Tools to help you work safely and effectively

Equipment requirements and safe practices

Autoclaves must be used properly to effectively decontaminate potentially biohazardous materials. The following elements all contribute to autoclave effectiveness.

  • Temperature: Adequate chamber temperature is at least 121°C (250°F).
  • Time: Adequate autoclaving time for biohazardous waste is a minimum of 45 minutes, measured after the temperature of the material being sterilized reaches 121°C and 15 psi pressure. The more densely arranged the autoclave load, the longer it will take to reach 121°C in the center of the load.
  • Contact: Steam saturation of the load is essential for effective decontamination. Air pockets or insufficient steam supply will prevent adequate contact. To ensure adequate steam contact, leave autoclave bags partially open during autoclaving to allow steam to penetrate into the bag.
  • Containers: Use leak-proof secondary containers for items to be autoclaved. Place plastic bags inside a secondary container in the autoclave if liquids leak out. Plastic or stainless steel containers are appropriate secondary containers. Make sure plastic bags and pans are autoclavable.
  • Indicators: Autoclave tape indicators can only verify that the autoclave has reached normal operating temperatures for decontamination. Most chemical indicators change color after being exposed to 121°C, but cannot measure the length of time spent at 121°C. Certain chemical indicators (such as SterigageTM) verify that the autoclave reached adequate temperature for a specified length of time. However, biological indicators such as Geobacillus stearothermophilus spore strips verify that the autoclave cycle is performing properly and will kill microorganisms.
    • Use a chemical indicator in every load to monitor the effectiveness of individual autoclave runs (temperature only).
    • Once a month, use a biological indicator (such as Geobacillus stearothermophilus spore strips). Bury the indicator in the center of the load to validate adequate steam penetration. Keep a logbook to record the results.

Autoclave safety

Autoclaves are classified as pressure vessels. All autoclaves with an internal capacity of 5 cubic feet or larger must be inspected at least annually according to Iowa Code. Repairs to most autoclaves on campus are done by Facilities Planning & Management (FP&M).

Because an autoclave uses saturated steam under high pressure to achieve sterilizing temperatures, proper use is important to ensure operator safety. Prevent injuries when using the autoclave by observing the following rules:

  • Wear heat-resistant gloves, eye protection, closed-toed shoes, and a lab coat, especially when unloading the autoclave.
  • Prevent steam burns and shattered glassware by ensuring the pressure in the autoclave chamber is near zero before opening the door at the end of a cycle. Slowly crack open the autoclave door and allow the steam to escape gradually.
  • Allow items to cool for 10 minutes before removing them from the autoclave.
  • Never put sealed containers in an autoclave. They can explode. Large bottles with narrow necks may also explode if filled too full of liquid.
  • Never put solvents, volatile or corrosive chemicals (such as phenol, chloroform, bleach, etc.), or radioactive materials in an autoclave. Call EH&S at (515) 294-5359 if you have questions about proper disposal of these materials.

Inspect your autoclave components regularly. If you find a problem, notify your area mechanic. Do not operate an autoclave until it has been properly repaired.

Additional resources

What is a biosafety cabinet?

A biosafety cabinet (BSC) is not a chemical fume hood. Fume hoods are designed to remove chemical fumes and aerosols from the work area. BSCs are designed to provide a clean work environment and protection for employees who work with biological hazards. BSCs use vertical laminar airflow to create a barrier to airborne particles like microorganisms. They use High-Efficiency Particulate Air (HEPA) filters to clean air going into the work area and out to the environment. The air in most BSCs is recirculated over the work area through the HEPA filter. The HEPA filter removes airborne particles from the air but does not remove chemical fumes.

When should I use a biosafety cabinet?

Use a BSC to manipulate human pathogens or antineoplastics that will likely create aerosols (such as vortexing open tubes, pipetting, opening caps after centrifuging, sonicating, aspirating with a syringe, etc.). Use for manipulating airborne transmitted pathogens (such as Brucella abortus, Mycobacterium tuberculosis, etc.).

