Tuberculosis (TB) requires airborne precautions, the strictest category of infection control. Unlike many infections that spread through large droplets or surface contact, TB bacteria travel in tiny particles called droplet nuclei that can float in the air for hours and travel throughout a room or building. This is why TB demands a specific set of protective measures that go well beyond standard hand hygiene and gloves.
Why TB Requires Airborne Precautions
When someone with active TB disease in the lungs or throat coughs, sneezes, speaks, or sings, they release microscopic particles into the air. These droplet nuclei are small enough to stay suspended and be inhaled deep into the lungs of anyone nearby. This makes TB fundamentally different from infections spread by larger respiratory droplets, which fall to the ground within a few feet. Because the particles linger, simply standing a few feet away from an infected person is not enough protection.
Airborne precautions are reserved for a small number of diseases that spread this way, including TB, measles, and chickenpox. For TB specifically, these precautions apply only to active TB disease. People with latent TB infection, where the bacteria are present but inactive, cannot spread TB to others and do not need respiratory isolation of any kind.
Airborne Infection Isolation Rooms
The cornerstone of TB precautions in a healthcare setting is the airborne infection isolation room (AIIR). These are single-patient rooms kept under negative pressure, meaning air flows into the room from the hallway rather than out of it. This prevents contaminated air from drifting into corridors and other patient areas. The room’s ventilation system filters and exhausts the air, and some facilities add ultraviolet germicidal lights to kill any remaining bacteria.
Patients with suspected or confirmed infectious TB stay in these rooms until they are no longer considered contagious. The standard criteria for ending isolation include at least two to three weeks of appropriate TB medication, visible clinical improvement, and three consecutive sputum samples that test negative for TB bacteria. If there is any concern about drug-resistant TB, isolation typically continues longer.
Respiratory Protection for Healthcare Workers
A surgical mask is not sufficient protection against TB. Healthcare workers entering an isolation room must wear at least an N95 respirator, which filters out 95% of airborne particles. This is a critical distinction: a standard surgical mask blocks large droplets but does not seal tightly enough to prevent inhaling the tiny droplet nuclei that carry TB.
N95 respirators must be fit-tested to ensure they form a proper seal around the wearer’s nose and mouth. Every time the respirator is put on, the wearer should perform a fit check, covering the front and inhaling to confirm that air is being pulled through the filter rather than leaking around the edges. For higher-risk procedures like bronchoscopy or sputum collection, facilities may require powered air-purifying respirators (PAPRs) that use a blower to push air through a high-efficiency filter and deliver it to a hood or helmet.
Masking the Patient
While healthcare workers wear respirators to protect themselves from inhaling TB, patients with active TB wear a standard surgical mask to reduce the number of droplet nuclei they release into the air. This distinction matters: the patient’s mask contains the source, while the worker’s respirator filters what gets through.
If a TB patient must leave the isolation room for any reason, such as a diagnostic test or transfer, they should wear a surgical mask for the entire time they are outside the room and follow cough etiquette, covering their mouth and nose when coughing or sneezing. Transport outside the isolation room is kept to a minimum.
Precautions During High-Risk Procedures
Certain medical procedures dramatically increase the amount of TB bacteria released into the air. Sputum induction, where a patient inhales a mist to help produce a deep cough sample, is one of the most common. These procedures must be performed either inside a local exhaust ventilation booth that captures the aerosol at its source or in a room that meets the same ventilation standards as a TB isolation room.
Staff in the room during the procedure must wear a properly fitted N95 respirator. If the patient is inside a functioning exhaust booth, staff standing outside it do not need respirators. Warning signs must be posted on the door of any room being used for sputum induction. After the procedure, the room needs time for its ventilation system to clear 99% of airborne particles before anyone enters without respiratory protection.
TB Precautions at Home
People diagnosed with active TB disease who are recovering at home also need to take precautions, particularly during the first weeks of treatment before medications reduce their infectiousness. Wearing a mask around other household members, staying home from work or school, and keeping living spaces well ventilated are the key measures. Opening windows and using fans to move air outdoors can substitute for the engineered ventilation systems found in hospitals.
Visitors, especially young children and anyone with a weakened immune system, should limit close contact during this period. Once the treating clinician confirms the patient is responding to medication and sputum tests show reduced or absent bacteria, these restrictions gradually ease.
Children and TB Precautions
Young children with TB are generally considered less infectious than adults. Their form of the disease typically involves a lower concentration of bacteria, and they usually lack the forceful cough needed to propel droplet nuclei into the air effectively. In practice, this means the adults around a child with TB (often the source of the child’s infection) may pose a greater transmission risk than the child does. Still, airborne precautions are applied in healthcare settings until infectiousness can be assessed, and any adult accompanying a child with TB should also be evaluated.