Welsh Government M4 air pollution claim ignored fewer cars

On Monday, the Welsh Government announced that, since the schemes were introduced in 2018, they have made “significant progress” in lowering the levels of nitrogen dioxide in affected areas by “up to 47 per cent”.

Deputy minister for climate change, Lee Waters, who has a responsibility for transport said: “It’s clear that the speed restrictions we’ve introduced on our most polluted roads are working - the results speak for themselves – but compliance with these limits is essential if we are to achieve the reductions we need to make in the shortest possible time.”

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However, the minister did not mention how or if significantly lower traffic levels throughout last year as a result of the coronavirus lockdowns had contributed to the figures.

When asked by the Argus if it was misleading to omit this, a Welsh Government spokeswoman said: “The pandemic has had an impact on reducing the levels across all five locations but this alone does not explain the significant reduction in nitrogen dioxide levels measured.”

The Welsh Government was unable to provide data on the number of vehicles using the M4 at Newport, and how this was affected by the coronavirus lockdowns.

Air pollution levels in clean air zones in Wales. Data: Welsh Government.

According to the Welsh Government figures, the levels of air pollution on the M4 – between junction 24 for Coldra and junction 28 for Tredegar Park – had fallen by 6.77 per cent from when the 50mph speed limit was introduced in 2018 to 2019 – from 63.5 micrograms of nitrogen dioxide per cubic metre (µg/m³) to 59.2µg/m³.

However, in 2020, that figure fell to an average of 38.4µg/m³ – 39.53 per cent lower than in 2018.

In the other 50mph clean air zones, the A494 at Deeside saw the lowest reduction between 2018 and 2020 – with the concentration of nitrogen dioxide falling by 37.2 per cent.

READ MORE: Speed cameras on M4 haven't been turned on five months after being installed.

The M4 at Port Talbot saw a 41.74 per cent fall from the 2018 figure, while the A483 at Wrexham saw a drop of 45.22 per cent.

And the A470 at Pontypridd saw a 46.3 per cent reduction the mean concentration of nitrogen dioxide compared to in 2018.

In figures published in March 2020 in the Welsh Government’s plan for tackling roadside nitrogen dioxide concentrations, air pollution levels on the M4 at Newport were projected to fall from around 49µg/m³ in 2018 to 46.7µg/m³ by the end of 2019, and to 44.2µg/m³ by the end of 2020.

The Welsh Government said the speeding fines, which are to be brought in on the M4 at Newport from October 4, will lead to improvements in the air pollution levels across the clean air zones.

“The enforcement measures being introduced from October 4 will help ensure drivers continue to comply with the reduced speed limit so we can achieve improvements in air quality in these areas,” said a Welsh Government spokeswoman.