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Aerosolization


OSHA Section 9 - IX comments:
  • "Although there has been concern about potential infectivity of aerosols generated by dental, medical and laboratory equipment, HBV has not been detected in such aerosols, and risk is posed primarily by large particles of 'spatter' that travel only short distance.(Tr 9/14/89,p.21)"
  • "Aerosols are solid or liquid particles, ranging in size from submicrometer to multimicrometer, which are suspended in a gas.  This suspension can last from a few seconds to a day or more." p.50
  • "The term 'aerosolization'...has been replaced with 'generation of droplets.'" OSHA Section 9 XI
  • "...There has been no documented cases in the literature...of HIV transmission via aerosols..."
  • "...To the best of our knowledge...there have been no cases."
  • "...Aerosols are not known to present a risk of transmission of blood borne pathogens...Therefore, use of respirators for protection against blood borne pathogens is not recommended.p.50
  • "...The current opinion of experts is that, while aerosol transmission is a theoretical possibility, it does not contribute measurably to occupational transmission..."
  • "...There are no known instances...nor are other instances known in which airborne particles containing bloodborne pathogens have presented a risk to health care workers."p.50
  • "CDC/NIOSH...Aerosols are not known to present a risk of transmission of bloodborne pathogens in the healthcare environment.  There are no known instances...""
  • "aerosol" should not be used in the same context as splatters and splashes(Ex 20-1157)p.51

OSHA intends a distinction between "droplets" and "aerosols"
to make it clear that "droplets" "spatters" "splashes" (such as produced by power saws and drills) are of concern, not  'aerosolization' (as produced by ultrasonics), neither by airborne respiratory transmission or as evidence of contamination of environmental surfaces by aerosolization.

"Splattering of blood onto skin or mucous membranes of the face and upper respiratory tract against large droplet splattering is needed. ...glasses, goggles, face shields, and surgical masks...as appropriate to the task being performed, can provide that protection."OpCit p.51

Pseudo-scientists put some "marker-dye" in an ultrasonic and observed the "marker dye" was aerosolized and deposited on surfaces away from the ultrasonic.  They concluded that covering that ultrasonics was necessary to limit the spread for pathogens and protect the worker. Their experiment was faulty and their conclusions were false.

  • The emphasis by OSHA is to encourage the establishment of procedures that prevent the initial problem before focusing on protection.
    "Paragraph (d)(2)(xi) requires that all procedures involving blood or other potentially infectious materials shall be performed in such a manner as to minimize splashing, spattering, and generation of droplets of these substance . . . will also reduce contamination of surfaces e.g., benchtops, instruments) in the general work area"
     
  • "Assuming a 'worst case' of a single virion infectivity and knowing the capability of minute aeosols to remain suspended in air and therefore spread widely throught the facility, respiratory protection would be necessary for essentially every person within the facility. However, if such a situation were true, the Agency would expect seroconversion rates to be drastically increase among those exposed; but this does not appear to be the case." Summary, p.52"

"The hierarchy of controls provision, paragraph (d)(2)(i), of this standard requires employers to implement engineering controls and work practices prior to relying on personal protective equipment for protecting employees against exposure" OSHA