As winter forces people to spend more time indoors, concerns about the novel coronavirus, Covid-19, are increasing. Covid is spread through droplets of moisture from the breathing and coughing of an infected person, and the risk of infection increases in confined spaces.
Air purifiers, sometimes referred to as “air scrubbers” are designed to take pollutants out of the air through your HVAC system. Many people are turning to them as a way of mitigating risk in indoor settings, but is that actually helpful? Before running out to buy a new air filter, here’s what you need to know.
Not all air purifiers are created equal. There are four major types of air purifier, and they handle removing pollutants in different ways. Here is a brief summary of each, and how they tackle unwanted air particles.
You probably already have an air filter in your HVAC system, which is a simple mesh that traps dirt, hair, and other particles in them. Unless you specifically bought a HEPA filter for it however, it is probably a low-MERV filter, which doesn’t catch very fine particles.
HEPA is made to remove 99.7% of particles, including those as small as 0.3 micron in diameter. As far as Covid-19 goes, the pathogen itself is smaller than this, but the droplet that carries it is larger, and is easily captured by the filter according to Linsey Marr, an environmental engineer and professor at Virginia Tech.
Many HVAC systems also have an activated carbon filter. These are designed to absorb smell, but there is no evidence that they help with covid-19.
An electronic ionizer helps clean air in a different way. An ionizer is a type of filter installed in your ductwork, that uses a two part system to clean particles. In the first step, a simple filter is used to catch the largest particles, and then anything that passes through is sent to through an ionizer that emits electrically charged particles.
This causes them to stick to oppositely charged pollutants in the air, and makes them so heavy they fall. This can either go onto a collection plate that will need cleaned, or stick to objects around your home instead.
One final method of filtering air is UV light. UV light is well known for its germicidal properties, and the website for the FDA says, “UVC radiation has been shown to destroy the outer protein coating of the SARS-Coronavirus. The destruction ultimately leads to inactivation and destruction of the virus.”
One thing many experts agreed on is that air filters should not be your first line of defense against the coronavirus. This is because you are more likely to be infected through direct interactions with an infected person rather than the air circulating around the house.
If you are sitting next to an infected person having a chat with them, infection is more likely to occur from that contact rather than the A/C duct on the other side of the room.
Still, filtration can be a powerful tool in reducing infections, and should be considered as an additional measure after basic safety such as social distancing and proper hand washing have been taken into account.