Yeah, as you say, the main source of air pollution in Dublin is cars. Those are basically outside of the EPA's remit. It has been very effective in cleaning up _industry_, which is in its remit, though a lot of this was playing catchup with the rest of Western Europe.

The cars are basically some combination of the NTA's and the local authorities' fault; a massive expansion of Dublin's bus and commuter rail capacity, and a new metro system, are all years behind schedule, largely due to planning permission nonsense (though also due to disastrously incorrect government planning about 15 years ago, which assumed that Ireland would go back to its traditional perma-recession after the financial crisis, with the result that starting these expansions was delayed by about a decade).