6.1  Introduction

6.2  Risks

6.3  Aerosol Production

6.4  Minimizing Aerosol Production

6.1       Introduction

The word "aerosol" refers to the physical state of liquid or solid particles suspended in air.  The production of aerosols while handling infectious agents may present a serious risk of exposure.


6.2       Risks

Aerosol particles one to five microns in size presents the greatest hazard to the laboratory worker because:

         Small particles readily penetrate and remain in the respiratory tract if inhaled.

         Many routine laboratory procedures create aerosols in this size range.

         They may remain suspended in air for long periods of time. 

Aerosols can settle on equipment normally considered to be clean.  Skin contamination from aerosols or from handling contaminated equipment may result in infection through ingestion, mucosal membrane contact, or skin abrasions.  It is also possible for aerosol particles to be spread by the building ventilation system. 

Risks associated with aerosols can be reduced or eliminated by the use of good technique in a biological safety cabinet.


6.3       Aerosol Production

Aerosols may be produced in the use of:




         magnetic stirrer



         vortex mixer

         syringe and needle

         freeze-dried sample

         vacuum-sealed ampoule

         grinder, mortar, and pestle

         test tubes and culture tubes

         heated inoculating loop

         separatory funnel



6.4       Minimizing Aerosol Production

To reduce/minimize aerosol production:

         perform activities that may produce aerosols in a biological safety cabinet (preferred) or a chemical fume hood

         keep tubes stoppered when vortexing or centrifuging

         allow aerosols to settle for one to five minutes (BSL1/2) and five to ten minutes (BSL3/4) before opening centrifuge, blender, or tubes that have been mixed

         place a cloth soaked with disinfectant next to the work area to deactivate possible spills or droplets of biohazardous agents

         reconstitute or dilute contents of an ampule slowly

         when mixing two solutions, discharge the secondary fluid down the side of the container or as close as possible to the surface of the primary solution

         allow inoculating loop or needle to cool before touching biological specimens

         wrap with disinfectant-soaked gauze when:

            -removing the needle from the rubber stopper of a test tube or vial,

            -breaking the cap on an ampule,

            -removing stoppers or plugs from tubes, or

            -expelling air or surplus solution from a syringe

         if the safety cups and/or rotors are not gasketed, run them in the biological safety cabinet (BSL1/2); Open centrifuge cups/rotors in the biological safety cabinet (BSL3/4)  

Do not:

         mix a solution by flushing with a pipette or syringe;

         MOUTH pipette;

         use a hypodermic and syringe as a substitute for mechanical pipetting devices when transferring infectious fluids.