SCOTTISH ministers were told today to improve compliance with air-quality limit values after a report revealed the “continued failure” from the government.

An investigation by Environment Standards Scotland (ESS), which ensures public authorities are compliant with environmental law, found that the Scottish government has not met some targets on the statutory limits for nitrogen dioxide (NO2).

Poor air quality caused by the pollutant is recognised as being the largest environmental risk to public health.

It has been linked with a range of conditions such as cardiovascular disease and the exacerbation of asthma.

Scotland has committed to EU limit and target values which are legally binding parameters that must not be exceeded for harmful pollutants.

The report also highlighted concern that the local air-quality management framework is not robust enough to provide a comprehensive picture of local air quality, particularly around Scottish cities.

And despite long term non-compliance with NO2 limit values, existing powers to direct local authorities to take action has not been used.

The report also notes the current operational and governance arrangements to improve local air quality are “overly complex and opaque.”

The existing system in Scotland will be incapable of meeting future targets if changes are not made, experts have said.

The Scottish government has been told to prepare an improvement plan setting out how it intends to implement the recommendations in the report.

Mark Roberts, chief executive of ESS, said: “Despite efforts to improve air quality, there are still areas of non-compliance with respect to nitrogen dioxide, and these are anticipated to continue in the future.

“Given the length of time which has passed since compliance should have been achieved, and the serious impacts poor air quality can have on public health, we have decided to issue this improvement report.

“If the Scottish government decides to keep pace with European Union plans to reduce limits for nitrogen dioxide further, we do not consider that the existing system will be capable of meeting these revised limits effectively and in the shortest time possible.”

A Scottish government spokesperson said: “We welcome Environmental Standards Scotland’s report and look forward to considering their recommendations.

“Scotland already enjoys good air quality in comparison to the rest of the UK. We are committed to further improving air quality and delivering our vision for Scotland to have the cleanest air in Europe.”