FEARS of air pollution have surfaced in Dublin after excessive levels of a potentially dangerous chemical were recorded.
The amount of nitrogen dioxide in the air at a site beside the M50 was found to have breached permissible quantities.
Results made available by Dublin City Council show the "exceedance" occurred at a sampling site adjacent to the motorway in the highly populated west Dublin suburb of Blanchardstown.
Sarah Middleton of the local authority's air quality unit said nitrogen dioxide is "normally experienced" as a result of emissions from car exhausts.
While she did not specifically name the M50, she said the site is by an eight-lane road in Blanchardstown.
Ms Middleton said this is "obviously a good indication that it is from traffic".
Exposure to the pollutant has been associated with respiratory illness in young children, while long-term inhalation may lead to an increased risk of respiratory infection.
Ms Middleton said Dublin has a higher pollution level of nitrogen dioxide than most other cities in Ireland because of its "greater population and higher traffic volumes".
However, other pollutants such as sulphur dioxide are not so prevalent.
Overall levels of pollution in the capital are actually decreasing. One of former minister Mary Harney's achievements was the introduction of a smokeless coal ban.
The prohibition has led to a massive reduction in sulphur dioxide to the point where analysers sometimes have difficulty picking up levels in the atmosphere.
In addition, the council's heavy goods vehicle ban in the city has resulted in decreases of nitrogen dioxide in the zone.
Ms Middleton gave an overview of the interim air quality results for the Dublin region in 2010 at the local authority's environmental committee meeting.
In 2009, Dublin City Council recorded high levels of nitrogen dioxide at another of its sites.
All the four Dublin local authorities were required to develop an action plan to deal with the problem. Ms Middleton said the plan is nearing completion and has to be submitted to the Environmental Protection Agency by the end of 2011.