Reducing speed limits to 20mph on residential roads across Scotland will cut air pollution and save lives, according to medical experts and environmentalists.

Heart and lung charities have backed a new Sunday Herald campaign to introduce 20mph limits as the default in urban areas. Any move to improve air quality would benefit the health of hundreds of thousands of adults and children, they say.

Evidence suggests that slowing down cars from 30mph to 20mph can lead to less acceleration and deceleration, resulting in lower toxic exhaust emissions. Studies have also found that 20mph zones reduce congestion, and hence pollution.

The Sunday Herald revealed in January that air pollution from vehicles breached legal safety limits on 14 streets in eight cities and towns during 2016. We have also reported that the lack of 20mph limits on thousands of streets around the country had made the dangers of death or serious injury from road accidents into a “postcode lottery”.

The Scottish Greens environment spokesman, Mark Ruskell MSP, is planning to bring a bill to the Scottish Parliament to cut the normal speed limit in residential areas from 30mph to 20mph. “Air pollution is causing poor health and early deaths,” he said.

“Reducing speed in built up areas has been shown to cut the pollution from diesel vehicles that can trigger heart attacks and gives many people difficulty breathing.”

Ruskell welcomed the backing of health experts. “A 20mph limit is a low cost measure that not only reduces exhaust pollution but also makes streets more attractive for walking and cycling,” he argued.

“It’s not a silver bullet but a 20mph limit is a vital first step in making our communities safer and healthier.”

Environmentalists say that air pollution kills 2,500 people a year in Scotland. It is known to increase the risks of heart attacks and strokes, and to worsen lung diseases such as asthma.

According to the British Lung Foundation, Glasgow has the highest death rate from lung disease in Britain, 89 per cent above average. The city also has a high rate of fatal heart disease.

The twelve councils with the worst lung and heart disease records also include West Dumbartonshire, North Lanarkshire, East Ayrshire, Inverclyde, South Lanarkshire, Renfrewshire, Dundee and Aberdeen.

Head of the British Lung Foundation in Scotland, Irene Johnstone, pointed out that Scotland had some of the highest rates of lung disease in the UK, particularly in cities and urban areas. “Exposing Scotland’s children to polluted air will only make this worse,” she said.

"Research shows that as well as affecting children with conditions such as asthma, everyday exposure to pollution has even been found to contribute to breathing problems in healthy children.”

Air pollution worsened the symptoms of people with lung conditions, and could force them into hospital, Johnstone warned. "It’s not just about deaths,” she added. “It’s impacting on people’s quality of life and increasing the burden on our health services. That’s why the British Lung Foundation is committed to supporting initiatives that can improve Scotland’s air quality.”

Research funded by the British Heart Foundation at the University of Edinburgh has shown that air pollution can have a major impact on those with heart disease. “It can make existing heart conditions worse and increase the risk of a heart attack or stroke,” said the foundation’s director in Scotland, James Cant.

“We support any efforts to reduce levels of air pollution as this can help improve quality of life for the 670,000 people across Scotland living with cardiovascular disease.”

The campaign for 20mph speed limits has also been supported by Friends of the Earth Scotland. “20mph limits are a life-saving intervention and one of several measures which are required to deliver clean air,” a spokeswoman said.

“20mph limits have been proven to reduce accidents and injuries, traffic speed and volume, and improve safety. Less traffic on the road means cleaner air, and safer streets enable more of us to choose to walk, cycle, and enjoy healthier outdoor environments.”

The Scottish Government has said that it has “no current plans” to lower the national speed limit from 30mph to 20mph. But it has promised to consider Ruskell’s bill when it is brought forward.

TABLE

Local authorities with high death rates from lung and heart disease

council / increased likelihood of death from lung disease / heart disease death rate per 100,000

Glasgow City / 89% / 365

West Dumbartonshire / 61% / 377

North Lanarkshire / 57% / 356

East Ayrshire / 45% / 363

Inverclyde / 40% / 332

South Lanarkshire / 39% / 330

Renfrewshire / 37% / 340

North Ayrshire / 35% / 333

Dundee City / 34% / 325

West Lothian / 33% / 337

Aberdeen City / 20% / 352

South Ayrshire / 20% / 341

source: British Lung Foundation and British Heart Foundation