I am aware of recent reports that have indicated that emissions testing was not being carried out in Northern Ireland as part of the annual Ministry of Transport (MOT) test on diesel cars, and of concerns that imports of such cars may result in higher emissions from the Irish passenger fleet. Emissions from road vehicles in general, and from diesel vehicles in particular, are a key source of negative health impacts from a range of air pollutants, including nitrogen oxides (NOx), particulate matter (PM), black carbon and volatile organic compounds (VOCs), especially in urban areas. Any factor which may increase these emissions, or circumvent legally mandated controls on them, is a matter for concern. However I understand that, with a few rare exceptions such as vintage vehicles, any second-hand car imported into Ireland from Northern Ireland will be required to undergo the National Car Test (NCT) if it is more than four years old and the period of validity of its MOT has expired, at which point its emissions will be tested.
For further information on this question, or on matters relating to the NCT, I would refer the Deputy to the Department of Transport, Tourism and Sport.