Air pollution levels in Belfast have been branded among the worst in the UK, with one monitoring station breaching EU legal limits for three years in a row.
The station at Stockman's Lane recorded an annual average nitrogen dioxide reading of 50 microgrammes per metre squared for the first three months of 2017 - 25% higher than the EU legal limit of 40 microgrammes per metre squared.
The same average score was also recorded in 2015 and 2016, according to The Times journalist Peter Yeung, who carried out an investigation into the impact of air pollution in the UK which found a rise in the number of communities blighted by toxic air. The Belfast air pollution figure, derived from DEFRA stats, was one of the worst in the UK, he said.
"There has been no decline - despite supposed political attempts to reduce emissions," he said.
Diesel cars are among the leading producers of nitrogen dioxide, prompting calls for a crackdown by Doctors Against Diesel founding member Jonathan Grigg, who said the cars should be removed from the roads as soon as possible.
"Exposure over a very long time has an insidious effect. It suppresses the lung growth of children, it's involved in the onset of asthma, a decline in lung function as you age, and there's emerging evidence of it causing cognitive problems and also reduced growth of foetuses," he said. "Targeting diesel cars is a very easy way to reduce emissions. At the moment, it's still relatively advantageous to drive a di esel vehicle - there's not enough disincentive."
Belfast Green Party councillor Georgina Milne, who is a research scientist, said she was worried, but not surprised at the news. "Indeed, there are four air quality management areas in Belfast declared for breaches of Nitrogen Dioxide (NO2) and Particulate Matter (PM)," she said.
"One of these areas is on the busy Newtownards Road, in my East Belfast constituency. Indeed, many residents have spoken about the poor air quality."
Cllr Milne said transport emissions are a huge issue right across Belfast and it is time to move towards more sustainable transport solutions.
"The human and financial cost of doing nothing is huge - over 500 deaths in Northern Ireland per year are attributed to air pollution. This represents more deaths per year than road traffic collisions and passive smoking combined," she said.
"Deaths from air pollution-related disease cost the NHS over £20bnper year - that's nearly 1/5th of the overall budget.
"We need the traditional parties to come together, to form an Executive and deliver a budget so that these life and death issues can be tackled."
Friends of the Earth activist, Declan Allison said: "Air pollution is linked to lung cancer, heart disease, asthma and diabetes, with 40,000 people in the UK dying early each year as a result. It is unacceptable to persistently be in breach of legal air quality limits."
In a statement a spokeswoman for the Department of Agriculture, Environment and Rural Affairs said it works with Defra to "monitor air pollutants to assess compliance with the Air Quality Directive".
She said: "With regard to air quality in Greater Belfast, the Department has been working with the Department for Infrastructure and Belfast City Council to draw up an Air Quality Action Plan, which will be part of a UK-wide consultation in due course.”