Brazil's Ricardo Campello falls after going airborne during the wave sailing competition at the Gran Canaria PWA Grand Slam at Pozo Izquierdo beach in the Canary Islands July 17.
The level of emissions they cause will depend on how the electricity to run them is generated, while brakes, tyres and roads all create tiny airborne particles as they wear out.
We've seen the police sort of taking away anything that could become airborne, anything that isn't really connected to the ground at this point, because there are concerns.
Our airborne programme and our satellite programme have been deployed to understand how our rainforests are changing, how temperate forests are changing, African savannahs and even tropical coral reefs.
Its guidance temporarily said there was evidence that when an infected person coughs, sneezes, talks, sings or breathes, infectious droplets and airborne particles could stay in the air and travel distances beyond six feet.