Rural areas see more days of heavy pollution than urban neighbours
According to Government figures released this week air in the UK is gradually getting cleaner but the countryside is suffering more days of heavy pollution than the cities.
They show little change in urban areas, with an average of 22 days of moderate or higher air pollution compared with 23 in 2004.
But rural areas saw a modest yet significant improvement, with an average of 41 days compared with 44 in the previous year.
When given a cursory glance the figures would seem to make a suggestion that flies in the face of our concept of smog-choked cities contrasted with fresh, country air.
But a Defra spokesman told edie that the number of polluted days did not tell the full story.
"Rural pollution is mainly caused by ozone while in the cities there are particles and sulphur dioxide that also contribute to the bad days," he said.
"While the peak levels of ozone are decreasing there is a long-term increase in average background levels.
"The combination of these two factors shows up on the indicator as no overall trend."
He said the weather also had a huge impact on ozone levels so a particularly warm summer or cold winter could skew the figures.
Much of the ozone reaching the UK is blown in from Europe, making its control and reduction a regional matter.
"That is why we continue to be committed to Europe-wide action to tackle ozone," he told edie.
As to why the invisible clouds of ozone were affecting our farms and fields but not built up areas, he said this was due to the complex chemical process that governed the formation and destruction of ozone in the atmosphere.
"Nitrogen oxides emitted from fossil fuel combustion both create and destroy ozone," he said.
"Locally high emissions of nitrogen oxides, such as from traffic in urban areas, tend to favour ozone destruction, resulting on formation of nitrogen dioxide. "This results in ozone levels generally being lower in urban areas and nitrogen dioxide levels being higher.
"Ozone levels tend to be higher in rural areas where there are less local emissions of nitrogen dioxides to destroy any ozone that has formed in the atmosphere."
The air quality data is one of 68 indicators used by the Government to see how Britain is performing against its Sustainable Development Strategy.
It presents trends for annual levels of particulate and ozone pollution, the two pollutants thought to have the greatest health impacts, as well as the number of days on which levels of any one of five pollutants were moderate or higher.
Local Environment Minister Ben Bradshaw welcomed the figures, but stressed that more work is needed. He said: "Air pollution affects people's health and their quality of life. In general we continue to make progress but more needs to be done to tackle pollutant concentrations, particularly nitrogen dioxide, particles and ozone.
"International, national and local action to tackle air pollution is working, and we are reviewing our Air Quality Strategy to find potential extra measures to generate health benefits and move us closer to meeting our objectives.
"Local authorities have an important role to play in helping the government cut pollution and make our air cleaner, and many of them are implementing measures or developing action plans.
"However, a number of authorities in England have fallen behind the rest. Local people have a right to expect their councils to do whatever they can to ensure cleaner air."
By Sam Bond