Open flames in a biosafety cabinet

Using open flames, such as Bunsen burners, in a BSC disrupts the airflow, compromising the worker's and the work's protection. In addition, if the burner's flame is too large or ignites a wash bottle of ethanol (often found in a BSC), the excessive heat may melt the adhesive holding the HEPA filter together or burn holes in the filter media. Alternative methods, such as electric incinerators or disposable inoculating loops, are recommended.

Ultraviolet lights in a biosafety cabinet

Remember that the ultraviolet (UV) light in your BSC is only useful as an extra precaution in keeping the work area decontaminated between uses, because UV light has very little power to penetrate even through a dust particle. After each use, thoroughly clean and decontaminate the work area using a chemical disinfectant, such as an iodophor.

Annual certification testing

Improper airflow or filter leaks in a BSC could expose laboratory personnel to biohazardous materials. To ensure that BSCs on campus are providing necessary protection to workers and the environment, it is essential that the BSCs be routinely inspected. EH&S coordinates this service annually for all BSCs on campus that are used to contain biological hazards and will notify you when annual testing will be performed. To schedule your BSC for testing, you must submit an account number to EH&S for the certification testing charge. Testing is done according to the nationally accepted standards of NSF International. Your BSC should have a label stating its last test date (see example).

Moving or repairs

In addition to annual testing, BSCs must be re-tested whenever they are moved or have filters changed. A qualified servicing company must do filter changes and repairs. Call EH&S at 294-5359 to schedule testing or for a referral to a qualified repair company.

Purchasing a new biosafety cabinet

If you plan to purchase a new BSC, notify the Biosafety Officer or Biosafety Specialist at 294-5359 for assistance in choosing the appropriate BSC for your needs and to get the BSC on the schedule for annual certification testing. Use the following criteria when purchasing a BSC:

  • The BSC should be certified by an NSF-accredited technician according to NSF Standard 49. Work with any infectious agents or recombinant DNA classified as requiring Biosafety Level 2 or higher containment will not be permitted in a BSC that does not pass certification testing for containment.
  • Verify with the Biosafety Officer that the BSC type (Class II Type A2, Class II Type B2, etc.) is appropriate for the type of work that it will be used for (type of biological agents to be contained and any chemicals to be used.)
  • If the BSC is a Class II Type A2, the connection to the exhaust must be a thimble connection and not a gas-tight connection.
  • Installation of BSCs must allow access to both supply and exhaust filters for annual certification testing and filter changes:
    • The top of the cabinet must be far enough below the ceiling (at least 18") to allow field testing of exhaust flow according to NSF Standard 49.
    • Any connections to exhaust ductwork must allow access for field testing of exhaust flow according to NSF Standard 49.
  • Any outlets inside the work area of the BSC should be ground fault circuit interrupter (GFCI) outlets.

Additional resources

Use the following practices to prevent aerosols when using blenders, grinders, sonicators, lyophilizers, or similar equipment:

  • Blenders, grinders, sonicators, lyophilizers, etc., should be operated in a biosafety cabinet whenever possible.
  • Safety blenders should be used. Safety blenders are designed to prevent leakage from the bottom of the blender jar and to withstand sterilization by autoclaving. They also provide a cooling jacket to avoid biological inactivation.
  • Avoiding glass blender jars prevents breakage. If a glass jar must be used, it must be covered with a polypropylene jar to contain the glass in case of breakage.
  • A towel moistened with disinfectant must be placed over the top of the blender while operating. This practice can be adapted to grinders and sonicators as well.
  • Aerosols must be allowed to settle for five minutes before opening the blender jar (or grinder or sonicator container).
  • Lyophilizer vacuum pump exhaust should be filtered through High-Efficiency Particulate Air (HEPA) filters or vented into a biosafety cabinet.
  • Polypropylene tubes should be used instead of glass ampoules for storing biohazardous material in liquid nitrogen. Ampoules can explode, causing eye injuries and exposure to the biohazardous material.


