Getting to know various Air Purifiers
There is ample research backing the fact that indoor air quality is as bad, if not worse, than the outdoor air quality. This means that having an air purifier inside our homes has become a necessity, especially if we want to get rid of unpleasant odour, trap dust particles and airborne allergens released by pets. But you can always get your indoor air tested to be sure.
Air purifiers can also be used to neutralize smoke and avoid various small airborne particles including pollen, mold spores and bacteria that float around in the indoor air.
Air purifiers become even more important when we want to ensure that nobody else in the house becomes ill when someone in the family is sick with a highly infectious disease.
The coronavirus pandemic has us worried even more since it is common knowledge that the novel coronavirus spreads via droplets expelled from the body through coughing, talking, and breathing. Research suggests that while most droplets fall to the ground, a fraction of them remain suspended in the air for longer.
Although it would seem that air purifiers can reduce the transmission of this virus, indoor air quality expert and Professor of civil engineering at the University of Toronto, Jeffrey Siegel states that we don’t have any direct evidence of the fact yet.
A researcher who has worked on portable air purifiers, Siegel also states that we can infer the effectiveness of purifiers and filters using what we already know, especially for similar viruses like SARS.
During the SARS outbreak in 2003, the Hong Kong Hospital Authority recommended that the hospitals use portable air purifiers with HEPA filters to help reduce transmission among healthcare workers in healthcare facilities that lacked isolation wards. The Centre for Disease Prevention and Control, U.S., also recommended the use of HEPA purifiers during the outbreak to help reduce viral concentrations.
According to Linsey Marr, an environmental engineer and Professor at Virginia Tech, any air purifier that removes viruses from air reduces the viral concentrations and any chances of exposure to the virus. This means that air purifiers can remove coronavirus particles from the air and prevent us from getting infected with COVID-19 and other airborne infections.
At present, there are various air purifiers, each of which employs unique technology to filter air and fulfills different purposes. To help you understand what air purifiers do, how they work and most of all decide on a type of air purifier you should buy, we have put together a list of the available air purifiers along with their efficiency, effectiveness, technology and the testing standards they have been subjected to.
Various Air Purifiers in Market
The Nanomax filters by IQ Air are said to have five times more the surface area of a conventional pleated air filter, which increases the filtering fine and ultrafine particles up to 95%. The filters have five different filtration effects (Straining, Impingement, Interception, Electrostatic and Diffusion effects), which distinguish these filters from other conventional HVAC filters. These effects help in increased airflow and better filter loading, widening the replacement intervals and also reducing costs. It is said to exceed MERV 16 following ASHRAE 52.2.
The Novaerus Nanostrike technology uses a low energy patented plasma that is highly destructive to the microorganisms entering its field. The Nanostrike attacks the pathogens by perforating the cell wall, destroying the DNA and protein within it. Gradually the cell bursts open due to osmotic pressure, without giving any opportunity to the microbe to develop antimicrobial resistance.
The plasma produces no harmful by-products and requires no maintenance, making it perfectly safe for patients and staff. It is independently tested by different laboratories and validated by NASA.
The powerful combination of the NanoStrike technology and a triple-stage Camfil filter system that Novaerus Defend 1050 uses for air disinfection and particle removal makes it powerful. The Novaerus Defend 1050 is also tested to EN 1822 and ISO 29463 standards.[1,5]
Camfil: EPA, HEPA and ULPA Filters
Camfil’s clean air solutions for everyone. They help biomanufacturing firms, research labs and the healthcare sector in protecting sensitive advanced manufacturing processes, preventing microbiological contamination and eliminating infectious airborne contaminants. Their filters are tested to EN 1822 and ISO 29463 standards. Camfil’s filters use molecular filtration to remove molecules, gases and vapours from the air. All molecular products from Camfil undergo testing according to ISO 10121 or ASHRAE 145.2.
Airgle provides a technology equipped with cHEPA, activated carbon and PCO filtration that remove airborne pollutants, such as dust particles, odours, smoke, bacteria, viruses, allergens and VOCs.
The patented Titanium Pro Module kills up to 99.97% of bacteria and viruses with PCO technology. When UV light rays combine with a TiO2 coated filter, highly reactive hydroxyl radicals and superoxide ions are generated. These ions combine with other elements in the air, such as bacteria and VOCs (harmful pollutants such as formaldehyde and ammonia).
The chemical reaction between the super-charged ion and the pollutant, effectively oxidises the pollutant and breaks the pollutant down into harmless carbon dioxide and water molecules, making the air devoid of VOCs.
In an independent test performed by the Association of Home Appliance Manufacturers (AHAM AC-1-2020, AHAM AC-1-2013, AHAM AC-1-2006 for CADR of dust smoke, and pollen), the AG800 achieved CADR ratings that are among the highest in the purifier industry.
Radon in the air has been associated with lung cancer risks and the Airgle AG600S takes into consideration this concern. It has been equipped with a premium radon removal filter and an antimicrobial cHEPA filter that has a 99.999% efficiency to ensure you breathe in air that has no contaminants. The Airgle AG25 is another fantastic option which ensures the customer’s comfort and ease by employing auto-cleaning technology and auto temperature control settings.
The Dyson Pure Hot+Cool air purifier goes beyond standard test conditions, automatically sensing particles and gases, capturing 99.95% of ultrafine particles as small as 0.1 microns, and projecting and circulating purified air throughout the room using Air Multiplier technology with 350º oscillation. To remove gases as well as ultrafine particles Dyson purifiers use activated carbon filters and sealed HEPA filters, which capture 99.95% of all allergens and pollutants.
