THEY provide a vital environmental boost in our towns and cities – and could even prove a game-changing weapon in the battle against an illness that kills dozens of Scots every day.

Areas with better air quality tend to have plenty of trees and grass, suggests a new study.

In turn, they are also linked with having a lower death rate from heart disease. Scientists have found that, for every 0.1 unit increase in greenness, deaths from heart disease dropped by 13 per 100,000 adults.

The research also established that the number of deaths from heart disease increased by roughly 39 per 100,000 adults for every one microgram increase in particulate matter per cubic meter of air.

It comes after statistics published last year showed that the number of Scots dying prematurely from heart disease was on the rise for the first time in 50 years and increasing at twice the rate of the UK average.

Greenness is quantified by the amount of trees, shrubs and grass in a particular area. Using this method, scientists measured it in the US by county and compared it to national disease death rates from the Centers for Disease Control and Prevention’s Interactive Atlas of Heart Disease.

They also looked at data from the Environmental Protection Agency’s air quality measurements of particulate matter for each county and the Census Bureau’s information on age, race, education and income by county.

Dr William Aitken, of the University of Miami Miller School of Medicine, said: “We found that both increased greenness and increased air quality were associated with fewer deaths from heart disease.

“We found that areas with better air quality have higher greenness, and that having higher greenness measures, in turn, is related to having a lower rate of deaths from heart disease.”

Scientists now say policymakers should support greenness by promoting fair access to green spaces, clean air and clean water.

“Given the potential cardiovascular benefits of higher greenness measures, it’s important that dialogue about improved health and quality of life include environmental policies that support increasing greenness,” said Dr Aitken.

“Policymakers should support greenness through efforts that promote environmental justice through equitable access to green spaces, clean air and clean water, as well as minimising exposure to environmental hazards.”

The team hope their findings will encourage clinical trials using built environment interventions, such as tree planting, to increase vegetative presence and greenness.

Dr Aitken added: “We will be performing a longitudinal study in Miami to assess if changes in neighbourhood greenness over time are associated with changes in cardiovascular disease.”

In the study, researchers used the Normalised Difference Vegetative Index (NDVI), which measures wavelengths of sunlight reflected from the Earth’s surface via NASA satellite imagery.

A higher index is linked to more healthy vegetation, as plants typically absorb or reflect light through photosynthesis.

The research was carried out using national air quality, greenness, CVD and census data from 2014 to 2015.

Limitations include that it was a cross-sectional study and used a total of combined cardiovascular disease death rates. Last year, figures from the British Heart Foundation (BHF) Scotland showed that heart and circulatory disease deaths in under-75s increased by almost 6 per cent between 2014 and 2017, compared to a rise of 3% t across the UK as a whole.

For under-65s, the deaths went up by 8% in Scotland compared to 4% UK-wide. The data followed decades of progress which saw death rates fall by three quarters since the 1960s, thanks in part to improvements in treatments and changing lifestyles, including declining smoking rates.

James Cant, former head of BHF Scotland, said at the time: “We’ve made phenomenal progress in reducing the number of people who die of a heart attack or stroke each day.

“But these figures show a worrying and unnecessary slowdown in the pace of progress.

“The result is that we’re still seeing too many people die each year from heart and circulatory diseases – around 50 people each day in Scotland.” Findings from the latest research will be presented at the American Heart Association’s Scientific Sessions 2020.