Use the following techniques to prevent aerosolization and spills when using a centrifuge:

  • Sealed tubes and safety buckets that seal with O-rings should be used. To avoid spills from broken tubes, inspect all tubes, O-rings, and buckets for damage before each use.
  • Leaks can be prevented by not overfilling centrifuge tubes. The outside of the tubes should be wiped with disinfectant after they are filled and sealed.
  • Rotors and centrifuge tubes should be opened inside a biosafety cabinet. If a biosafety cabinet is unavailable, a minimum of ten minutes of settling time should be allowed before opening the centrifuge tubes.

Check out our Laboratory Safety: Using a centrifuge video (YouTube) to learn more.

A standard chemical fume hood is a fire- and chemical-resistant ventilated enclosure with an opening in front (face) with a moveable window (sash) to allow a user access. It is designed to protect personnel and prevent contaminants from escaping into the laboratory environment.

Use a chemical fume hood when

  • Handling chemicals with inhalation hazards.
  • Conducting procedures with exothermic reactions.
  • Handling materials with significant vapor pressure.
  • Working with chemicals that can cause a fire hazard.
  • Working with compounds that have an offensive odor or unknown toxicity.
  • Heating or using >72% perchloric acid, a specialized fume hood equipped with a wash-down system must be used. Contact for more information.

​​How to verify the fume hood is working properly

  • Check the certification card. EH&S certifies hoods annually; if yours has not been certified in the last year, do not use the hood and contact EH&S.
  • Check monitor. If the monitor reads between 80 and 125 fpm (feet per minute), the hood is pulling an appropriate amount of air. If the readings are less than 80 fpm or more than 125 fpm, do not use the hood and contact EH&S. For monitors without a digital reading, a green light indicates the unit is pulling the appropriate amount of air. Contact EH&S at (515) 294-5359, and do not use if other colors are illuminated.
  • Check tissue paper. For hoods without a monitor, a piece of tissue paper or a Kim wipe taped to the bottom of the sash will indicate the direction of airflow. If the wipe is pulled inside, the unit is pulling air and may be used. If the wipe is pushed out of the hood, DO NOT use the fume hood and contact EH&S.

How to protect yourself and others

Before work
  • Verify the hood is working correctly.
  • Set the sash height (no higher than the arrows on the side).
  • Do not position fans toward the hood.
  • Do not modify the hood design.
During work
  • Keep your head outside of the hood.
  • Avoid rapid movements.
  • Conduct work at least six inches from the front (face) of the hood.
  • Minimize traffic in front of the hood.
  • Do not obstruct the hood opening or baffles; keep items in the hood at a minimum.
After work
  • Clean up the work surface.
  • Limit the storage of materials in the hood; too many items can disrupt the airflow.
  • Lower the hood sash.
  • Make sure all containers in the hood are closed.

If the alarm sounds, stop work, lower or close the sash, and contact EH&S. Do not mute or ignore the alarm. Be sure to notify others that the fume hood is not working correctly. 

EH&S fume hood signage

  • A yellow caution sign indicates that the hood did not meet all safety criteria; however, if operated under specific conditions, the hood can still provide a safe working environment. Conditions for use are listed on the sign.
  • A red warning sign indicates the hood is unsafe and cannot be used for work or storage.
  • EH&S and Facilities Planning & Management (FP&M) will coordinate repairs for the hood; no action is needed by laboratory personnel.
  • EH&S is responsible for sign removal and will only do so when the hood has undergone repairs and passed certification testing.

Compressed and liquefied gases are routinely used in laboratories and other Iowa State operations. The Gas Cylinder Safety Guidelines (PDF) apply to all Iowa State University employees who use or otherwise handle compressed or liquefied gases or systems that use compressed or liquefied gases. The guidelines provide information on the safe use of compressed and liquefied gases and inform employees of potential health and physical hazards associated with gas and cylinder usage.

