Welsh roads to get 50mph limit to improve air quality

Published 08 May 2018

The Welsh Government has unveiled proposals for 50mph speed limits for motorways and major A roads, as part of a £20m package of measures to improve air quality.

Air pollution is thought to cause more than 2000 deaths in Wales every year and a consultation has been launched on plans for Clean Air Zones. The Minister for Environment, Hannah Blythyn, has outlined a £20m fund. Local authorities will also get powers to stop or restrict the most polluting vehicles from entering Clean Air Zones. 

Temporary 50mph speed limits will come into force within the next two months to reduce harmful nitrogen dioxide (NO2) levels. The new speed limits will be introduced at five locations:

  • A494 at Deeside
  • A483 at Wrexham
  • M4 between Junctions 41 & 42 (Port Talbot)
  • M4 between junctions 25 & 26 (Newport)
  • A470 between Upper Boat & Pontypridd

The RAC’s head of roads policy Nicholas Lyes has said it’s questionable whether reducing the speed limit to 50mph on two stretches of the M4 in Wales which are regularly subject to major jams is likely to make a difference to harmful nitrogen dioxide levels.

“Slowing down traffic can help to improve flow, but if there are simply too many vehicles for the road space, then jams are still likely to occur so this is as much a question of capacity as anything else,” commented Lyes.

“The issue affecting these two areas, which are both close to urban areas, must be solved in the long term not just temporarily, if indeed the speed limit reduction has the desired effect.”

In January 2018, the Welsh Government was taken to the High Court by ClientEarth over its failure to address NO2 levels in towns and cities that exceed EU law. Since then the Welsh Government has pledge to work with environmental groups to improve air quality. A new Air Quality in Wales website has also been launched, making it easy for people to check live air quality information for their area. 

The Minister for Environment said she was “confident" the measures would deliver cleaner air and cut the public's exposure to airborne pollutants.


retiredspeedmerchant    on 9 May 2018

Will simply cause more pollution!

conman    on 14 May 2018

Yet another knee jerk reaction by politicians reacting to some idiotic Green person, do they not know that pollution is caused by the work the engine is doing, so a car that travels along at 2000 rpms is polluting less than a car that is doing 2500 revs never mind the speed. My car will now cause the same amount of pollution in Wales than in England. In 6th gear at 70mph = 2000 rpm, At 50 mph = 2000 rpm in 4th I have to keep the revs up on a run as the DPF filter will not re generate. Why doesn't anybody think before they make decisions and they will not recind these stupid laws as they will then have been see to wrong in the first place.

NickNike    on 14 May 2018

at a lower seed, the drag will be less so youn burn less fuel.

conman    on 14 May 2018

If anyone wishes to respond to the proposals being made by the Welsh government.
you have been given a chance to air your views on the 50 mph limit. and air quality.



the response tag is at the bottom of the page.

   on 14 May 2018

Came across this interesting batch of stats which, without having to be a statistician, will help you make up your mind about this "40,000 deaths a year" business. This would also impact the idiotic Welsh decision re 50mph. Beyond parody really.


If Welsh (or any other people) stopped smoking, excess drinking, ate healthily, took some exerise etc there could be far more significant health effects in my view.

MGBGTLE    on 14 May 2018

At higher speeds, overcoming wind resistance tends to be the greater part of the work an engine has to do. The resistance increases in proportion to the cube of the wind speed. So, increasing the speed from 50mph to 70mph means that the engine has to work about 270% more to overcome that extra wind load.

MGBGTLE    on 14 May 2018

Just to clarify by an example: Suppose and engine needed to produce 10 horsepower to overcome wind resistance at 50mph, then it would have to produce about 27 horsepower at 70mph but the ground is only being covered 1.4 times as fast, so nearly twice the energy per mile would be required, hence an increase in fuel consumption and exhaust emissions per mile.

