Title here "Covid loses 90% of ability to infect within five minutes in air" is a little misleading. From the abstract:

"A decrease in infectivity to ~10 % of the starting value was observable for SARS-CoV-2 over 20 minutes, with a large proportion of the loss occurring within the first 5 minutes after aerosolisation."

Interesting takeaway from the paper:

The paragraph titled: "Airborne longevity appears similar for different SARS-CoV-2 variants" and Figure 4.

So they take strain into account, and it doesn't seem to effect things.

Note I'm not a molecular biologist or a virologist, so I can't really confirm or reject their methods.

The title was taken from the Guardian article which linked to the paper [1]. I thought the paper more interesting and the Guardian title, although a little sensationalist, was a better jump point than The Dynamics of SARS-CoV-2 Infectivity with Changes in Aerosol Microenvironment.

1. https://www.theguardian.com/world/2022/jan/11/covid-loses-90...

For a counterpoint:

"How coronavirus survives for hours in aerosols" https://aip.scitation.org/doi/full/10.1063/5.0059908

The title here is imprecise and misleading. "Droplets that contain the Covid virus" would presumably be a bit more precise. Also the paper is a preprint, so one should be particularly careful with strong statements.