Twenty miles per hour speed limits: a sustainable solution to public health problems in Wales

Identifying interventions that will impact positively on road traffic injuries and air quality, and encourage active travel, has been described as a significant public health challenge.

This paper set out to explore whether 20mph limits could be an effective intervention. The researchers reviewed the available evidence to identify the effect of 20mph limits on health and well-being, and then estimated the effect of a change to a 20mph limit on road traffic casualties and air pollution.

They estimated that between six and 10 lives would be saved and 1,200-2,000 casualties avoided each year, at a ‘value of prevention of £58–£94m’.

Published in the BMJ ‘Journal of Epidemiology and Community Health’, the research is authored by Public Health Wales’ Sarah J Jones and Huw Brunt.

The research concludes that a default 20mph limit is ‘the solution to increasing public health problems in Wales’, adding that road traffic injuries, air pollution and obesity are ‘an inter-related, interdependent triad’.

In terms of air pollution, the researchers estimate that deaths attributed to nitrogen dioxide (NO2) may increase by 63, and ‘years of life’ lost by 753. However, deaths attributed to particulates (PM2.5) – the mixture of solid particles and liquid droplets in the air – may decrease by 117 and years of life lost by 1,400.