Two Northern Ireland cities are among dozens of places in the UK which suffer from worrying levels of air pollution, a report has said.
Londonderry was among 31 towns and cities identified by the World Health Organisation as exceeding safe levels of fine particle pollutants known as PM2.5 in 2015.
Another 15, including Armagh, are at the limit.
The particles, which come from sources such as transport, industry, coal plants and burning wood, fuels or waste, are linked to conditions including stroke, heart disease, lung cancer and respiratory infections.
The report said seven million people a year worldwide are dying due to poor air quality, and nine out of 10 people are exposed to levels of air pollution which are dangerous to their health.
Clean air campaigners called for the UK Government, which has faced legal action over its failure to meet legal targets on another air pollutant, nitrogen dioxide, to take steps to stop people breathing dirty air.
James Thornton, chief executive at environmental law charity ClientEarth, said: "These new statistics show a worrying level of this dangerous air pollution across the country."
He added ministers should commit to a new Clean Air Act, adding: "Without it, many people across the UK will continue to pay with their health."
Levels of PM2.5 particles in the air in Port Talbot, Wales, were recorded as 18 micrograms per cubic metre in 2015, nearly double the WHO recommended limit of 10.
Other cities including London, Nottingham and York were also above safe levels in 2015.
The report shows that some towns and cities, including Manchester, Scunthorpe, Liverpool and Salford, did not have figures for 2015 but had breached the recommended limits in the most recent year data was available.
Alison Cook, director of policy at the British Lung Foundation, said: "How much more evidence do we need to see before the Government sets new legal limits on pollution levels to protect the nation's lung health?"
A UK Environment Department spokesman said: "While air quality in the UK has improved significantly since 2010, this report from the WHO clearly shows the impact air pollution is having.
"Tackling this important issue is a priority for this government which is why we have a £3.5bn plan to improve air quality and reduce harmful emissions and will set out further actions through a comprehensive Clean Air Strategy later this year."