In hospitals, managing air pressure within certain rooms is a key aspect of infection control. Positive and negative room pressure systems are commonly used to influence the direction of airflow in areas that require special attention to air quality. These systems support strategies aimed at limiting the movement of airborne contaminants in healthcare settings.
What are Positive and Negative Room Pressures?
Room pressure in hospitals refers to the difference in air pressure between one space and an adjacent area. Positive and negative room pressures serve different purposes depending on the type of room and the level of contamination risk.
- Positive pressure occurs when the air pressure inside a room is higher than the pressure in surrounding areas, causing air to flow outward. This approach is often used in rooms that require a cleaner environment compared to adjacent spaces.
- Negative pressure, in contrast, involves lower pressure inside the room than outside, which draws air inward. This method is typically used in spaces intended to isolate contaminants within the room.
Positive Room Pressure: Directing Air Outward
Positive pressure rooms are designed to direct clean, filtered air outward into adjacent spaces, which may help limit the entry of airborne particles such as dust, microorganisms, and viruses. These rooms are commonly used in areas where controlling airborne exposure is a priority, including:- Operating rooms: These environments often use positive pressure to help maintain directional airflow outward during procedures requiring sterile conditions.
- Intensive care units (ICUs): Positive pressure may be used to support airflow strategies in spaces where patients are vulnerable to environmental contaminants.
- Pharmaceutical compounding areas: Where medications are prepared, clean air practices—including the use of positive pressure—are often implemented to help manage air quality.
Negative Room Pressure: Containing Airborne Pathogens
Negative pressure rooms are commonly used to isolate individuals with known or suspected airborne infectious diseases. These rooms help direct airflow inward to limit the release of airborne particles into surrounding areas. Examples of when negative pressure rooms may be used include:- Tuberculosis (TB): To help contain particles associated with TB transmission.
- COVID-19: Widely used during the pandemic as part of infection control protocols.
- Measles and chickenpox: Airborne viruses such as these are often managed using isolation rooms with negative pressure.
- In these rooms, air is pulled inward and then filtered—typically through HEPA filters—before being exhausted outside or recirculated safely. This approach supports containment practices by reducing the outward flow of potentially contaminated air.
Supporting Airborne Infection Control Strategies
While positive and negative room pressures serve different functions, both are widely used to support hospital infection control strategies. These airflow practices aim to:- Manage patient exposure: Using pressure differentials to influence the movement of airborne particles around patients in high-risk areas.
- Support containment efforts: Using airflow directionality to limit the spread of contaminants from isolation areas.
- Assist in occupational safety: Controlling airflow to reduce potential exposure for healthcare workers in specific environments.
- Meet standards and guidelines: Many hospitals implement room pressure controls to align with recommendations from organizations such as the CDC and ASHRAE.
Balancing Hospital Air Pressure Systems
Balancing these systems requires careful calibration by hospital facility teams. HVAC systems must be maintained to help ensure air pressure stays within designated ranges, and many facilities use continuous monitoring to track performance. Inconsistent pressure levels can disrupt airflow patterns, potentially affecting broader infection control efforts.Conclusion
Positive and negative room pressures are widely used in hospital environments as part of broader air quality and infection control programs. Positive pressure supports the flow of filtered air into areas such as operating rooms and ICUs, while negative pressure is applied in isolation rooms to draw air inward and reduce the spread of airborne contaminants. Together, these systems contribute to managing airborne risks in critical healthcare environments.
Learn more about Hospital Room Pressure Monitoring and Controls
References
- Centers for Disease Control and Prevention (CDC). "Guidelines for Environmental Infection Control in Health-Care Facilities." 2003
- American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). "HVAC Design Manual for Hospitals and Clinics." 2013
- World Health Organization (WHO). "Infection Prevention and Control of Epidemic- and Pandemic-Prone Acute Respiratory Infections in Health Care." 2014