Has 50mph speed limit made a difference to Newport M4?

FIVE years ago the Welsh Government was taken to court by an environmental campaign group and conceded their handling of air pollution was unlawful.

Given six months to sort a plan, ministers took the step - unpopular among some - of trialling a slower speed limit on select stretches of road, and declared five permanent 50mph zones in June 2018.

Two M4 corridors were affected by the change: between junctions 25 and 26 in Newport, and junctions 41 and 42 in Port Talbot.

Wales became the first country in the world to officially declare a climate emergency in April 2019.

Climate was the emergency before Covid

In March 2021, the Welsh Government extended the limit, enforcing an average 50mph speed limit between junction 24 at the Coldra and junction 28 in Tredegar Park.

But it wasn't until November 2022 that cameras started to identify speeding vehicles and the first fines were issued for breaching 50mph.

What is the problem with air pollution in Wales?

According to a recent estimate from Public Health Wales, long-term exposure to air pollution causes the equivalent of 1,000 to 1,400 deaths in Wales each year.

Research has also shown a link between deprivation and pollution, which means people with a lower socio-economic status are more likely to suffer the health effects of bad air.

“We understand that speed limits may be unpopular,” read a Welsh Government statement from the time. “However, we know they are likely to be the quickest and most effective way to reduce NO2 levels.”

NO2 (nitrogen dioxide) is a gas that can irritate our bodies, make breathing more difficult, worsen diseases like asthma and cause people to develop illnesses as serious as heart disease and lung cancer.

UK regulations say annual mean NO2 levels should not exceed 40 micrograms per cubic metre. 

Has the 50mph speed limit made a difference?

The good news is that the annual mean NO2 levels recorded at junction 25 have not exceeded that level number since 2018.

There has been a marked drop in NO2 since the 50mph limit was first imposed. The impact of Covid travel restrictions is also impossible to miss with the annual mean for 2020 as low as 28μg/m3.

But since 2020, the NO2 levels at junction 25 have crept back up, though not as high as they were pre-pandemic.

A Welsh Government spokesperson said: "As traffic levels have increased, close to pre-pandemic levels, there has been an increase in the concentrations of NO2 recorded. However, this has resulted in only a relatively small increase in recorded concentrations at the Newport M4 junction 25 monitor, and these remain within the statutory limit value at this site.”

What about ozone?

You may remember being taught about holes in the ozone layer but it doesn’t form such a major part of the conversation today.

The ozone layer, around 10 to 20 miles above the ground, gets its name from ozone molecules, which absorb the Sun’s most harmful rays.

Although life on Earth depends on ozone in the atmosphere, scientists still monitor its levels nearer the ground because of the effect it can have on our health. Ozone inhalation can cause lung irritations, decrease lung function and increase the occurrence of asthma attacks.

The ozone levels at junction 25 have been higher since the pandemic, which could be at least partly caused by the lower concentration of NO2.

Hot summer weather can also correlate with higher concentrations of ozone in the air.

Because of the number of unknown factors – not least the Welsh weather – it is hard to predict how the air quality in Newport might change in coming years.

The Welsh Government spokesperson said it was “difficult to forecast” future levels because of factors such as weather and seasonal effects, but a detailed report on the last calendar year will be released soon.

What do residents say?

Cleaner air can only be a good thing for public health.

Slower speeds should also mean lower noise levels in Brynglas, St Julians and other areas straddling the M4 - but some residents say there has been no discernible change since the 50mph limit came into force.

Emmanuel Lewis has lived on Heather Road, within earshot of the M4, for 35 years. He says the 50mph zone has turned the noise into “more of a constant drone” but that the reduced speeds through Newport made it more difficult for driving.

“The trouble is with the 50mph zone is everybody bunches up,” said Mr Lewis. “People come up to it at 70mph and slow down suddenly, and that’s where you get the bunching up.”

Emmanuel Lewis of Heather Road (Image: Sam Portillo)

“I used to drive to Cardiff often, and you had to be in lane one by the time you got to the 50mph zone in rush hour otherwise you just couldn’t come off.”

Mr and Mrs Knight also live in St Julians, Newport, near the M4.

“You can hear the motorway where we are,” said Mr Knight.

“It depends which way the wind’s blowing!” added Mrs Knight.

Mr and Mrs Knight (Image: Sam Portillo)

They feel that electric bus services have made more of a difference to the environment in St Julians than any changes on the motorway.

What do opponents to the 50mph limit say?

The Welsh Conservatives have vehemently opposed the default speed limit drop to 20mph and also criticise the 50mph zones on the M4.

“Climate change policy is important, but it needs to be brought about in the correct way, and not rushed through for the sake of box ticking,” said Natasha Asghar, regional MS for South Wales East.

“We should not be forcing people to abandon their cars by ensuring Welsh roads are gridlocked with heavy traffic. This section of the M4 has always been extremely busy and the 50mph speed limit cameras have failed to tackle congestion in the area – which is what they were initially installed for.

Ms Asghar claimed the Welsh Labour government “wasted” taxpayer cash on the M4 relief road before shelving the project which the Welsh Conservatives have long campaigned to make happen.

“Labour rushing through policies to force motorists off the road simply does not work without viable alternatives, and as things stand those aren’t in place with the Metro project still years away from completion and an unreliable rail network.

“Top quality roads are a necessity not just for a strong economy, but for the incoming switch to electric vehicles and for a fully functioning bus system.”