Tens of thousands of people are dying from breathing in vehicle emissions, according to a report sponsored by the World Health Organisation, finds Hugh Oram
Despite the advent of low emission engines and more rigorous regulations, vehicles are still spewing out pollution and a recent research paper suggests exhaust emissions are killing tens of thousands of people.
Reducing pollution from road vehicles, through better emission technology and the implementation of European directives, is having a beneficial effect, but it all takes time. This while the national car pool continues to expand and traffic jams get worse.
The ban on bituminous coal sales has been an enormous help in reducing urban air pollution, but increasing volumes of cars and greater traffic congestion have offset the good work.
It is estimated that about 14 per cent of the State's greenhouse gas emissions come from transport, with road transport responsible for three-quarters of that.
Since leaded petrol was phased out, other emissions from road traffic have become a greater threat to air quality in Ireland, especially in urban areas.
The pollutants causing concern include nitrogen dioxide, PM10 emissions (fine particulate matter) and benzene. A recent research report, sponsored by the World Health Organisation (WHO), suggested that traffic pollution is killing tens of thousands of people across Europe each year. Researchers studied deaths in Austria, France and Switzerland and found that 6 per cent - more than 40,000 a year - were caused by air pollution. Of these, 20,000 were blamed on the microscopic particulates found in vehicle exhausts.
The study, led by Dr Nino Kunzli from the University of Basle in Switzerland, also found that in these countries, traffic fumes accounted for 25,000 new cases of chronic bronchitis in adults, 290,000 cases of bronchitis in children and more than half a million asthma attacks.
The WHO commissioned the report because of its concerns about the human and economic costs of traffic pollution.
Dr Brian Broderick and his colleague, Bruce Misstear, of Trinity College, Dublin, have been researching traffic-related air pollution for the past five years or so.
They have developed a state- of-the-art air quality monitoring unit and also work with computer-based models to work out the roadside pollutant concentrations caused by traffic.
"In urban areas, such as Dublin and Cork city centres, motor vehicles are the most important source of some air pollutants, notably carbon monoxide and oxides of nitrogen.
"PM10 emissions are important, while there are other pollutants, such as sulphur dioxide, that aren't emitted in large quantities by motor vehicles," explains Dr Broderick. PM10 is emitted in large quantities from diesel rather than petrol engines, he explains.
Dr Pat Manning, a respiratory consultant on the medical committee of the Asthma Society of Ireland, says that all ages can suffer from the effects of air pollution from exhaust emissions.
"Carbon monoxide and nitrogen dioxide can be quite harmful, worsening asthma," he says. In addition, PM10 emissions from diesel fuel can lead to chronic lung disease. In heavy or static traffic, the effects of pollution are maximised.
The problem is particularly acute in Dublin, where around 300,000 people are on the move by car every day, and in other urban areas. Traffic levels in Dublin have already reached the levels that were originally predicted for 2010.
The use of catalytic converters in cars since 1993 has helped the situation, for as Conor Faughnan of the AA says, a new car puts out about 3 per cent of the exhaust emissions of one made 10 years ago. He also warns against stereotyping the car as the great environmental ogre. Other sources, such as the electricity industry and agriculture, contribute much more to air pollution.
The increasing popularity of diesel cars has not helped matters, with about 14 per cent of private cars now powered by diesel - a fuel that emits all those tiny, but harmful, particulates.
Conor Faughnan suggests the big problem continues to be particulate emissions from diesel fuel. Another adverse factor is the tendency towards larger vehicles, such as MPVs, which use more fuel and produce more emissions.
The speed of traffic also impacts on emission levels, and Dr Broderick of Trinity College explains why slow traffic makes pollution much worse. "Carbon monoxide emissions are much higher, for example, when the vehicle travels at a slow average speed, say, 15 mph, than when it travels at a higher speed, say, 50 mph.
"Also, the short rapid accelerations that come with queuing movements at junctions produce elevated emissions of some pollutants."
It's not an entirely urban problem. In rural areas, pollution from motor vehicles can have an adverse effect on crop production. At a global level, carbon dioxide emissions from vehicles contribute to climate change effects.
Thankfully, air pollution from traffic is being measured more effectively now. Dublin City Council, for instance, has a network of monitoring sites across the city. Results from this network show that the monitoring site in College Street in Dublin city centre has the worst level of PM10 emissions in the city. Wood Quay PM10 levels are also high.
Similar monitoring networks are run by other local authorities across the country and results from these, as well as from other bodies, and from the monitoring work done by the Environmental Protection Agency (EPA) itself build up into the EPA's annual assessment of air quality. The EPA currently has interactive air quality maps under construction.
It is running a large research project on how traffic impacts on air quality in partnership with a number of universities and councils both here and in Britain, but Dr Broderick says that it's too early to report any findings.
With the steady build up in traffic levels and congestion, there are no easy solutions to this contribution to air pollution. However, Dr Broderick suggests that one approach would be to divert traffic flows away from areas with high concentrations of pollution.
"Alternatively, specific streets could be prioritised to ensure free flowing conditions in which emissions are lowest."
Under European legislation, progressive reductions have been made in the emission limits to be met by new cars, subsequently checked by the National Car Test.
Another longer term solution could be along the lines of VW's new prototype car, the One Litre, which is described as the world's most economical vehicle powered by fossil fuels - it does 250 miles to the gallon, but it's a long way from going into production.
Ongoing research into other types of vehicle propellant, including battery power and hydrogen, could help the process of producing cleaner fuels.
But the solutions are piecemeal and long term and there's no quick fix for anyone sitting in a traffic jam in Dublin city centre, being choked by fumes from other vehicles. A growing number of cyclists now wear masks travelling round the city - motorists have yet to follow suit.