Supreme Court air quality ruling may impact on fleet operators

By Categories: NewsPublished On: Friday 3 May 2013

supreme-court-external-view-01The UK’s Supreme Court has ruled that the government has failed to meet its obligations under the European Air Quality Directive to reduce the levels of nitrogen dioxide gas (NO2) in the air.

NO2, of which road traffic is one of the main sources, poses various health risks to humans, including increased likelihood of respiratory problems, and a reduction in immunity to lung infections. It can also cause more frequent or severe attacks in asthma sufferers.

The declaration, which the court said meant “the way is open to immediate enforcement action at national or European level”, was the result of a case brought against the government by environmental law activist group ClientEarth.

The case concerns 17 cities and regions – including the major urban centres of London, Manchester, Birmingham and Glasgow – which are expected to present illegal NO2 levels until as late as 2020, and 2025 for London.

Proceedings are now stayed while a number of technical issues are referred to the European Union’s Court of Justice, but the UK could eventually be forced to take further steps to improve air quality.

The ruling may well have implications for future road transport policy, particularly for operators of vehicles with diesel engines including HGVs, buses and coaches – with the potential for further limits on goods vehicle access to urban areas.

Diesel engines have a higher propensity for the direct emission of primary NO2 than petrol engines. The European Environment Agency has blamed heavy goods vehicles in particular for up to 40-50 per cent of road transport nitrogen oxides (NOx) emission – which includes NO2 – in the countries within its remit.

But the problem is complicated by the fact that technology such as the diesel particulate filters (DPFs) necessitated by London’s Low Emission Zone, designed primarily to reduce particulate matter, can have the side-effect of raising NO2 levels.

A 2007 report by the government’s Air Quality Expert Group claimed that “the fitting of diesel particulate filters to buses substantially increases the fraction of NO2 in vehicle exhaust gases.”

The deadline for complying with limits to NO2 levels passed in January 2010. In that year, 40 of the UK’s 43 ‘zones and agglomerations’ – geographical areas defined for air quality purposes – exceeded the limits.

Image courtesy UK Supreme Court