Every year, air pollution spikes after Diwali. It is typically around this time that people buy an air purifier to combat the rise in air pollution. And as we are amidst the pandemic, people naturally wonder whether an air purifier can offer much-needed protection against Covid-19. After all, many air purifiers do promise to capture particulate matter, bacteria and even viruses.
So, is it really effective? We talked with air quality and health experts to know about how air purifiers can help.
Air Purifier Efficiency
Air purifiers available in the market contain HEPA filters which capture particulate matter larger than 0.3 microns. The efficiency, however, depends on the grade of HEPA filter used. While H14 HEPA filter can capture 99.95% of all particles larger than 0.3 microns, an H10 HEPA filter captures only 85% of particles larger than 0.3 microns.
Brands like Dyson claim that their air purifiers can capture particulate matter as small as 0.1 microns. Their H13-A grade HEPA filter is made of 9m of borosilicate microfibers, pleated over 200 times. Also, by sealing filters, they ensure that the captured particles do not escape back to the surrounding.
But even then the most sophisticated air purifier does not provide protection against Coronavirus because the size of Covid-19 is smaller.
Researches show that the size of Covid-19 virus ranges from 60 to 140 nanometer (.06 to .12 microns). As you can see, even the most sophisticated air purifier that captures particles larger than 0.1 microns may leave out a large chunk of the viruses in the air.
Methods of Transmission
WHO says that the virus is transmitted through droplets generated when an infected person coughs, sneezes or speaks. And the size of these droplets is considered to be larger than 0.1 microns. But then, there is a higher risk of transmission as these particles could fall on surfaces due to gravity. In such a situation, air purifiers won’t have much of a role in curbing the transmission.
Jolene Caufield, a healthcare advisor at Healthy Howard says, “ Even advanced air purifying technology like Photoelectrochemical Oxidation (PECO) can’t exempt you from the risk of catching COVID-19 due to one root problem- physical contact transmission. At the end of the day, air purifiers, no matter how technically advanced, can’t hold a candle to hygienic practices as suggested by our healthcare experts.”
Photoelectrochemical Oxidation (PECO) Air Purifiers
PECO air purifiers are proven to have the technology to reduce circulating indoor allergens. It can destroy organic matter which is otherwise not trapped by a traditional filter.
The air purifier oxidizes the organic matter to destroy it. It is a technology patented by Molekule, a company based in the US. And the best part is that it doesn’t produce Ozone, a potential lung irritant, as a by-product.
In India, you have Sharp Air purifiers with plasmacluster air purifying technology, which is similar to PECO. It too doesn’t produce ozone as a by-product. Sharp even claims that it reduces airborne coronavirus particles in a controlled environment.
The plasmacluster technology emits hydrogen and oxygen ions through plasma discharge. These ions bond on to the proteins of bacteria, virus and other allergens to decompose them with its high oxidizing power. As it is more of an attacking mechanism rather than a capturing mechanism, the size of the filter or virus doesn’t matter.
Sharp claims that their plasmacluster technology cuts concentrations of novel coronavirus particles by about 90 per cent in an experiment jointly conducted with Nagasaki University and Shimane University.
Panasonic Corp. and Daikin Industries Ltd. have even claimed that their air purification technologies could inhibit the virus when attached to a surface as opposed to airborne particles that were so far being captured by air purifiers.
However, its efficiency in real-life scenario is yet to be proven, as it is highly doubtful whether it can cover the entire air in a given area without even leaving a cubic centimetre.
Though researches in a controlled environment have shown air purifiers to reduce the concentration of covid-19 in the air, it cannot provide the necessary protection against Covid-19. This is because a major source of transmission is through direct contact and via contaminated surfaces. Moreover, it is still not proven whether the air purifier can cover the entire air in an environment.