hood are very frequent when not following protocols. The University of Delaware reported a fire in a fume hood caused by not cleaning properly the fume hood after use. The researcher was running a synthesis reaction using a hot plate and an oil bath. When he finished, he left the hot plate on high (instead of turning off). The oil heated up and caught fire, involving a solvent stored in the hood. A user who came later saw the fire and extinguished it on time.
Frequently asked questions.
What should I do once I have finished using the fume hood?
There are three basic steps to bear in mind once you have used the fume hood. First, clean the fume hood and working surface. Second, close the sash and keep it working for 15 to 30 minutes until all generated contamination has been eliminated. Finally, remember that the food hood is not for storing substances: never leave chemical, materials or equipment in the fume hood.
How can I know that my fume hood is working properly?
A good fume hood should have a monitor that controls the airflow. It should have an alarm system in case of contingency and the velocity has to be monitored.
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