It's one of the most profitable leisure industries in the world, but campaigners say the cruise industry could be contributing more than it needs to the problem of air pollution.

Cruise ships have huge power demands, and to power on-board facilities such as lights and water treatment plants, they run their engines 24/7 whilst moored up in ports like Southampton in Hampshire.

Dr Christelle, a GP in the Woolston area of the city, says air pollution is causing health issues and PhD student Natasha Easton, who is looking at the effect tiny particles of soot and smoke from cruise ships, says the finest particles can get "very deep in the body... and potentially have the worst health effects."

The Cruise Liner Industry Association that represents several companies says the cruise industry brings about 10 billion euros in to the UK economy a year, and takes the lead on developing greener and more sustainable technology for the whole shipping industry.

A film by Ben Moore