London has a dirty secret: Levels of the air pollutant nitrogen dioxide (NO2), as measured by a monitoring station in the central city, are the highest in Europe. Concentrations of the compound are greater even than in Beijing, where smog alerts are common.
The European Union’s fight against climate change has favored diesel over gasoline, because diesel engines burn fuel more efficiently and emit less carbon dioxide (CO2), the leading cause of global warming. But a byproduct of burning diesel is NO2. “Successive governments knew more than 10 years ago that diesel was producing all these harmful pollutants, but they myopically plowed on with their anti-CO2 agenda,” says Simon Birkett, founder of Clean Air in London, a nonprofit. “It’s been a catastrophe for air pollution, and that’s not too strong a word.”
The World Health Organization says NO2 is linked to asthma and can inflame respiratory passages and aggravate bronchitis in children. In addition to NO2, diesel combustion also generates easily inhaled fine particulate matter, which probably killed 3,389 people in London in 2010, the government agency Public Health England said in April. Because the fine particles and NO2 commingle, it’s hard to distinguish deaths caused only by NO2, says Jeremy Langrish, a clinical lecturer in cardiology at the University of Edinburgh. But researchers think NO2 has harmful effects independent of particulate matter, says Frank Kelly, a professor of environmental health at King’s College London.
The EU’s NO2 limit—a maximum of 40 micrograms per cubic meter of air—was breached at 301 sites in the EU in 2012, including seven in the British capital. The concentration on Marylebone Road, near Regent’s Park, was almost 94 mcg, according to the European Environment Agency (EEA). The level for the site in 2013 was 81 mcg, according to King’s College London. Beijing had a concentration of 56 mcg of NO2 last year, says China’s Ministry of Environmental Protection, though it has almost triple the particulate pollution of London.
According to the EEA, districts in Athens, Berlin, Brussels, Madrid, Paris, and Rome also exceeded the ceiling. The second- and third-worst sites were in Stuttgart. “It is a problem that you get in all big cities with a lot of traffic,” says Alberto González Ortiz, project manager for air quality at the EEA. “In many cases it’s gotten worse because of the new fleets of diesel cars.”
The switch to diesel began with an agreement between carmakers and the EU in 1998 to lower the average CO2 emissions of new vehicles. Because of diesel’s greater fuel economy, car companies chose to make more diesel-powered autos. EU regulators say this switch was not their doing. The European Commission, the EU regulatory arm, “is and always has been technologically neutral,” says Joe Hennon, a spokesman. “It does not favor diesel over petrol-powered cars. How to achieve CO2 reductions is up to member states.” EU rules enforced since 2000 allowed diesel cars to release more than three times the amount of nitrogen oxides, including NO2, as gasoline cars. New rules narrow that gap.
NO2 and the particulates emitted by diesel-burning engines are insidious, because they’re not as visible as the pollutants of the past. London’s air has improved since the pea-soup fogs of the 1800s and 1900s. In 1952, the Great Smog killed 4,000 people. East Londoners couldn’t see their feet through a choking blanket of smoke caused when cold air trapped factory emissions and coal fumes. That led to passage of a clean-air law in 1956. As a result, “there isn’t the same pressure on politicians” as in the 1950s, says Joan Walley, a Labour Party lawmaker who leads Parliament’s cross-party Environmental Audit Committee. Walley’s committee began an inquiry on May 2 to assess government efforts to improve air quality.
“The challenge is much greater than we had thought just a few years ago,” says Matthew Pencharz, environment and 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 percent.”