London faces new smog threat from switch to diesel fuel
Switch to diesel aimed at cutting CO2 has raised nitrogen oxide levels
London has a dirty secret.
Levels of the air pollutant nitrogen dioxide at a city-centre monitoring station are the highest in Europe. Concentrations are greater even than in Beijing, where expatriates have dubbed the city’s smog the airpocalypse.
It is the law of unintended consequences at work. EU efforts to fight climate change favoured diesel fuel over petrol because it emits less CO2. But diesel’s contaminants have overwhelmed the benefits from other measures that include a toll to drive in central London, a bike-hire programme and better public transport.
“Successive governments knew more than 10 years ago that diesel was producing all these harmful pollutants, but they myopically ploughed on with their CO2 agenda,” said Simon Birkett, founder of Clean Air in London.
“It’s been a catastrophe for air pollution, and that’s not too strong a word. It’s a public health catastrophe.”
Tiny particles called PM2.5s probably killed 3,389 people in London in 2010, the government agency Public Health England said last month. Like nitrogen dioxide, or NO2, they come from diesel combustion. Because the pollutants were found together, it was hard to identify deaths attributable only to NO2, said Jeremy Langrish, a clinical lecturer in cardiology at the University of Edinburgh.
“Exposure to air pollution is associated with increases in deaths from cardiovascular disease such as heart attacks and strokes,” Langrish said. “It’s associated with respiratory problems like asthma.”
London is not alone in having bad air in Europe, where 301 sites breached the EU’s NO2 limits in 2012, including seven in the British capital. Paris, Rome, Athens, Madrid, Brussels and Berlin also had places that exceeded the ceiling. The second and third-worst sites among 1,513 monitoring stations were both in Stuttgart, after London’s Marylebone Road.
“Nitrogen dioxide is a problem that you get in all big cities with a lot of traffic,” said Alberto Gonzalez Ortiz, project manager for air quality at the European Environment Agency (EEA) in Copenhagen. “In many cases it’s got worse because of the new fleets of diesel cars.”
The EU limits NO2 to a maximum of 40 micrograms per cubic metre of air. The concentration on Marylebone Road was almost 94 micrograms in 2012, according to the most recent data from the EEA.
The level for the site last year was 81 micrograms, and it was averaging 83 micrograms this year, according to King’s College.
In contrast, Beijing had a concentration of 56 micrograms last year, according to China’s Ministry of Environmental Protection.
Europe-wide policy triggered the problem. The “dieselisation” of London’s cars began with an agreement between car manufacturers and the EU in 1998 that aimed to lower the average CO2 emissions of new vehicles. Because of diesel’s greater fuel economy, it increased in favour.
EU rules enforced since 2000 allowed diesel cars to spew more than three times the amount of oxides of nitrogen, including NO2, as those using petrol. New rules that took effect in September narrow that gap.
“The challenge is much greater that we had thought just a few years ago,” said Matthew Pencharz, energy adviser to London Mayor Boris Johnson.
“A lot of that is due to a well-meant EU policy that failed. We’re stuck now with these diesel cars – about half our cars are diesel, whereas 10, 15 years ago, it was lower than 10 per cent.”