Clean Air Zone cut nitrogen dioxide but not fine particles, study finds

Birmingham's Clean Air Zone has produced "modest, but significant" reductions in one of the main air pollutants, but has had no detectable effect on the fine particles that are most harmful to health, according to a University of Birmingham study.

The study, published in August, found reductions in nitrogen dioxide of up to 7.3 per cent, but "no detectable impact in the concentrations of fine particles, PM2.5 - the air pollutant with greatest health effects".

How the zone works

The Clean Air Zone launched on 1 June 2021, the third in the UK after London and Bath. It covers the area inside the A4540 Middleway ring road, including the Jewellery Quarter, the Chinese Quarter, the main shopping district and the area around New Street station.

Drivers of vehicles that do not meet emissions standards are charged £8 a day for cars, taxis and vans, and £50 a day for lorries, coaches and buses.

A stronger claim from the council

The study's findings are more cautious than the council's own figures. The council has said nitrogen dioxide levels fell by 13 per cent during the first six months of the scheme, and that the number of polluting vehicles driving through the city centre halved.

In the month after the charge was introduced, the number of the most polluting vehicles entering the zone each day dropped from 18,787 to just over 11,000, and compliance rose from 73.8 per cent to 80.4 per cent.

Fines and revenue

Around 40,000 drivers a month were being fined for non-compliance at the start of 2023, down from around 50,000 a month a year earlier, although around 10,000 drivers in total have successfully appealed their fines.

In its first two years, the scheme raised £79 million in fees and penalties. Some of the money has been earmarked for green transport projects, including car-free school streets, better cycle paths and more 20mph zones.

Why Birmingham has a zone

The scheme gained momentum in 2017, when the European Commission warned Birmingham City Council to cut air pollution by 2020 or face a fine of £60 million. The Government approved the plan in 2019, but it was delayed by the pandemic.

It has always been controversial. Supporters, including the British Heart Foundation, argued that bold action on air quality was vital to protect people's health. Opponents said it would "turn the city into a ghost town", and some businesses have complained about the extra costs.

This month the Telegraph reported that the scheme was "piling extra costs onto small businesses", quoting entrepreneurs and residents affected by higher delivery costs.

The university study is likely to fuel continuing debate over whether the zone should be changed or extended to tackle fine particles as well as nitrogen dioxide.