High levels of air pollution have been detected in Northern Ireland, the Department of the Environment said.
The Newry area has recorded the highest pollution, with moderate levels noted in Armagh, Ballymena, Belfast, Lisburn, North Down and Londonderry.
The problem has been linked with the build-up of emissions from vehicles and home heating during the current calm, cold weather conditions in the region.
With weather set to remain similar through the rest of this week, officials said there was a possibility that high or very high levels of pollution could be recorded in urban centres across Northern Ireland.
The department said during periods of high air pollution the symptoms of people with lung or heart disease could worsen but healthy people were unlikely to experience any ill effects.