The purifiers are tested using standard purification and heating performance tests based on AHAM AC1-2015 which defines purifier performance in a specified test chamber, based only on cleaning efficiency rates and IEC 60675. Dyson goes beyond these, by testing filtration efficiency using EN1822.
The Dyson purifiers undergo Dyson POLAR test which involves testing in an 81m3 real room space, equipped with 9 sensors continuously monitoring how a room is purified by removing 5 particles and 11 gases. 
Blueair offers a unique, patient filtration technology to its customers. Air purifiers from Blueair use a combination of mechanical and electrostatic filtration called the HEPASilent technology, which gives 99-100% efficiency in capturing particles of all sizes.
The Blueair technology uses ionizers and mechanical filters to filter air. Any particles from the incoming air are charged as they move past the ionizers and these are then captured by the mechanical filters, cleaning the air. Another advantage of the Blueair is that it filters air without emitting ozone as a by-product. The HEPASilent system uses special design filters with less densely packed fibres that do not reduce airflow, ensuring Blueair units achieve high CADR.
All Blueair cleansers have ENERGY STAR certifications as all their units meet the lower energy consumption and running cost National Standards put forward by the U.S. Environmental Protection Agency and the Department of Energy. Blueair also gets all its units certified from the most stringent standards for testing ozone as a by-product from air purifiers, the California Air Resource Board.
XENEX LightStrike employs a patented Pulsed Xenon UV light system to produce UV across the entire germicidal spectrum (200-315 nm) to inactivate microorganisms in the air. Not only does the system inactivate the pathogens at the wavelengths where they are most susceptible, but it also prevents the acquisition of hospital-acquired infections due to surface contamination.
Most UV lamps that purify the air use the continuous single spectrum UV lamps, but XENEX LightStrike uses the pulsed UV, which is characterized by bursts of high-intensity UV. These pulses of UV do not damage any expensive equipment present in most hospitals, hotels and other environments.
The XENEX PX-UV system, which also uses pulsed UV light for purification, is tested for its efficiency in various facilities according to CDC Guidelines.
Note: ASHRAE:185.1 is used in general to test the UVC lights that are used in air ducts to inactivate microorganisms, and ISO 29464:2017 is applicable to air filters and air cleaners (both particulate and gas phase) used in inhabited indoor spaces for general ventilation. It is also applicable to air inlet filters for UV-C germicidal devices.
Atlanta Healthcare air purifiers ensure that the air you breathe in is devoid of any toxic air pollutants (formaldehyde, benzene, ammonia, VOC, etc.), contaminants, chemical fumes, smoke and pathogenic microorganisms.
It is a known fact that any single filtration technology isn’t capable of eradicating all pollutants in the air. This is why, to ensure effective purification, multi-stage filtration technology which includes Prefilter-H13HEPA-ESP-Molocular sieve filters- carbon filters-cold catalyst filters-fibre filter-photo catalyst-UV-Ionizer is used.
The iCluster technology from Atlanta Healthcare also uses synchronized multi-stage intelligent filtration to provide pure air, devoid of all pollutants.
Airinspace uses HEPA-MD technology which is a combination of HEPA filtration and irreversible microbial destruction by exposure to high electric fields and oxidizing species in cold plasma chambers. This helps capture the charged particles using plasmerisation modules in an electrically active collection medium by continuously bombarding biological residues with oxidising species.
The presence of catalytic converters helps eliminate volatile molecular compounds by converting charged particles into inert molecules. The activated carbon is responsible for absorbing bad odours. Their devices are tested in ISO 13485 and ISO 9001 Certified laboratories.
SHARP air purifiers
SHARP air purifiers use a combination of two technologies, referred to as Active Plasma Cluster technology and Passive filtration, to remove contaminants from indoor air.
The active plasma cluster technology generates clouds of ions by electrical discharges and releases Hydrogen (+) and Oxygen (-) ions surrounded by water molecules in the air. Unlike Ionizers, this technology produces both positive and negative ions using water vapour in the air, without emission of ozone. These ions attach to pollutants and break down their surface before returning to the air as water vapour.
The air also passes through passive filtration before returning to the room which involves high-performance carbon and HEPA filters. The filters capture 99.97% of dust particles of 0.3 microns, 99.85 % removal of dust mite faeces, allergens and any PM 2.5 present in the air. SHARP air purifiers are tested to EN 1822 standard.
Philips air purifiers use Vitashield technology with Nano Protect HEPA Filters in combination with prefilter and activated carbon filters. AeraSense, a sensing technology that accurately identifies fine particles smaller than PM2.5, is commonly used in Philips purifiers and gives them an edge. This means that the purifiers can identify and remove the most common indoor airborne allergens.
The VitaShield has a clean air delivery rate (CADR) up to 260 m3/hr, which can be attributed to its aerodynamic design and NanoProtect Pro Filter.
Philips air purifiers also remove 99.97% of air pollutants in just 6 minutes and are tested with NaCl aerosol by iUTA according to DIN71460-1, NRCC-54013 standard using cigarette smoke and CADR according to GB/T18801-2015.
The Philips purifiers are Airmid Certified.
Airmid specialises in testing portable air cleaning devices using validated protocols in their 28.5m3, 30m3 and 3 m3 environmental test chambers which are designed according to ASHRAE 52.2 and ASTM F1471-09 standards.
In general, the lesser the dust, the lesser the chances for bacteria and viruses to attach themselves to, which, in turn, reduces their mobility and decreases the chances of these damaging particles entering our respiratory system – thereby protecting us from infections. However, it should be noted that air purifiers and air cleaners are only a preventive action against the spread of infections.
- C. Jinadatha et al. / American Journal of Infection Control 43 (2015) 415-7, “Can Pulsed Xenon Ultraviolet light systems disinfect aerobic bacteria in the absence of manual disinfection”