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6 October 2017, 14:09
Levels of several major air pollutants in Scotland have dropped by more than two thirds since 1990, new figures show.
The largest drop was recorded in lead, which fell by 99% between 1990 and 2015, followed by a 92% drop in sulphur dioxide over the same period, and an 83% fall in carbon monoxide.
Nitrogen oxide levels are down 71% over the 25 years, a group of chemicals called non-methane volatile organic compounds (NMVOCs) which include benzene, ethanol and formaldehyde have dropped 66%, while the level of tiny particles of pollutants known as PM10 has fallen 63%.
Ammonia has fallen the least since 1990, with a 10% drop.
The latest figures in the National Atmospheric Emissions Inventory report to 2015 showed little change from the previous year - ammonia increased from 36 to 37 kilotonnes (kt) in that period, while carbon monoxide dropped from 113kt to 112kt and nitrogen oxides fell by 4kt to 84kt, driven by improvements in the energy industries.
Sulphur dioxide showed the largest change year on year, falling from 30kt to 23kt, also due to a drop in energy industries, while NMVOCs rose three kt to 140kt mainly due to a rise in emissions from industrial processes including the whisky industry, which contributes around 42% of total Scottish emissions.
Both lead and PM10 remained the same at 3kt and 12kt respectively.
The report also revealed the increasing use of wood-burning stoves in homes are leading a rise in carbon monoxide and PM10 in the residential and other combustion category.
Statisticians point out the uncertainties around the estimates for any given year are "considerable" and trends over time are likely to be more reliable, with the uncertainty rating high for ammonia, carbon monoxide and PM10, moderate for NMVOCs and lead and low for nitrogen oxides and sulphur dioxide.
Environmental campaigners welcomed the drop in air pollution since 1990 but raised concerns over current pollution hotspots.
Scottish Greens environment spokesman Mark Ruskell said: "The long-term trend is downward but we have a rising number of pollution hotspots breaching legal limits with 38 town and city centres now affected across Scotland.
"It's a public health crisis that successive governments have ignored. Ministers need to step up funding and support for low emissions zones and back my proposal for a 20mph default speed limit in urban areas, as together these measures will save lives."
Friends of the Earth Scotland's Air Pollution Emilia Hanna echoed his concerns and backed calls for low emission zones.
She said: "These results look at pollution in terms of overall tonnage across the country, which is very important, but what really matters to people's lives and health are the acute concentrations of pollution that people are exposed to.
"The report makes it clear that Nitrous Oxides are concentrated along roads, particularly in urban areas. These elevated concentrations of pollutants are illegally high and are causing a public health crisis."
She added: "Air pollution, at levels we continue to see on Scottish streets, has been linked with cancers, heart attacks, strokes, and reduced foetal development."