How Can Air Purifiers Remove Viruses?

2023-10-26 10:10:54

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“ This article compares ozone, ultraviolet light, electrostatic collection, and high-efficiency filter media as technologies used to address airborne viruses. ”

At a time when respiratory safety is receiving particular attention, interest in air purifiers has increased, especially in products designed to address viruses. An earlier statement by Zhong Nanshan's team also indicated that air purifiers can help reduce the risk of virus transmission. Which air-purifier technologies are genuinely effective?

Viruses are difficult to remove because they are extremely small. The article describes them as about 0.1 µm in size, or one-thousandth the size of bacteria. Viruses are also non-cellular life forms, so many methods that remove bacteria may not work on viruses.

Air purifiers marketed for virus removal mainly use ozone disinfection, ultraviolet disinfection, electrostatic collection, or high-efficiency filter media. These technologies work in different ways and therefore differ in effectiveness.

Ozone

Virus-removal capability: ★★★★★

Safety rating: ★★

How it works:

Ozone can inactivate viruses rapidly by oxidizing different parts of the virus. It can directly damage the protein shell and then damage the virus's DNA or RNA. Ozone may also interfere with a virus's ability to attach to a host.

Higher ozone concentrations can produce a more thorough effect, but excessive ozone can harm the respiratory, nervous, and immune systems as well as the skin. Long-term exposure to excessive ozone may also carry a potential cancer risk.

Ultraviolet light

Virus-removal capability: ★★

Safety rating: ★★★

How it works:

A common UV lamp is installed inside the purifier. Ultraviolet light with a wavelength of 200–290 nm can penetrate the viral shell and damage the DNA or RNA inside, preventing replication and thereby inactivating the virus.

In practice, exposure time and the distance from the light source greatly affect the result. For many air purifiers with a UV-disinfection function, the advertised virus-removal rate may actually be due to the high-efficiency filter installed inside.

Electrostatic collection

Virus-removal capability: ★★

Safety rating: ★★★

How it works:

Electrostatic collection can attract passing virus-carrying particles to a collector and uses high voltage in an attempt to inactivate them. However, the article notes that reliable evidence for this mechanism is currently lacking. The reported removal rate of purifiers using this technology may instead come from their filters.

High-efficiency filter media

Virus-removal capability: ★★★★☆

Safety rating: ★★★★★

How it works:

High-efficiency filter media can capture PM2.5, pollen, and bacteria and can also remove virus-carrying particles. The article states that this effect has been verified by several testing organizations. Filtration does not generate ozone, ultraviolet radiation, or similar harmful by-products.

Filter media are divided into strict grades according to performance, although the grading systems and criteria vary by country.

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How Can Air Purifiers Remove Viruses?

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