The goal of occupational health practice is to protect the health of workers by
preventing diseases and injuries from occurring. When work activities are anticipated,
recognized, or found during an investigation to involve risks to workers' health,
preventive measures should be taken to control hazardous exposures in the workplace.
Respirators are often used to control inhalational exposures to hazardous airborne
contaminants, including infectious agents. Of the three methods available for selecting a
respirator, the expert opinion method is used most frequently to recommend respirators for
controlling exposures to infectious agents. The size of the particles comprising an
infectious aerosol has received particular attention relating to the selection of
respiratory protection for healthcare workers. Conflicting meanings of the term “droplet”
are central to this issue and may be partly responsible for confusion concerning the
particle sizes that surgical masks are unlikely to protect against. Although workers
caring for patients with contagious respiratory infections are at risk of exposure to
large-particle droplets greater than 100 micrometers in diameter, their risks of
inhalational exposure to infectious particles are likely to be predominantly to an aerosol
consisting of a mixture of evaporating droplets and droplet nuclei that remain suspended
in room air for prolonged periods. Because surgical masks are intended to be used only as
barriers against large-particle droplets, only respirators certified by the National
Institute for Occupational Safety and Health should be used as part of a strategy for
protecting workers against inhalational exposures to infectious aerosols. The issues
outlined in this paper are focused on workers in healthcare settings, but also apply in
other settings where workers may be exposed to infectious aerosols.
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