The Green Party called for "urgent action" to be taken.
The World Health Organisation revealed that 44 out of 51 towns and cities across the UK had failed the test for fine sooty particles smaller than 2.5 microns across that have been linked to heart disease and premature death.
Exposure to the particles, known as PM2.5s, should not exceed 10 micrograms per cubic metre of air, according to the WHO, which carried out the survey.
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Armagh was the worst in Northern Ireland with 14 micrograms per cubic metre. Belfast was next on 12, with Derry next on 11 micrograms per cubic metre.
Green Party NI representative Georgina Milne said she is "not surprised" at the levels of air pollution.
She said: "Indeed, there are four air quality management areas in Belfast declared for breaches of Nitrogen Dioxide (NO2) and Particulate Matter (PM).
"One of these areas is on the busy Newtownards Road, in my East Belfast constituency. Indeed, many residents have spoken about the poor air quality.
"The human and financial cost of doing nothing is huge – more than 500 deaths in Northern Ireland per year are attributed to air pollution. This represents more deaths per year than road traffic collisions and passive smoking combined."
(CD/LM)
