Levels of traffic related air pollution in parts city is outside safe levels.
The Environmental Protection Agency has released a new report.
It found areas with high-traffic volumes are at risk of breaching EU limits for nitrogen dioxide.
The air pollutant strongly associated with urban areas as its main source is from exhaust fumes from cars buses and trucks.
The city centre and areas around the M50 are worst affected.
Environment Minister Richard Bruton has committed to taking "immediate action" to improve air quality in the capital.
Children and the elderly are particularly vulnerable to the effects of nitrogen dioxide.