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20 is plenty!

The Welsh parliament, Senedd Cymru, have recently backed plans to reduce the speed limit in residential areas to 20mph in Wales. Newcastle Green Party Campaigner, Tay Pitman, has started a government petition to ask that the same is implemented in England too.

89% of all pedestrian and 83% of all cyclist casualties happen on urban roads. If average speeds reduce by just 1%, there’s a 6% reduction in the frequency of collision (1). A pedestrian hit by a vehicle at 20mph is twice as likely to survive than if they had been hit by a vehicle travelling at 30mph.

Air pollution levels will drop if urban traffic speeds are lower. Vehicles in 20mph zones move more smoothly with less stopping and starting, producing fewer particulate emissions; good news for people with respiratory illnesses such as asthma and COPD. But particulates aren’t the only pollutants affecting our health. Friends of the Earth recently reported that 1,352 locations across England that have breached nitrogen dioxide (NO2) levels (2); evidence shows that NOx emissions reduce when diesel vehicles are driven at 20mph. With up to 36,000 people in the UK dying prematurely each year from long term exposure to air pollution (3), it’s clear that we must take action to improve public health.

Background research carried out into the possible impact of introducing a default 20mph speed limit in Wales, found that it could result in reducing transport emissions in residential areas by 12% and that “road traffic injuries, air pollution and obesity are inter-related” (4). When our roads are safer to travel on and the air there is cleaner, people are more inclined to use alternative modes of transport such as walking and cycling. As a result, people’s physical and mental health improves further; a win-win situation.

Reducing the speed limit to 20mph in residential areas will make our streets safer for people, whether walking, cycling or driving. Noise pollution will be reduced, improving the quality of life for residents. Air pollution will be reduced, helping not only people, but will impact upon climate change too. For the sake of people and planet, 20 is plenty!


1. Taylor, M. C., Lynam, D. A. and Baruya, A. (2000), TRL Report 421 – The Effects of Drivers’ Speed on the Frequency of Road Accidents. Crowthorne: TRL Transport Research Laboratory (2004), Published Project Report 025 – Accident Analysis on Rural Roads: A Technical Guide. Crowthorne: TRL
4. Jones SJ, Brunt H, Twenty miles per hour speed limits: a sustainable solution to public health problems in Wales, J Epidemiol Community Health 2017;71:699-706.