A RECENT government report has revealed that toxic nitrogen dioxide emissions around major ports and sea routes in the UK are four times higher than previously suggested.
Levels of sulphur dioxide, another harmful pollutant, are three times higher, the UK's Independent reported.
According to experts, shipping pollutants which are concentrated around major port cities such as Southampton, Grimsby and Liverpool, are a significant cause of concern for the health of local populations.
Long-term exposure to pollutants like nitrogen and sulphur oxides (NOx and SOx) can contribute to a range of health problems, from asthma to cancer, and has been linked with the deaths of around 40,000 people in the UK annually.
The Government is currently facing heavy scrutiny and potential legal action from the European Union after failing to curb its air pollution levels.
However, the conversation surrounding toxic pollutants has focused largely on road vehicles, and little effort has been made to address the pollution coming from ships that pass through UK waters.
'Cars are not the only sources of emissions in our air. Ships are more fuel efficient than road vehicles, but they use fuels which produce greater levels of emissions than road diesel,' said Dr Matt Loxham, an air pollution toxicologist at the University of Southampton.
'This, in combination with the concentration of vessels in relatively small port areas and shipping lanes, is the reason why there is concern around shipping emissions.'
New analysis presented in a National Atmospheric Emissions Inventory (NAEI) report to the Government concluded shipping is a far greater source of pollution in Britain than estimates made in 2014 suggested, with about 10 per cent of the country's NOx emissions coming from ships.
The increase in estimated air pollution has arisen from a more thorough analysis that found the amount of fuel being consumed by domestic ships is 2.5 times that of previous figures.
Shipping is a major contributor to both air pollution and greenhouse gas emissions, but one that is often overlooked by policymakers.
Global estimates suggest ships are responsible for 15 per cent of NOx and 8 per cent of sulphur gas worldwide. International shipping also produces around 3 per cent of human greenhouse gas emissions - roughly double that of aviation.
'The reason for this is that ships burn the dirtiest fuel - they essentially run on the lowest grade waste product that you get from a refinery, called heavy fuel oil,' said Dr Tristan Smith, a shipping researcher at University College London who contributed to the report.
Despite this, Dr Smith said regulations on shipping pollution are insufficient, and its greenhouse gas emissions are not even accounted for in the Paris climate agreement.
Not only does ship fuel itself contain high levels of sulphur that is emitted as SOx, ship engines are not controlled to anywhere near the same extent as road vehicles, resulting in high levels of NOx.
'The only good news here is that a lot of these emissions are happening out at sea, meaning less human impact,' said Dr Smith.
'But still, anyone who is living in a port city is getting badly impacted at the moment because there is such light regulation on the exhaust.'