Glasgow's LEZ Reduces Nitrogen Dioxide Levels By 20% In 2023

New air quality data for 2023 shows encouraging results for Glasgow's Low Emission Zone (LEZ).

The latest Air Quality Annual Progress Report indicates a 20% reduction in nitrogen dioxide levels in the city centre and LEZ area, based on diffusion tube monitoring from the previous year.

The report marks the first assessment of pollution levels since the full enforcement of the LEZ, which expanded to all vehicle types on June 1, 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."