Scientists studying Covid-19 agree that catching the virus outside is much more difficult than indoors.

The virus is typically spread when tiny particles from an infected person are transmitted to another, but that becomes harder in outdoor settings.

Experts say an easy way to understands how the aerosols and droplets carrying the virus behave is to compare it to cigarette smoke.

Inside, the smoke lingers and hangs in the air, but outside, it can quickly disperse.

"What Covid likes is dark, cold environments, indoors where there is no UV light," said Nicola Fletcher, assistant professor at UCD's School of Veterinary Medicine.

"Outdoors there's greater air movement, so you have greater turnover of air, so less virus is able to linger over periods of time," she added.

Assistant Professor of Virology at Trinity College Dublin Kim Roberts agrees and said
the transmission of Covid-19 is more difficult outdoors because of various factors.

"There's a lot more fresh air, there's movement of air, so you get much greater dispersal of any respiratory droplets that you're generating as you're breathing, talking, shouting.

"Also when those droplets leave you they tend to shrink, they dry up and that helps to deactivate the virus," Dr Roberts said.

The UV light from the sun also helps.

"So all of these things are helping to destroy the virus and stop it from being infectious before it's got a chance to infect someone else."

Dr Roberts said that indoors, if there is poor ventilation, the virus can accumulate in that space, and there is a greater chance of it travelling over two metres.

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