Effectiveness of air purifiers in intensive care units: an intervention study

Background: Effective design and operation of intensive care unit (ICU) ventilation systems is important to prevent hospital-acquired infections. Air purifiers may contribute.

Aims: To detect the number and types of micro-organisms present in the air and on high-touch surfaces in ICUs, and to evaluate the effectiveness of air purifiers in reducing the microbial load and thus the rate of nosocomial infections in ICUs.

Method: This intervention study was conducted in two similar ICUs between May to November 2020. Novaerus air purifiers were located in the intervention ICU for 2 months. Routine cleaning procedures and high-efficiency particulate air filtration continued in the control ICU as well as in the intervention ICU. After 2 months, the air purifiers were moved to the other ICU for the next 2 months to reduce any possible bias in the results. Air and surface samples were evaluated.

Findings: Evaluation of changes in the intervention ICU over time revealed a significantly lower colony concentration in the air and on surfaces on Day 60 compared with Day 1 (P_air<0.001 and P_surface<0.001). There was a significant positive correlation between the number of colonies detected and the rate of hospital-acquired infections in the intervention ICU (r=0.406, P=0.049) and in the control ICU (r=0.698, P=0.001).

Conclusion: Using air purifiers in addition to heating, ventilation and air conditioning systems in hospitals may be an effective way to reduce the microbial load in the air and on surfaces, and thus hospital-acquired infections.