How Long can the Coronavirus Survive on HEPA Filters?

Studies have found air purifiers with HEPA filters are highly effective at filtering out COVID-19 coronavirus and even smaller viruses.

But viruses can remain on surfaces for scarily long periods of time. It’s led to incredible-sounding headlines about how long viruses last.

Covid virus lifespan lasts long time on cuirse ship

The thought of a virus stuck in an air purifier’s HEPA filter sounds scary. But a “detectable” virus is very different from a “viable” virus. A viable virus is one that’s alive and still able to infect someone. “Detectable” viruses are just that – detectable, but not necessarily viable.

How Long Can Viruses Last on HEPA Filters?

To answer this question, it’s important we look at how long viruses remain viable on HEPA filters. It’s likely that inactive (“dead”) viruses will remain stuck in HEPA filters for a very long time. But what’s more important is how long are they active and able to re-infect.

Researchers at the University of Hong Kong tested how long viruses remain viable on 6 different surfaces. They sprayed the H1N1 flu virus on common household materials including plastic, wood, and steel, and tested viability up to 24 hours.

H1N1 Flu Virus

Unfortunately, they didn’t test any HEPA filter material. But they tested something fairly similar: J-cloth material. It turns out this J-cloth material is actually surprisingly similar to the electrostatic material used in HEPA filters.

J-cloth material fabric tested virus lifespan

For the HEPA-like J-Cloth material, the tests found that the virus was completely non-viable in less than 5 hours.

Influenza A virus viability on different surfaces

The H1N1 virus remained viable the longest on hard, non-porous surfaces like stainless steel and plastic. However, the flu was non-viable in under 10 hours for even the worst surface–the stainless steel. The researchers concluded that the H1N1 is “likely to survive up to a few hours.”

Viruses likely last up to a few hours die

Researchers tested the viability of SARS-CoV-2 on masks. This is highly relevant because many HEPA filters are made out of the same plastic fibers as masks. The data showed that 50% of the virus “died” in 80 minutes. It was 99.9% inactive after 13 hours.

Another set of scientists in the UK tested the viability of a range of viruses on HEPA filters, including Bacillus atrophaeus and MS-2 coliphage. They placed the viruses on the HEPA filter and then blew air through the filter at a constant rate to simulate the usage of the HEPA filter.

Survival of viruses on HEPA filter air purifiers

Their data found that the majority of the viruses survived no longer than 2 days. However, the MS-2 coliphage virus – a non-enveloped virus that has been shown to survive longer than an enveloped virus – was able to survive up to 6 days. (The COVID-19 coronavirus is an enveloped virus, not like the MS-2 coliphage virus).

It the Same for HEPAs With The Covid-19 Virus?

The study above is for H1N1 (influenza A), not the coronavirus.  There’s little data available specifically on how long the Covid-19 coronavirus lasts.

The CDC says that the coronavirus may remain viable for hours to even days. A recent study (that has not been formally published yet) tested the viability of the new coronavirus (HCoV-19) and the “old” coronavirus, SARS (SARS-CoV-1). They sprayed the two viruses on plastic, stainless steel, copper, and cardboard.

Coronavirus Viability Time For Cardboard Copper Steel and Plastic Surfaces

They did not test HEPA filters or cloth materials this time. But the closest material to a HEPA filter surface was cardboard. It took 48 hours for the coronavirus to be completely non-viable on cardboard. On stainless steel, a tiny amount of viable coronavirus remained at 72 hours, That’s 7 times longer than the earlier study found for H1N1.

How long does COVID survive on surfaces?

However, it’s important to remember that these tests were done in laboratory conditions, sometimes with very high doses of viruses that aren’t expected to be seen in real-world circumstances. This means these numbers may be exaggerated, as explained in one paper on the exaggerated risk of COVID-19 transmission.

Based on this, it’s unlikely the COVID-19 virus would last more than a few hours on HEPA filter surfaces. However, it’s always good to err on the side of caution. Based on these two studies, a very conservative amount of time it would take to kill the COVID-19 virus on HEPA filters would be 48-72 hours. Therefore, it is important to wear gloves or wash hands immediately after when replacing HEPA filters or cleaning an air purifier.

How long covid-19 virus survices on air purifier HEPA filter

Bottom Line: How Long can the COVID-19 Coronavirus Survive on HEPA Filters

The coronavirus, SARS, and influenza A viruses typically die in under 48 hours, across a range of surfaces. A hardy, non-enveloped virus (MS-2 coliphage) was able to survive up to 6 days on HEPA filters. However, the coronavirus – being an enveloped virus – is unlikely to last this long. A reasonable estimate for the survival of the coronavirus on HEPA filters is 48 hours, with 72 hours being a conservative number.

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5 thoughts on “How Long can the Coronavirus Survive on HEPA Filters?”

    • Hi Pen. Song here.
      Ozone is one of the recommended disinfection regarding viruses. We haven’t done any test on the sufficient concentration or time to kill the viruses or to what extent it will affect the performance of HEPA filters. I believe there are many available paper on such topic. You are welcomed to share here with all the readers for discussion.

  1. Hi, Paddy, In your Bottom Line, you state ” However, the coronavirus – being a non-enveloped virus –” whereas earlier you point out that it is enveloped. Also, I know that there are studies testing detectable Covid-19 in city sewer systems for benchmarks in community exposure. Will there be any similar studies for HVAC filters, especially given the recent CDC statements on airborne virus?

  2. Hi, Paddy.

    Greetings of safety!

    These are very helpful & relevant information. I would like to ask your permission to use your images in you tube VLOG to share information about the HEPA Filter. I am not a seller of any air purifier products.

    Is the following citation enough to give credit to you?

    Smart Air (2020 February 2) Can HEPA Air Purifiers Capture the Coronavirus? Retrieved from

    Thank you so much.


    • Hi Lily,

      We actively promote the sharing and exchange of open data! All of Smart Air’s content is provided under a Creative Commons License, which allows non-commercial sharing as long as attribution/a citation is provided. Your citation placed in the VLOG notes is adequate.

      More information on our sharing policy here:

      Breathe safe!


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