DEATHS FROM AIR POLLUTION IN YOUR REGION
On this map, you can see the estimated percentages of adult deaths attributable to particulate air pollution*
to cleaner forms of transport. From 2020, London will impose charges on vehicles entering a new Ultra Low Emission Zone that fail to meet tight emission standards. Meanwhile, a network of displays giving air quality alerts is already being rolled out across London’s bus routes, underground lines and major roads.
Other cities are going further, with diesel vehicles set to be banned from Paris, Madrid, Athens and Mexico City by 2025 under plans unveiled at a gathering of city leaders in December. But questions are already being asked about the effectiveness of such bans. A study of the impact of London’s existing low- emission zone found that three years after it was set up, there was still no sign of improvement in either air quality or the respiratory health of children.
There is also concern about a problem that has long dogged attempts to solve environmental problems: unintended consequences. Experts caution that banning vehicles from driving through city centres can simply shift the problem elsewhere – including into residential zones, where most people spend the majority of their time, and kids go to school.
Other measures for tackling pollution have run into similar problems. Tree-planting has long been regarded as an ideal solution to air quality along roads. Research suggests that trees can mop up oxides of nitrogen, while a recent report by The Nature Conservancy claimed that trees can absorb as much as 24 per cent of the particulate matter around them. But studies have also shown that trees give off their own pollution in the form of volatile organic compounds (VOCs). These can boost levels of ozone in the air and combine with other forms of pollution to affect vulnerable people, such as asthmatics.
The recent report by NICE went further, stating that trees can also slow air currents that would otherwise shift pollution: “It is not always true that trees reduce air pollution. Their effect is dependent on factors including species, canopy density, time of year and wind direction,” the report stated.
NICE also made headlines by pointing out that even traffic control measures like speed bumps can affect air quality, with vehicles accelerating after crossing them, releasing a cloud of pollutants.
Encouraging people to use their cars less could trigger unintended consequences. “Switching your urban commute from car to cycle will reduce overall emissions but probably increase your personal exposure to traffic pollution,” says Prof Richard Skeffington, an air pollution expert from the University of Reading. CLEANER CARS Many believe the only effective answer is the outlawing of diesel in favour of cleaner technology such as electric motors. Environmental pressure group Greenpeace is campaigning to get the UK government to ban sales of diesel cars in the UK.
But experts caution that this is no panacea, either. According to the Royal Colleges report, recent research has revealed a new source of road pollution: particles rich in toxic metals shed by brakes, tyres and road surfaces. “Even electric and alternatively fuelled vehicles can never be emission-free,” say the report’s authors.
The issue of air pollution may yet become a case study of the dangers of simple solutions to complex problems. Ironically, it was environmental concerns that sparked the surge in popularity of diesel engines in the first place. As they use fuel more efficiently, diesel engines emit less carbon dioxide than their petrol counterparts. Politicians keen to cut greenhouse gas emissions offered taxpayers incentives to buy diesel cars, whose numbers soared from 1 in 12 EU registrations in 1990 to over 50 per cent in 2010.
The adoption of diesel cars has had no measurable change in global warming – but air quality in cities across Europe has plunged. “Diesel engines are not the same as they were 20 years ago – they’re probably better,” says Frew. “But there are always unintended consequences, and we don’t know what we don’t know.”