Road traffic is now the greatest threat to urban air quality in Ireland, making it "essential to break the link between car-ownership and car-use", according to the Environmental Protection Agency (EPA).
It notes that the number of vehicles on the road here rose by 60 per cent between 1990 and 2000 as a direct result of dramatic economic growth, with private cars accounting for the major part of this substantial increase.
Increased numbers of vehicles and use of cars had caused significant traffic congestion, air and noise pollution in urban areas, with EU limits on PM10s (very small particles) breached repeatedly in Dublin's College Street during 2000.
Advances made by improved emission controls in limiting airborne pollutants "have been partially offset by the continued growth in the number of vehicles", the EPA says, adding that this was likely to intensify as car numbers rise.
As a result, journey times in the Dublin area had more than doubled on certain routes (Lucan and Navan roads) from 1991 to 1999. "Overall, continued growth in road transport in all urban areas including Dublin is unsustainable," the agency says.
With surveys showing that more than 62 per cent of all commuters travel to work by car, it suggests that "an integrated, efficient public transport system is urgently required" as well as routes to divert heavy goods vehicles away from urban centres.
"Only one in five people uses more environmentally sustainable forms of transport to travel to work", the EPA notes. "A total of 13.3 per cent of persons in employment walk or cycle and approximately 8.5 per cent travel by bus, train or DART."
It says public transport in Ireland "has been seriously neglected and poorly funded in the past". Although some progress has been made in providing cycle lanes and quality bus corridors, there is still "major scope for improvement".
On a more positive note, the EPA notes that smoke levels in many urban centres have decreased dramatically due to the banning of smoky coal - showing how "a well-targeted policy can bring about significant environmental improvement".
However, while emissions of sulphur dioxide fell by 29 per cent between 1990 and 2000, emissions of nitrogen oxides increased by 6 per cent over the same period. In both cases, substantial reductions will be needed to meet international obligations by 2010.
Referring to climate change, the EPA notes that Ireland's greenhouse gas emissions in 2000 were already 24 per cent higher than in 1990 and warns it will now be necessary to achieve substantial reductions to cap the increase at 13 per cent by 2010.