Clean Air Zone likely to remain in Portsmouth until 2027
Portsmouth’s Clean Air Zone is likely to remain in place until 2027, even though the city has not exceeded legal limits for Nitrogen Dioxide.
Portsmouth City Council is required by the government’s Joint Air Quality Unit (JAQU) to implement plans to reduce air pollution when concentrations at the roadside exceed legal limits.
Nitrogen dioxide (NO2) is a highly reactive gas that can inflame airways, reduce lung function and immunity, and aggravate respiratory conditions like asthma.
JAQU’s initial assessment in 2023 showed three areas in the city exceeding the legal NO2 limit and nine others at risk. Council reports at the time suggested Portsmouth was “not on track to achieve success.”
To reduce NO2 levels as quickly as possible, as required by the government, the council implemented a Clean Air Zone (CAZ). This zone covers a south-western region stretching from Landport in the north to Somerstown in the south and Portsmouth Harbour to the west.
The CAZ charges buses, coaches, taxis, and private hire vehicles that do not meet Euro 6 emission standards for diesel and Euro 4 for petrol. Newer, cleaner vehicles are exempt.
However, a follow-up assessment by JAQU in January this year, confirming the city’s success for the 2025 calendar year, showed no exceedances at any of the 12 monitored locations, including those that previously exceeded the legal limit.
Despite this, the sites on Alfred Road and Hope Street are still considered “at risk of exceeding.”
The council will now undertake modelling for the third assessment at the end of 2026, which will factor in future developments and traffic data.
A council can remove its CAZ after passing the third assessment (demonstrating sustained success) and the fourth assessment (indicating success is likely to continue without measures).
If successful, the decommissioning is planned to take place in 2027.
Council reports add: “Despite improvements in pollution levels resulting in compliance of the CAZ, vehicle usage in Portsmouth still contributes to air pollution and from a public health perspective, there is no ‘safe’ level of air pollution.
“Therefore, the strategic focus remains on reducing traffic volume and generating mode shift.”