Clean air or low emission zones are being rolled out in more UK cities. On 1 June, Birmingham will follow London and Bath by introducing a charge to deter highly polluting vehicles from the city centre.
The zones in Birmingham and Bath were delayed by Covid but these schemes are now needed more urgently than before. With new vehicle sales at record lows, older and more polluting vehicles are still on our roads rather than on the scrap heap where we expected them to be by now.
Lessons from London’s zone and the hundreds that operate in Europe counter many of the myths around these schemes.
First, the zones work, if they are sufficiently ambitious. London’s ultra-low emission zone (Ulez) reduced nitrogen dioxide by 37%, compared with roads far outside the zone. Following Sadiq Kahn’s re-election as London mayor, the Ulez will become 18 times larger.
Second, benefits do not start when the charge starts. For the Ulez, a 20% decrease in nitrogen dioxide came as taxis, buses and delivery vehicles were upgraded ahead of charging. Pre-scheme benefits were also seen when London first introduced a low emission zone in 2008. In Leeds, the pre-charging gains were thought to be sufficient and the zone was cancelled in 2020. It remains to be seen if benefits will be locked in without the charge.
Third, air pollution does not get worse outside the zone due to diverting vehicles. Instead the experience from London and cities in Germany show that the cleaner vehicles are also used in the surrounding area, spreading the benefit.
Fourth, it is often said that the zone charges unfairly penalise the least well off. In fact, poorer communities have most to gain. They experience worse air pollution than their richer counterparts but, when it comes to driving, they contribute less to the problem. Yes, placing charges on older vehicles would have more of an impact in poorer areas, but this effect is small: a 2019 study found that cars in the UK’s poorest areas were, on average, just over a year older than those owned by the most well off. This was due to multi-car households in wealthier areas and the age of their second, third and in some cases fourth cars.
Most zones are designed to help air pollution in city centres comply with legal limits. However, there is strong evidence that air pollution still causes harm at concentrations well below legal limits. We therefore need to go further and continuously improve air pollution for all communities.