Aerosol Transmissible Diseases

To protect human health, respiratory protection is required for diseases that are transmitted by airborne particles. These diseases are called aerosol transmissible diseases (ATDs). An ATD is an infectious disease that can be transmitted to a person who inhales aerosol that contains particles of the disease. Aerosols are a gaseous mass of solid or liquid particles suspended in the air. Diseases/pathogens contained in the aerosols may be in the form of a virus, bacteria, or other microorganisms. The Cal/OSHA ATD standard (Title 8 CCR Section 5199, Appendix A) classifies these diseases/pathogens into two categories, as follows:

• Diseases/pathogens (AirID) that require airborne infection isolation (AII).
• Diseases/pathogens that require droplet precaution

In Appendix D of the ATD standard, Cal/OSHA establishes a separate list of pathogens that may be transmitted by laboratory aerosols. Employers of laboratory facilities must protect their workers from the diseases/pathogens on this list. This list includes many of the diseases and pathogens on the lists in Appendix A, for example, tuberculosis, typhoid fever, or meningitis. A link to Appendix D can be found in the additional resources section at the end of this course.

To learn more about Healthcare Respiratory Protection visit our Cal/OSHA Healthcare Respiratory Protection Safety Online Training web page.