NICE Recommends 20mph limits Without Traffic Calming to Improve Air Quality

NICE recommends urban speed reduction for better air quality. NICE guidance says 20mph limits without physical measures in urban areas help “avoid unnecessary acceleration and deceleration”.

NICE, the National Institute for Health and Care Excellence, reviews evidence on health policies. It has published guidance on Air pollution: outdoor air quality and health in June 2017[1] which strongly supports 20mph limits for smooth driving and speed reduction. It advises authorities to set

“20 mph limits without physical measures to reduce speeds in urban areas where average speeds are already low (below around 24 mph) to avoid unnecessary accelerations and decelerations”

Many authorities have additionally set 20mph speeds on roads with higher than 24mph average speeds for consistency of limits across a community.

20mph limits are increasingly recognised as an affordable tool to tackle air quality action areas. Edinburgh, Glasgow, Hammersmith and Fulham and others have justified their wide area 20mph limits both on health grounds from fewer casualties, and due to reduced acceleration and encouraging modal shift away from car use towards non-polluting methods like walking and cycling – which all improve air quality.

NICE further states

“Where physical speed reduction measures are used to reduce road danger and injuries (20 mph zones – see NICE's guideline on unintentional injuries on the road), consider using them to encourage drivers to maintain a reduced, steady pace along the whole stretch of road, rather than road humps that may increase acceleration- and braking-related emissions”

Rod King MBE, Founder of 20’s Plenty for Us said:

“Many authorities recognise that 20mph helps them to both meet their air quality as well as ‘duty of care’ responsibilities to the vulnerable[2]. In fact switching to a 20mph limit makes a significant reduction in the most dangerous NOx and PM¹⁰ emissions[3]. It is entirely appropriate for NICE to make this recommendation to direct local authorities in their statutory duty to improve air quality and public health.”

[1] https://www.nice.org.uk/guidance/ng70

[2] http://www.20splenty.org/duty_of_care_mandates_20mph

[3] http://www.20splenty.org/emission_reductions

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Rod King commented 2017-07-29 18:48:43 +0100
The most important thing is to be consistent. If you do something in only one place to physically reduce speeds then at the same time you are communicating that elsewhere you can and should go faster. Engineering is fine if you can do it throughout the whole network of community roads. But is the affordable or practical? Other routes to gain compliance can be engagement, enforcement. Society has a choice, carry on curbing walking and cycling from fear of traffic danger or subject non-compliers to the rule of law. Its not difficult, simply needs commitment to supporting communities and the levers to better public health, air quality, child and elderly mobility, etc.
Matthew Hamar commented 2017-07-29 17:14:57 +0100
I can understand the logic but message needs to be clear that improved highway design is needed to help reduce speeds and improve safety. Whist this may not be traditional stop start measures, it would be narrowing of roads to create environment where drivers naturally go slower.