Techniques for Minimizing Aerosols

Using a Loop:

  • Use a cooled loop for insertion into a culture
  • Ensure the loop is completely closed
  • Use short loops: the shank should be no more than 6 cm long to avoid vibrations
  • Use a micro‐incinerator or pre‐sterilized plastic loops rather than flaming a loop in an open flame


  • Streak plates where the surface of the medium is smooth (i.e. avoid bubbles)


  • Use “to deliver” pipettes to avoid blowing out the last drop
  • Drain pipettes gently with the tip against the inner wall of the receiving vessel
  • Use pipettes with plugs to reduce contamination of the pipetting device
  • Work over an absorbent, plastic‐backed pad to avoid aerosol dispersion from drops falling on hard surfaces
  • Do not mix materials by alternate suction and expulsion through a pipette (use vortex mixer)


  • Use sealed safety cups and sealed rotors
  • Open cups inside a biosafety cabinet
  • Allow cups to sit prior to opening to allow aerosols to settle if no biosafety cabinet available

Blending and Homogenizing:

  • Use a laboratory blender with a tight‐fitting gasketed lid and leak‐proof bearings (domestic kitchen blenders leak and release aerosols)
  • Wait as long a s possible before opening the lid after mixing

Using needles and syringes:

  • When withdrawing a needle from a stoppered bottle, wrap the needle and bottle cap in a disinfectant‐soaked absorbent
  • Use syringes with a Luer lock connector
  • Dispose of needles directly into sharps container without further manipulation (needle‐cutting devices release aerosols)

Opening tubes:

  • Avoid using tubes with push‐in closures (when opened, the film of liquid trapped between tube and closure breaks and releases aerosols)
  • Use a vortex mixer instead of inverting tubes
  • Wait 30 seconds after shaking a tube before opening

Pouring infectious liquids:

  • Avoid pouring off supernatant – use pipettes instead
  • Pour infectious liquid waste through a funnel where the end is below the surface of the disinfectant in the discard container; pour disinfectant through the funnel after use

Opening ampoules of lyophilized cultures:

  • Avoid hasty opening by snapping the neck, which can lead to sudden inrush of air and dispersal of contents – instead make a file mark near the middle of the cotton plug and apply a red‐hot glass rod to crack the glass, allow time for air to seep into the ampoule and gently remove the top and plug
  • Add liquid for re‐suspension slowly to avoid frothing


  • Use plastic labware rather than glass (less likely to break which generates aerosols)


Source: Adapted from the Canadian Food Inspection Agency