Government action can cut air pollution, a long-term study has shown, with early deaths linked to dirty air in the UK falling by half between 1970 and 2010.

But toxic air remains the number one environmental health hazard, with one in 20 deaths still attributable to small particle pollution alone. The researchers said urgent action was needed to deal with a public health emergency that caused harm comparable to alcohol.

Cleaning up power stations and vehicles led to a fall in most pollutants in the four decades analysed. But ammonia from farms, which mixes with city air to form dangerous particles, has yet to be stringently tackled, the scientists said, and ozone pollution has risen.

“The message is that air quality policies work, but at the same time the current burden of air pollution on health is still very, very substantial,” said Sotiris Vardoulakis of the Institute of Occupational Medicine in Edinburgh, one of the research team. “It is a public health emergency and we need to do something about that.”

Even though air pollution has been falling over the years in the UK, understanding of the damage it causes to health is growing rapidly. A recent review found air pollution may be damaging every organ and virtually every cell in the human body, affecting physical, mental and reproductive health.

In October, the head of the World Health Organization said dirty air was the “new tobacco”. In the UK, the main air pollutants are above legal or WHO limits in most urban areas, although experts agree there is no safe level.

The research, published in the journal Environmental Research Letters, used pollutant emissions data and modelling to calculate the concentration of air pollution across the UK over four decades. Researchers took account of variations caused by the weather, so the results showed the impact of clean air policies.

Sulphur dioxide, a cause of acid rain, fell most sharply after coal power stations were targeted. More recent falls in small-particle pollution and nitrogen dioxide (NO 2 ), which are produced by cars, track the rise of stronger European Union vehicle regulation. This has had an impact despite the widespread cheating by carmakers exposed by the Dieselgate scandal.

The researchers found the proportion of all deaths attributable to small particle pollution fell from 12% in 1970 to 5.2% in 2010. The deaths linked to NO 2 fell from 5.3% to 3.0% over the same period. The health impact remains at levels similar to 2010 today, with small particles and NO 2 causing an estimated 36,000 early deaths a year.

Prof William Collins of the University of Reading, who was not part of the research team, said the fall in pollution was a success story. However, “these past policies focused on the ‘low-hanging fruit’ and further improvements in mortality will be more challenging”.

The environment minister Thérèse Coffey said: “We have taken huge strides in tackling air quality over the last 40 years. But we know there is a lot more to do. We have clear plans in place to tackle roadside nitrogen emissions and agricultural ammonia and are working to accelerate progress.”

The government’s latest clean air strategy was produced after the high court declared earlier plans illegal three times in succession. The government’s own research shows that charging people for driving polluting vehicles into urban centres is the most effective measure, but ministers have said this should be only a last resort.

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Vardoulakis said enabling more people to walk, cycle and use public transport more would make a big difference, and bring additional benefits. “These improve physical and mental health, and reduce the greenhouse gas emissions” that are driving the climate crisis.

Phasing out petrol and diesel cars in favour of electric vehicles is also important, though ministers have set a later date for this than some other countries.

Mathew Heal of the University of Edinburgh, one of the research team, said eating less meat would also help. “It is generally accepted that meat production requires a lot more energy and nitrogen emissions.”

He said the study gave confidence that pollution-reduction policies worked. “People have to make sacrifices sometimes to fit in with legislation and it is good to tell the public that some of those sacrifices are having a benefit.”

A significant amount of air pollution blows in from other nations. For example, 40-50% of small particles come from overseas, mainly France, Germany and the Benelux countries, and from shipping. Many UK air quality regulations derive from EU rules.

“International cooperation will be needed to give people in the UK truly clean air to breathe,” said Collins. The situation after the UK leaves the EU is unclear, according to Heal: “What happens after Brexit? Who knows?”