Airborne transmission

Airborne transmission

Illustration of aerosol transmission

Airborne precautions poster

Video on reducing virus transmission indoors

Airborne transmission refers to the spread of infectious agents caused by the dissemination of aerosols that remain infectious when suspended in air over long distances and time. This mode of transmission is significant in the spread of various infectious diseases, including tuberculosis, measles, and COVID-19.

Mechanism of transmission

Airborne transmission occurs when infectious agents are carried by dust or droplet nuclei suspended in the air. These droplet nuclei are small particles, typically less than 5 micrometers in diameter, that can remain airborne for extended periods and travel long distances. When inhaled, these particles can deposit in the respiratory tract, leading to infection.

Aerosol generation

Aerosols can be generated by various activities, including coughing, sneezing, talking, and certain medical procedures. The size and concentration of aerosols can vary depending on the activity and environmental conditions.

Environmental factors

Several environmental factors influence airborne transmission, including:

• Ventilation: Adequate ventilation can dilute and remove infectious aerosols from indoor environments.
• Humidity: Low humidity can increase the suspension time of aerosols in the air.
• Temperature: Temperature can affect the stability and viability of infectious agents in aerosols.

Diseases transmitted by airborne route

Several diseases are known to be transmitted via the airborne route, including:

• Tuberculosis
• Measles
• Varicella (chickenpox)
• COVID-19

Prevention and control

Preventing airborne transmission involves a combination of strategies:

Airborne precautions

Airborne precautions are specific infection control measures used to prevent the spread of diseases transmitted by the airborne route. These include:

• Use of N95 respirators or higher-level personal protective equipment (PPE) by healthcare workers.
• Isolation of patients in rooms with negative pressure ventilation.
• Limiting the movement of patients outside their rooms.

Environmental controls

Improving ventilation and air filtration in indoor spaces can reduce the concentration of infectious aerosols. The use of HEPA filters and ultraviolet germicidal irradiation (UVGI) are effective methods to inactivate airborne pathogens.

Related pages

• Droplet transmission
• Infection control
• Personal protective equipment
• Ventilation (architecture)