It was promoted as a spectacular carnival: five P&O ships in Sydney Harbour at the same time. It may have been for the cruise company, but it was a spectacular disaster for us.

The other side of the story is more compelling, and certainly more breathtaking in a different way: cruise ships are the most polluting of the main vessel types that come into Sydney Harbour. Passenger ships have the highest average emissions per vessel for three of the four major pollutants, causing more breathing difficulties.

P&O owner Carnival Cruises have been keen to showcase just how many dozens of eggs, litres of milk, and kilograms of fruit and vegetables will be consumed aboard those five ships in Sydney Harbour over the next year.

But instead of these facts, Sydneysiders might want to be informed of just how many tons of particulate matter (PM 2.5 and PM 10), sulphur dioxide, nitrogen gases, benzine, toluene, and formaldehyde these ships emit. These cause excessive morbidity and mortality at all ages, especially due to eye and mucous membrane disorders, lung and cardiovascular diseases, and cancers.