Iowa State promotes the safe use of gases by offering training and information on the proper storage, handling, usage, and disposal of gases and gas cylinders. Only trained and qualified personnel can use compressed and liquefied gases.

Training should include the associated hazards of the materials, necessary safety precautions, personal protective equipment, and emergency response procedures. Appropriate material safety data sheets, associated "Safetygrams™", or other gas supplier product information shall be made accessible to compressed gas users. Additional information is available via the Compressed Gas Cylinder Training in Workday Learning. Contact EH&S at (515) 294-5359 or Ames Laboratory ESH&A at (515) 294-2153 for the next scheduled class information.

Visit our Compressed Gas Safety page to learn more.

Additional resources

Common heating devices include hotplates, oil baths, furnaces, and drying ovens. Follow these guidelines to use heating devices safely:

  • Keep flammable and combustible material away from the heating devices.​
  • Develop standard operating procedures (SOPs) for all heating operations. 
  • Heating equipment should only be left unattended during operation if precautions have been taken to prevent fire or explosion. Use a well-secured automatic temperature controller for unattended operations.
  • Hotplates have been known to malfunction and overheat, even in the “off” position. Therefore, test the power switch by ensuring the heating device cools quickly after turning it off. Unplug hotplates once they're cooled. 

Oil baths

  • Heating oil baths should be labeled with the safe working temperature range.
  • Mineral oil can break down over time, lowering the flashpoint. Change mineral oil regularly or as it becomes discolored.
  • Any oil that has been overheated must be discarded and replaced.
  • Consider alternatives to mineral oil, such as silicone oil, sand baths, reaction blocks, or metal beads. 

The Laser Safety Factsheet (PDF) provides information on laser classes and laser examples. Iowa State University allows the use of Class 2 and Class 3A/R laser pointers without prior approval. The use of Class 3B and Class 4 laser pointers requires the approval of the Laser Safety Officer.  

Students, staff, faculty, contractors, and visitors are expected to operate lasers safely in campus living/learning spaces, offices, public areas, and outdoors.

    To become an authorized operator of class 3B and/or 4 laser devices, you must:

    1. Complete Laser Safety for Operators training in Workday Learning and successfully complete the Laser Safety exam. Retraining is needed every three years. Learn more about required training for lasers.
    2. If needed, contact Occupational Medicine, (515) 294-2056, located at G11 Technical and Administrative Services Facility (TASF) to schedule a preliminary baseline eye exam. See Section J of the Laser Safety Manual (PDF) for more information.
    3. Complete laser-specific training for each laser that the worker will be using.  See Section F of the Laser Safety Manual (PDF) for the topics to be covered.  A copy of the training contents and an attendance record must be maintained. This is the responsibility of the principal investigator (PI).
    4. Submit the Laser Worker Application. You must list a currently approved PI who has approved your addition to their Laser Authorization.
    5. Submit the Application for Use of Class 3B or Class 4 Laser Form (PDF). 

    Once you have completed all of these steps, EH&S will add you to the PI's authorization and you will be able to use the laser system.

      Laser audits

      EH&S will audit the laser authorization annually. This process will include a laser hazard assessment. A copy of the Laser Hazard Assessment Criteria (PDF) is available for your use.

      Laser signage

      ANSI Z136.1 requires that lasers and laser systems have appropriate warning labels and that the rooms in which they operate bear appropriate warning signs. Signs for laser laboratory doors are provided by the LSO; however, laboratory supervisors and laser users/operators must be familiar with the signage requirements.

      Ordering lasers and laser systems

      The LSO should be contacted prior to ordering Class 3B and Class 4 lasers or laser systems. Including the LSO as part of your ordering process will decrease procurement delays and reduce potential regulatory deficiencies. The LSO can recommend protective measures to consider for the specific device or system.

      Laser pointer safety

      Learn more about Laser Pointer Safety.

      Open flames are not recommended for use in the lab. Open flames generate aerosols, which may contain pathogens. The heat emitted by constant flame disrupts airflow in biosafety cabinets and clean benches and may damage the filters in these units. Open flames present a fire hazard in the lab.

