Levels of harmful air pollution excluding greenhouse gases have continued to fall, according to new figures from the National Atmospheric Emissions Inventory (NAEI) published by Defra today.

The largest air pollutant emissions cuts were in lead and 1, 3-butadiene, which fell just over nine per cent and seven per cent respectively. Emissions of harmful nitrogen oxide and carbon monoxide also fell by between 0.5 and five per cent.

The results will be interpreted as an endorsement of the Environment Agency's Air Quality Strategy, which aims to minimise air pollution from industrial sources. The new figures showed that emissions of nearly all gases covered in the Air Quality Strategy (AQS) fell between 2005 and 2006.

However, the report also raised some areas of concern. Particulates (PM10) emissions rose just over one per cent and the results, while sulphur dioxide emissions of 0.68m tonnes may have fallen two per cent in 2006 but are still some way short of EU targets designed to acid rain and the formation of ground-level ozone which demand emissions fall to 0.59m tonnes by 2010.

In related news, The US Environmental Protection Agency (EPA) announced a tightening of US smog standards yesterday.

Current air quality standards require average concentrations of ozone at ground level over an eight-hour period to be no higher than 84 parts per billion, but under the proposed changes this would be tightened to 75 parts per billion.

The decision however was condemned by environmental groups after it rejected the ruling of the EPA's own scientific advisory council that the standard should be tightened to between 60 and 70 parts per billion.