Pneumonia is an infection that causes inflammation and fluid buildup in one or both lungs. Whether pneumonia requires airborne or droplet precautions depends entirely on the specific germ responsible for the infection. Different microbes have distinct biological characteristics that determine how they spread from person to person. Determining the causative agent is the first step in applying the correct infection control protocol to prevent further transmission.
Defining Droplet Versus Airborne Transmission
The distinction between droplet and airborne transmission is based primarily on the size of the respiratory particles that carry the infectious agent. Droplets are relatively large particles, generally considered to be five micrometers (\(\mu\)m) or greater in diameter. These larger droplets are expelled when an infected person coughs, sneezes, or talks, causing them to fall quickly to the ground or surfaces, typically traveling less than six feet before settling.
Airborne transmission involves much smaller particles, often referred to as droplet nuclei, which are less than five \(\mu\)m in size. These tiny particles are formed when larger droplets rapidly evaporate, leaving the infectious agent suspended in the air. Due to their minute size and light weight, these aerosols can remain suspended for extended periods and may travel long distances on air currents.
Most Common Pneumonia Requires Droplet Measures
The vast majority of cases, known as Community-Acquired Pneumonia (CAP), spread through the droplet route. Common bacterial causes, such as Streptococcus pneumoniae, and typical viral causes, like influenza, are transmitted in larger respiratory droplets. These pathogens are unable to survive the rapid evaporation process necessary to become true airborne particles, meaning standard infection control involves droplet precautions.
Droplet precautions are designed to interrupt the transmission of these larger particles that travel short distances. This protocol typically involves placing the patient in a private room to limit close contact with others. Any person entering the patient’s immediate space, generally within a 3 to 6-foot radius, is required to wear a surgical mask to protect the mucous membranes. The patient may also be asked to wear a surgical mask when leaving the room for medically necessary procedures.
Specific Pathogens Requiring Airborne Isolation
While most pneumonia is droplet-spread, a few specific pathogens that cause inflammation in the lungs are small enough to be aerosolized and require airborne precautions. The most common example is Mycobacterium tuberculosis, which causes tuberculosis (TB). Other highly contagious viral illnesses, such as Measles and Varicella (chickenpox), are also spread via the airborne route. These agents can linger in the air and travel beyond the six-foot range, making standard droplet measures ineffective.
Airborne precautions require the patient to be placed in a specialized room known as an Airborne Infection Isolation Room (AIIR). This room uses a negative pressure ventilation system to ensure air flows inward from the hallway, preventing contaminated air from escaping into other areas of the facility. The air inside the room is then exhausted safely to the outside or passed through a High-Efficiency Particulate Air (HEPA) filter. Healthcare personnel entering an AIIR must wear a fit-tested N95 respirator mask, which is designed to filter out at least 95% of airborne particles.
Everyday Hygiene and Prevention Strategies
Foundational public health measures remain the most effective tool for reducing the spread of all respiratory illnesses. Frequent and thorough hand hygiene is paramount, involving washing hands with soap and water for at least 20 seconds, especially after coughing or being in public spaces. This action disrupts the contact route of transmission, where germs are transferred from surfaces or hands to the face.
Proper respiratory etiquette significantly reduces the quantity of infectious particles released into the air. Individuals should cover their mouth and nose with a tissue when they cough or sneeze, or use the inside of their elbow if a tissue is unavailable, disposing of the tissue and cleaning their hands afterward. Staying current with recommended immunizations, particularly the influenza and pneumococcal vaccines, offers protection against common causes of pneumonia.