High levels of air pollution (particulate matter) are currently being monitored in Derry.
Other areas affected are Armagh, Belfast, and Newry.
Moderate levels are being monitored in some other urban centres across Northern Ireland. Air quality is likely to improve from this evening and into tomorrow as winds strengthen.
The high levels of pollution are believed to be as a result of local pollution sources such as road vehicles and home heating emissions combined with cold, calm weather conditions in which pollutants are not being dispersed.
During periods of High Pollution the symptoms of people with lung or heart disease may worsen. Healthy people are unlikely to experience any ill effects.
Hourly updates on levels of particulate matter (PM10), sulphur dioxide, nitrogen dioxide, ozone and carbon monoxide are available on the Department’s website: http://www.airqualityni.co.uk and the Department’s freephone helpline (0800 556677), which also offers health advice to those who may be particularly sensitive to air pollution. Subscribers to the Air Aware service will also receive notification of this alert: see http://www.nidirect.gov.uk/air-pollution-and-health