News and Info from Deeside, Flintshire, North Wales

Welsh Government release report showing A494 speed limit reduction has seen NO2 emissions cut

A controversial 50mph speed limit on the A494 has seen harmful emissions reduce according to transport minister Ken Skates, with a report now released backing up the conclusions.

The Welsh Government introduced 50mph speed reductions on five 70mph stretches of road in Wales where nitrogen dioxide (NO2) emissions were found to be above the legal limit as set out by an EU directive.

The reduced speed limits were introduced at each of the locations as “research demonstrated the potential to bring immediate improvements to air quality, and bring forward compliance” the Welsh Government said.

Average speed cameras have also been installed locally in a bid to enforce the 50mph speed limit, they became operational for monitoring last month.

As Deeside.com reported on Friday Ken Skates AM revealed at a school visit in Shotton that an interim data report on the first 12 months of the 50mph speed limits being introduced – to be published yesterday – has shown a reduction in NO2 levels.

The reports, dated September 2019 confirm the current levels of NO2 concentrations on the Welsh Government Motorway and Trunk Road network at five sites. It provides the data from December 2017 to July 2019, so historic information and data under the 50mph limit, although not under the camera enforcement period as that has only gone live recently.

The report summarises, “…initial indications are positive that the NO2 concentrations have reduced at the five sites from December 2017 to July 2019”, and with regards to speed, “Speed profiles demonstrate that mean speeds are above 50mph for all five sites, however, it is expected that with the Average Speed Cameras now in place at four of the sites, compliance will be improved with the 50mph speed limits.”

There are no plans to remove the measures in place, with the report noting “Until additional information is obtained and the trends remain positive, it is too early to make firm conclusions or any other recommendations to remove the measures that have been either implemented or proposed at the five sites.”

Concentrations of NO2 at the roadside at each of the five sites have been recorded via a series of triplicate diffusion tube since mid-December 2017 and the data has been used to help establish the effect that the measures have had on NO2 concentrations.

To help obtain a more accurate picture on concentrations, the report states the tubes were supplemented with continuous reference method analysers in August 2019. Data from these analysers has not been included in the report but will included within subsequent reports.

Data from the report is copied below, with NO2 concentrations in μg/m3 recorded via the diffusion tubes during the 6-month period prior to the introduction of the 50mph speed limits in June 2018. It is stated data has been averaged for the year and corrected for seasonal variations using national bias adjustment factors.


The below details the NO2 concentrations recorded in the 12-month period following implementation of the 50mph speed limits in mid-June 2018.


The report also has a separate dataset, showing a summary of mean traffic speeds following their initial implementation in June 2018 to August 2019. The A483 by Wrexham shows a mean speed of 57mph against the 50mph limit, with the A494 in Deeside having a mean speed of 58mph.

The report concludes with graphs showing the various data sets for each site, indicating the readings are still above EU limits.

Speaking to Deeside.com, Ken Skates AM said: “I am encouraged by these findings in the first year of these speed limits, but it is vital we continue to reduce emissions in order to save people from the risk of developing potentially serious health conditions.

“We believe that as a result of putting the average speed cameras in, we will see a further reduction in nitrogen dioxide.

“Most motorists would make a responsible choice, the selfless choice, do you want to save 54 seconds by driving at 70 miles an hour rather than 50 miles an hour, willingly and knowingly contributing to maximum dioxide levels that could shorten the lives of people nearby?

“I think responsible motorists would appreciate that spending one minute more in that car to cut nitrogen dioxide poison to below a dangerous level is a responsible thing to do.”

Critics of the 50mph speed limit have pointed to the emissions from heavy industry close to the A494 as a major contributing factor to pollution along the route, Mr Skates said:

“There are public health watchdogs in place to make sure that they don’t emit dangerous levels of pollution.

Until now, we haven’t had a similar protective arrangement in place for roads.

Whilst we’re seeing a huge reduction in the amount of emissions from factories, and from other contributing factors such as power generation, we’re not seeing that reduction on the roads.

And so for the short term, at least, whilst we undergo the transition to ultra low emission vehicles we need to do something to cut the amount of poison that is affecting the kids that live nearby.

And I think most reasonable people would recognise that in order to prevent children from developing really serious health problems. It’s okay to spend another minute on the road.”

The Welsh Government says that more data will be required to assess “if this improving air quality trend can be confirmed.”

A further report is due to be published in March 2020, with the speed limits remaining in place until the levels of nitrogen dioxide drop and remain below the legal limit.

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