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Environmental Infection Prevention and Control in Oral Healthcare Settings

Course Number: 363


Aerosols are airborne particles generated both by humans and from environmental sources that may contain viable pathogens.1 Droplets greater than 5 µm are generated when a person coughs or sneezes, or when water is converted to a fine mist by medical/dental devices such as high-speed handpieces and ultrasonic instruments).1 Droplets may contain infectious pathogens, but they tend to quickly settle out from air so that any risk of disease transmission is generally limited to within 3 feet of the source.1

While pathogens in droplets are transmitted primarily by inhalation of droplets in close proximity to the source, transmission may also result from physical transfer of pathogens from a source contaminated with aerosols that have settled out from the air.1 Common pathogens spread by droplets include the influenza virus, rhinovirus, adenovirus, respiratory syncytial virus, and gram-positive cocci (e.g., Staphylococcus aureus and group A beta-hemolytic streptococci).1,2

Droplet nuclei are the residuals of droplets that, while suspended in air, dry out and produce particles ranging in size from 1-5 µm.1 Droplet nuclei can be transported beyond 3 feet of the source and remain suspended in air indefinitely in a dry, cool atmosphere.1 Pathogens can be transmitted by inhalation of droplet nuclei or contact with contaminated objects.1 Common pathogens spread by droplet nuclei include Mycobacterium tuberculosis (MBT), and the varicella zoster and measles viruses.1

Lasers and electrosurgical units release laser plumes or surgical smoke containing gases, tissue debris, and aerosolized infectious agents such as the human papilloma virus, HIV, coagulase-negative StreptococcusCorynebacterium spp., and Neisseria spp.1,2 Although the presence of pathogens in laser plumes or surgical smoke may not cause disease if the normal mode of transmission is not airborne, laser plumes and surgical smoke are considered potential health hazards.1,2

The presence of aerosolized allergens, derived primarily from latex gloves, carpeting, and cloth furnishings, must also be considered.1,2 Exposure to aerosolized allergens can cause urticaria, asthma, allergic rhinitis, conjunctivitis, angioedema, and rarely anaphylaxis. Because cornstarch/latex protein particles become airborne during the donning, use, and removal of gloves; in 2016 the FDA banned all powdered surgeon’s gloves because of unreasonable and substantial risk of allergic reactions.3