20mph limits massively cut toxic diesel emissions. 40,000 die early pa from outdoor fumes – 23 times more than in crashes. 20mph is equivalent to taking over half the petrol cars off the road. Traffic noise also blights lives. 20mph halves perceived noise compared to 30mph. We can’t see pollution, yet it affects our physical and mental health. Demand 20mph today!
Photo: BLF https://www.blf.org.uk/take-action/campaign/clean-air
Air Quality 38 % of UK cars run on highly polluting diesel. The Committee on the Medical Effects of Air Pollutants (COMEAP) estimates 29,000 ‘equivalent’ deaths pa from UK exposure to PM2.5 (particulates). Only a small fraction are from concentrations above legal limits. There are 40,000 early deaths due to fumes when Nitrous Oxides are included. Imperial College London found 20mph limits to improve air quality. Per 100 cars, 20mph was equivalent to taking 32 petrol cars off the road for particulates plus 30 petrol cars off for NOx. 20mph offers better air quality from traffic and emissions reductions. Put 20mph in air quality plans.
Noise research studies show about a 3 decibel (dB(A)) reduction with 20mph - perceived as halving ambient noise. Many people’s lives are blighted by road noise affecting sleep and mental health, with the poor most disturbed. Residents of heavy or fast traffic roads tend to live towards the rear of properties and avoid talking on the street, increasing risks of loneliness. 20mph turns streets into pleasant places.
A Swedish study on changes from 50 km/h (31mph) to 30 km/h (18.6mph) found reductions from 2-4 dB(A) for cars and 0-2 dB(A) for heavy vehicles. The maximum was 2 dB(A) less. In a German study, introducing 30 km/h zones to residential streets led to up to 3 dB(A) less. Another German study found the change from 50 to 30 km/h lowered 5 dB(A) the maximum level and 3 dB(A) the equivalent level. In Graz, speed limit changes decreased noise from 0.9 to 1.9 dB(A) on the equivalent level and 0.9-2.5 dB(A) on the maximum level. Bonanomi says that a 30 km/h limit (versus 50 km/h) has a reduction from 5-6 dB(A) of the peak noise level.
Rod King MBE said “The quickest, simplest way to cut road fumes and noise is to limit speeds to 20mph. Wide 20mph limits are proven to help us breathe cleaner air and hear each other better. The majority of UK’s largest urban authorities are already saying 20’s Plenty. It’s time to set this as a national standard. With the recent ClientEarth High Court ruling that the government is not meeting its legal duties on reducing pollution then maintaining dirty thirty limits on community streets cannot be allowed to continue.”