      Alternatives to using an open flame:

      • shielded electric incinerator
      • hot bead sterilizer
      • disposable loops and plastic needles
      • autoclaved utensils and equipment

      If a flame is absolutely necessary, use a Bunsen burner that provides the flame on demand.

      Use the following practices to prevent aerosols and splashing while pipetting:

      • Mouth pipetting is prohibited. Mechanical pipetting aids should be used instead.
      • All biohazardous materials should be pipetted in a biosafety cabinet if possible.
      • Cotton-plugged pipettes should be used.
      • Biohazardous materials must never be forcibly discharged from pipettes. "To deliver" pipettes should be used instead of pipettes requiring blowout.
      • To avoid splashing, biohazardous material should be dispensed from a pipette by allowing it to run down the receiving container wall.
      • After using reusable pipettes, they should be placed horizontally in a pan filled with enough liquid disinfectant to completely cover them, and the entire pan should be autoclaved before cleaning the pipette for reuse.
      • When working in a biosafety cabinet, all waste and/or disinfecting containers must be kept inside the cabinet while they are being used.

      EH&S is responsible for calibrating portable survey instruments at Iowa State University. When the instrument is due for calibration, an EH&S staff member will inspect, inventory, and calibrate the meter. A calibration sticker is affixed to the instrument, indicating the calibration date, when the next calibration is due, and the name of the calibrator. However, lab personnel must ensure they use a meter with current calibration. Do not use a meter not calibrated within the last 12 months. Call EH&S at (515) 294-5359.

      Radiation detection instruments at Iowa State

      Handheld/portable instruments

      The Geiger-Mueller (GM) detector is a common portable instrument for a general laboratory radioactive material survey.

      • GM detectors can detect alpha, beta, and gamma radiation.  However, this instrument is limited by its ineffectiveness in detecting lower energy beta and gamma emitters.
      • The end-window or pancake Geiger-Mueller is a great instrument for detecting medium- to high-energy beta emitters, such as Phosphorus-32, Phosphorus-33, Chlorine-36, or Calcium-45.
      • Due to its poor efficiency in detecting some kinds of radiation, a Geiger-Mueller instrument is ineffective for detecting low-energy beta emitters, such as Hydrogen-3, Carbon-14, or Sulfur-35.  It is also ineffective for low-energy gamma emitters, such as Iodine-125 or Iodine-131.

      Open the Pre-operations Check of Radiation Detection Meters for Research Laboratories (PDF).

      Fixed instruments

      The NaI Scintillation detector is another type of portable detector for general laboratory radioactive material surveys.

      • NaI detectors are capable of detecting low-energy gamma radiation.
      • The NaI is a great instrument for detecting low-energy gamma emitters, such as Chromium-51, Iodine-125, Iodine-131, or Iron-59.
      • Due to its poor efficiency for detecting some kinds of radiation, a NaI detector instrument is not effective for detecting beat emitters, such as Hydrogen-3, Carbon-14, Phosphorus-32, Phosphorus-33, Chlorine-36, or Sulfur-35. ​

      Open the Calibration/Normalization of Liquid Scintillation Counters Procedure (PDF).

      Principal Investigators are ultimately responsible for the safe use of X-ray equipment and must ensure that all personnel using the equipment have up-to-date safety and device-specific training. The requirements for using X-ray equipment on campus are in the Radioactive Materials Safety Manual (PDF) and the X-Ray Safety Manual (PDF).

      For general x-ray information or to register an electron microscope or x-ray unit, contact EH&S at (515) 294-5359 or


      Principal Investigators must receive specific authorization from EH&S to use radiation-producing equipment on campus. EH&S conducts an annual inventory and inspection of the radiation-producing equipment and submits the required registration information to the Iowa Department of Health and Human Services.

      Visit the Radiation-producing/X-ray Devices Authorization page for more details.