Edited by MGBGTLE on 14/05/2018 at 16:14

RJP41    on 14 May 2018

Its the same old thing office pen pushers and politicians who have no idea in the real
world trying to win votes to make it look like they are helping and think they know best we will soon have a man with red flag walking in front.
Engines run more efficiently and cleaner at a constant speed slowing down and speeding up or sitting in a jam adds inefficiency and pollution.
I would like to know where all these thousands of deaths caused by car pollution that have been banded around more recently came from no doubt a tree hugger ,or some of these weird protesters at demos etc who never seem to work or travel ?.

   on 14 May 2018


Old Smokey    on 14 May 2018

Diesels pollute more at light load than heavy. When the air/fuel mixture explodes in the cylinder, some of the oxygen burns the fuel; the rest combines with the nitrogen to make NOx. The harder the engine is working, the fuel consumes more oxygen, leaving less to combine with nitrogen. (Unlike a petrol engine, where the air is metered to supply only enough oxygen to burn all the fuel.)

This means that reducing speeds to 50mph, which reduced air resistance and so forth, will INCREASE NOx. It would only save if it cuts traffic jams - a diesel is worst when idling, which is why stop/start technology is a "good thing", and why you should stop your engine in a jam.

Alroya    on 14 May 2018

Speed limits cause congestion as they do in Portalbot and Newport now, which means more cars in less space causing more pollution.

   on 14 May 2018

They have had the 50 mph at Port Talbot for some time. usually you can only go through this section of motorway at 30 mph anyway so 50 mph would be a bonus! At this section of motorway there are several short slip roads on and off over a short distance so the reduced speed limit is sensible from the view of preventing accidents.

S Rolfe

NickNike    on 14 May 2018

Diesels are the problem and they were never suited to auto use. Just get rid of diesel cars.

Husbandofstinky    on 15 May 2018

Pointless posting.

Euro 6 diesels emit almost the same levels of Nox compared to the equivalent petrol model

Quite a good tool


Ball park about 5% more.

Flipping it around, petrol emit a similar level in excess of CO2

So pick your poison.

Many hybrids also produce a high level of toxicity as highlighted by a recent which study. On top of that the destruction and carbon footprint caused throught lithium mining alone.

Diesels are great in what they do - long distances and towing. Get the right tool for the job.

Here the issues is infrastructure and lack of investment.

gordonbennet    on 15 May 2018

On those sections the chances of travelling at more than 50mph at any normal time of day are slim to say the least.

Is there a budget of some sort that might be lost if they don't find something to waste it on.

   on 16 May 2018

Deaths due to pollution, I wonder!
Go back 70 years very few cars, mostly petrol, how many people lived to the newly introduced, retirement age, 65 for men 60 for women. I believe it was between 5 and 10 % of the population. Maybe ( tongue in cheek) pollution saves lives by killing germs.
People are living much longer now than 70 years ago, people have to did eventually, the air is so much cleaner now even though there are more cars.
Could global warming also be accounted for by there being less pollution so more of the suns energyis now reaching the earths surface?
Some people will remember the cold winters after all the dust polluting the atmosphere after nuclear bomb testing after the Second World War, until the test ban treaty.

conman    on 31 May 2018

The figure of 40,000 people was raised by a panel set up by the Government consisting of, people from the pharmaceutical industry, the chairman was Ceo of an asthma drugs firm, the deputy was working for Pfizer and most of the other members had interests in the asthma charity's. Just read the report yourself, you couldn't make it up. So guess what the outcome was now more people get Asthma drugs which these people have interests in and jobs.
I suppose it is the same as last nights BBC programme about the doctor that is trying to improve peoples lives by natural means not drugs. On depression and anxiety. The results actually if read properly say that the placebo tablets had virtually the same affect as the drug companies tablets, disgusting. Also the instance of babies becoming milk intolerant was highlighted when it was found that the so called independent discussions were sponsored by the major manufacturers of replacement milk products some costing 10x the price of normal baby milk and there was no real proof it worked. The sooner people wake up to the fact that major organisations are running the country the better. Not the government. The other point people may die from NOx and other pollutants but the world will die if the Co2 levels reach danger levels. Whether you drive diesel, petrol, hybrid or electric cars.

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