An article has recently appeared in the British Medical Journal warning of the dangers to public health in the UK caused by air pollutants.
In 2011 a report from the House of Commons Environmental Audit Committee suggested that the costs to society from poor air quality were on a par with those from smoking and obesity. Air pollution has fallen sharply over the last 25 years, in particular nitrogen oxide levels have dropped by two thirds and particulates have halved. However, whilst the pollution levels have fallen, the medical profession is now better able to quantify the damage caused.
Studies in the United States were able to calculate the increased risk to the population at various levels of concentration of pollutants. Translated for the UK population this was seen as having an effect on mortality equivalent to 29,000 deaths at typical ages of death in the UK.
The UK has met all European targets on particulates but has not been able to sufficiently reduce levels of nitrogen dioxide and the European Commission has launched an action against the UK. Meanwhile, the UK Supreme Court has ruled that the UK should draw up a plan by 31 December to cut nitrogen dioxide levels.
The main reason for UK non-compliance is diesel. Diesel engines emit more particulates and nitrogen oxides (NOx) than petrol engines, despite a succession of EU standards designed to clean them up. Particulates are reduced by filters that are fitted to newer vehicles approved under the Euro 5 regulations, but official tests used to measure NOx seriously underestimated the amount the newer vehicles would produce.
Real world NOx emissions from Euro 5 compliant cars approved since 2009 now exceed those on cars approved under Euro 1 regulations in 1992 and “are in the region of five times the limit value” the European Commission has admitted. “This has a major impact on concentrations of NO2, ozone, and secondary particles across Europe.”
The UK has encouraged the use of diesel cars through a favourable tax regime based on carbon dioxide emissions, with the result that in 2011 diesels outsold petrol cars in the UK for the first time. The rapid growth of diesel cars with high NOx emissions was thus the result both of mistaken environmental incentives and the failure of the EU testing regime.
The article in the BMJ suggests that the long term answer is cleaner vehicles, such as electric, hybrid, or hydrogen powered. The Euro 6 regulations that came into force last September are tougher but tests to ensure vehicles meet them won’t be introduced until 2017.
The introduction of low emission zones is seen as having worthwhile short term effects such as in London since 2008 where heavy vehicles that do not meet emission standards either have to clean up or pay £100 or £200 a day, depending on size, to enter the zone. Cars are not currently included but will be when the ultra-low emission zone is introduced in 2020. However, the new zone will cover a much smaller area (the congestion charge area), risking displacing polluting vehicles on to neighbouring streets.
Transport for London claims that when all parts of the plan are implemented, NOx emissions in the zone should fall by up to 51 per cent. Other cities have been reluctant to follow, and there is no national framework. Germany has 50-60 low emission zones, the UK only one, plus three more limited efforts in Oxford, Norwich, and Brighton.