New air pollution data reveals promising start for Glasgow's LEZ

The latest Air Quality Annual Progress Report shows that nitrogen dioxide levels in the city centre and LEZ area had dropped by 20% compared to diffusion tube monitoring from the previous year.

The annual report is the first to consider pollution levels during LEZ enforcement following the scheme's full roll-out to all vehicle types on 1 June 2023.

Diffusion tube monitoring also showed a 15.3% drop in nitrogen dioxide concentrations at locations outside the city centre.

Airborne particulate matter and nitrogen dioxide are the main pollutants of concern in Glasgow, with the annual report assessing air quality so that pollution concentrations can be compared against legal requirements known as objectives.

In addition to diffusion tube monitoring, air pollution is also observed by eleven automatic monitoring stations around the city. Like the previous year, all stations recorded nitrogen dioxide concentrations below the legal objective, however 2023's results showed further decreases in levels of this pollutant.

Continuing the trend of full compliance since 2014, particulate matter monitoring met the objectives for PM10 as well as PM2.5 which are the ultra-fine particulates that are especially damaging to health.

Whilst these results are very promising, the 2023 data did however highlight areas of concern.

Diffusion tube monitoring on Gordon Street and under the Hielanman's Umbrella showed marginal exceedances of the nitrogen dioxide objective. And whilst all automatic monitoring stations showed compliance with the legal levels, the station on Hope Street only narrowly met the objective - a repeat of 2022's result.

As Glasgow's LEZ was in force for only half of 2023 and did not yet apply to zone residents or non-compliant taxis, it is too soon to determine its full impact on air quality. Initial results from monitoring however are highly positive and further improvements can be expected in future reporting.

Cllr Angus Millar, Convener for Transport and Climate said: "Air pollution contributes to hundreds of deaths in Glasgow each year, as well as exacerbating long-term health inequalities and the health conditions of thousands of Glaswegians.

"Glasgow's Low Emission Zone was introduced to address stubbornly high levels of air pollution in the city centre - and with Dundee, Aberdeen and Edinburgh now implementing their own LEZs, Scotland's cities have joined hundreds across Europe in taking this kind of action to improve air quality.

"The early progress recorded in Glasgow in 2023 - with a 20% drop in the city centre's nitrogen dioxide levels - is really encouraging. With some locations still showing breaches of legal limits, however, the impact of the LEZ's full roll out will only become clear with next year's annual monitoring data, and Glasgow will continue our work to seek cleaner, more breathable air that meets legal requirements."

Previous rounds of review and assessment has seen Glasgow declare four Air Quality Management Areas (AQMAs), where the objectives for nitrogen dioxide and particulate matter were not being met.

Three of these AQMAs have since been revoked - highlighting that improvements in air quality have continuously been achieved. The AQMA declared for the city centre however remains in place.

Whilst the LEZ is driving significant improvements in the city centre's air quality, revocation of an AQMA is only possible where there is compliance with the objectives for at least three consecutive years, and where further exceedances of the objectives are unlikely to occur.

Earlier this year Glasgow set out refreshed plans to tackle air pollution across the city. Whilst the updated Air Quality Action Plan takes a citywide approach, there remains a level of focus on the city centre due to its pollution levels remaining of concern.

The Plan's priority actions include:

• A review of air quality monitoring - with a focus around schools, hospitals and care homes.
• The continuation of vehicle idling awareness campaigns and enforcement.
• Supporting transport strategies which benefit air quality.
• Supporting the expansion of our active travel network.

Following public consultation, the action plan also now includes commitments to assess future developments that could impact on air quality, and to liaise with the Scottish Government as it continues its review of the statutory air quality objectives.

2024 Air Quality Annual Progress Report for Glasgow:

The 2024 Air Quality Annual Progress Report refers to data from the previous (2023) calendar year.

The report went before our Net Zero and Climate Monitoring Committee on 24 September 2024.  You can read the committee paper here.

As the LEZ was only in force for the last seven months of 2023 it is not yet possible to determine its full impact on air quality. It is also noteworthy that zone residents did not need to meet LEZ requirements until 31 May 2024 and non-compliant public hire taxis were eligible for a temporary exemption until the same date - with 776 exemptions issued to operators.

Initial results from 2023 are however positive, with significant reductions in the monitored levels of nitrogen dioxide recorded across the city and particularly within the area of the LEZ.