Overnight temperatures plummeted below -5°C Air Pollution on Sunday, with a repeat expected on Monday night, bringing widespread frost and ice to Northern Ireland. The cold and calm conditions, however, pose a challenge as they prevent the dispersion of emissions from home heating and transport.
Air Pollution
Consequently, the Department of Agriculture, Environment, and Rural Affairs (Daera) and the Department of Health have issued a ‘High Air Pollution Alert’. Users of the Air Aware app received a text alert warning of the potential for isolated areas of high air pollution.
The frigid conditions prompted health advisories for those with respiratory and cardiac conditions to remain vigilant about symptoms and seek medical advice if any changes are noticed. Approximately two-thirds of Northern Ireland relies on oil for home heating, releasing particles that can be inhaled. The current cold weather conditions exacerbate this concern.
In the UK, air pollution information services typically use the Air Quality Index and a banding system approved by the Committee on Medical Effects of Air Pollution. This system utilizes an index from one to 10 to communicate air pollution levels in a manner similar to the pollen index. It considers five pollutants, including nitrogen dioxide, sulphur dioxide, and other particles.
On Monday, Strathfoyle near Londonderry recorded high pollution levels, reaching seven on a scale from 1 to 10. Moderate levels of five were observed in Belfast city centre, Rosemount in Derry, and Newtownstewart. The cold weather conditions also led to icy roads, prompting a yellow weather warning for ice in large parts of counties Armagh and Down.
The lingering fog observed across some areas of Northern Ireland on Sunday is explained by a temperature inversion phenomenon. Under the dominant high-pressure area, cold air gets trapped underneath, preventing its escape and leading to the formation of fog. This temperature inversion also traps pollutants near the ground, diminishing air quality. The weak January sunshine hinders the burning off of fog from above, making a change in wind direction or the introduction of drier air necessary for dispersion.
