TREES in Bournemouth and Poole have saved taxpayers nearly £10 million a year, according to the Office for National Statistics.

A study for the ONS claims that in 2015 the NHS avoided £9.4 million in health costs thanks to air quality improvements by natural vegetation in the conurbation. That's £13.71 for every resident.

And in Dorset vegetation has saved £6.1m, the data shows, or £14.55 for every resident.

Nationally, the ONS estimates there were 7,100 fewer lung and heart-related hospital admissions, 27,000 fewer life years lost and 1,900 fewer premature deaths thanks to the service provided by nature, a saving for the whole of the UK of around £1 billion.

Professor Paul Cosford, director of health protection at Public Health England, said: "Air pollution is a growing threat to the public’s health, evidence shows it has a strong causal association with coronary heart disease, stroke, lung cancer and childhood asthma."

And Karen Exley, head of the health body’s air quality group, said: "Long-term exposure to particulate matter is known to be a contributory factor in early deaths, particularly for people with cardiovascular and respiratory disease, and is estimated to have an effect equivalent to 29,000 deaths a year in the UK.

"Long-term exposure to nitrogen dioxide is also thought to contribute to early deaths although its effects have yet to be quantified."

According to the data woodlands, grasslands and shrubs in Bournemouth and Poole absorbed 277,356 kg of air pollutants – about 25 kg of contaminants per hectare – and in Dorset 17.7 tonnes of air pollutants – about 69 kg of contaminants per hectare.

The most harmful of these substances is PM2.5, small particles with a diameter of less than 2.5 micrometres. about three per cent of the diameter of a human hair. These particles can trigger chronic disease such as asthma, heart disease, bronchitis, and cause other respiratory problems

The data also includes PM10, sulphur dioxide, nitrogen dioxide, ground-level ozone and ammonia.

Ozone was the pollutant most absorbed by plants across Dorset, making up more than 70 per cent of the total.

According to the ONS, trees account for the highest volume of air pollutants removed by vegetation.

Overall, the study shows that 1.4 billion kg of harmful substances were taken out by vegetation in the UK in 2015.

Public Health England claims the health and social care costs of air pollution in England could reach £18.6 billion by 2035 unless action is taken.

Last year, the cost was estimated to be £157 million.