At weekends, parents push babies in strollers and take family photographs in the attractive roof garden that crowns Hong Kong’s Kai Tak Cruise Terminal, seemingly oblivious to the smoke belching from whichever ocean liner happens to be berthed alongside.
“It’s rare to have such a nice big space,” says a young mother from West Kowloon, as she enjoys a stroll with her partner and son.
Behind her, a plume of filthy rust-coloured smoke belches from the exhaust funnel of the 335-metre cruise liner World Dream; smoke full of sulphur dioxide (SO2), nitrogen oxides (NOx) and particulate matter (PM).
Ocean-going vessels (OGVs) are one of the major sources of air pollution in Hong Kong. Although container ships account for 60 per cent of all OGV polluting emissions, cruise liners – which continue to run their engines to power everything from jacuzzis to galley equipment – typically burn up to 10 times more fuel while berthed than do small container ships; and both of Hong Kong’s cruise terminals – Kai Tak and Ocean Terminal – are close to residential zones, business areas or parks.
While idling, a cruise liner such as the World Dream emits as much SO2 as would 25,000 local diesel buses, estimates Martin Cresswell, technical director of the Hong Kong Shipowners Association. That’s almost five times the amount of SO2 emitted by Hong Kong’s entire franchised bus fleet (5,422 vehicles) concentrated on one spot, less than 100 metres from where excited toddlers chase each other among well-manicured flower beds, inhaling deeply as they charge around.
SO2 can cause respiratory problems such as bronchitis and can irritate the nose, throat and lungs. It may cause coughing, wheezing, phlegm and asthma attacks. According to the government’s Centre for Health Protection, not only is there a “strong association” between high pollution and premature deaths due to respiratory and cardiovascular diseases, exposure to diesel-engine exhaust – most shipping runs on diesel – increases the risk of cancer. In June 2012, the International Agency for Research on Cancer, under the World Health Organisation (WHO), reclassified diesel-engine exhaust as Group 1, “carcinogenic to humans”.
On January 1, the “Fuel for Vessels” regulation was implemented in Hong Kong, requiring vessels in Hong Kong waters to use fuel with a sulphur content of no more than 0.5 per cent (beforehand, 3.5 per cent had been the norm). But, as Cresswell points out, that is still 500 times more sulphur than in the fuel used by local buses (0.001 per cent sulphur content).
While there is consensus that the government’s marine and road sulphur caps have reduced SO2 pollution, the regulations have had less effect on other pollutants.
Scientists are particularly concerned about risks from the NOx and PM that are emitted in the exhaust from ships.
NOx gases irritate the mucosa of the eyes, nose, throat and the lower respiratory tract, and long-term exposure can lower a person’s lung function and resistance to respiratory infections, leading to premature death.
They also react with sunlight and other chemicals to form ozone (O3 or smog), which can irritate the eyes and trigger life-threatening asthma attacks, increase susceptibility to fatal respiratory infection, even in healthy people, and aggravate respiratory illnesses.
Particulate matter is identified according to aerodynamic diameter. PM10 and PM2.5 micro particles carry toxic matter and can easily be inhaled, penetrating deep into the lungs. In 2016, a study by the University of Hong Kong School for Public Health found that PM2.5 was associated with mortality from all types of cancer. In Hong Kong, 40 per cent of all PM comes from ships.