INSIGHTS FROM INDUSTRY
DEMYSTIFYING PORTABLE AIR PURIFIERS A GUIDE FOR YOUR NEXT PURCHASE
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ir purifiers (air scrubbers or portable HEPA filters) have attracted significant attention with hospitals, aged care facilities, office-based practices such as GPs and schools purchasing units to reduce transmission of harmful pathogens such as COVID-19. But do they work? Will they protect our patients and healthcare workers from airborne viruses, and what are the considerations when choosing an air purifier? An observational study from a large tertiary hospital in Melbourne provides some insights. The study traced the airflow, transmission and clearance of aerosolised particles within the clinical spaces to examine the impact of portable air purifiers. Employing glycerin-based aerosol smoke as a surrogate for respiratory aerosols, researchers measured the movement from a single patient room within one ward. Their baseline measurement demonstrated the rapid travel of aerosols from the patient room into both the corridor and nurse’s station, however, the addition of two portable HEPA air purifiers to a single patient room, with the door closed, resulted in 99 per cent of aerosols being cleared within 5.5 minutes, equivalent to a 67 per cent reduction compared with no air cleaners.
Initial considerations
Features and functions to consider when choosing an appropriate air filter can be confusing, as procurement and infection prevention teams come to terms with the language and norms associated with air purification systems. Ultimately, the filtering efficiency will depend on the air purifier’s power and filtering capacity, and the space volume in the room. However, many other aspects warrant consideration.
Filters
Ensure the unit contains genuine HEPA filters and not HEPAlike filters. HEPA stands for High Efficiency Particulate Air. HEPA H13 to H14 are considered medical-grade quality, filtering a minimum of 99.97 per cent of particles down to 0.3 microns in diameter. The addition of pre-filters protect and prolong the life of the HEPA filters, and carbon or charcoal filters reduce unwanted
Air purifiers can make a big difference to air quality. odours and Volatile Organic Compounds (VOCs). Filters must be changed according to facility infection prevention policies, but an air purifier unit with a Change of Filter notification system will aid timely removal and replacement.
Clean Air Delivery Rate (CADR)
Expressed in cubic metres per hour (m3/hr), CADR is an industry standard measure of the air volume that the air purifier can clean. The higher the number, the more effective the filtration. An air purifier with high and variable flow rate options will ensure adequate air changes per hour.
Particle sensor
Built-in particle or air quality sensors analyse air quality within the room. The amount of PM2.5 in the air is a key indicator of air quality. PM stands for particulate matter, and 2.5 refers to size (2.5 micrometres). A PM2.5 value of less than 100 is very good, and over 200 is not good. As the unit cleans the air, the level of improvement can be observed using a numerical or colour-coded monitor function. Units with an auto-mode will adjust the speed of the motor automatically according to air quality. Continued on page 76
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