Legal action over air pollution plans for devolved nations
Plans to tackle air pollution in the devolved nations are "inadequate", the High Court in London will be told later this week.
Environmental group ClientEarth is taking legal action against the UK government.
It comes after the campaigners won a case forcing ministers to publish their draft clean air strategy.
The organisation now says there is no evidence of "concrete actions" for Scotland, Wales and Northern Ireland.
The UK government's department for environment, food and rural affairs (Defra) has insisted its plan does set out steps for the devolved institutions.
The Scottish government said it has sought to shape the UK government's clean air strategy.
Last month, the government at Westminster lost a court bid to delay publication of its air pollution strategy ahead of the general election. It had argued such a move would fall foul of election "purdah" rules.
ClientEarth has been involved in the long-running legal action against the government over illegal levels of nitrogen dioxide (NO2) pollution.
Now the group of environmental lawyers is going back to the High Court on Wednesday to argue that ministers have failed to comply with the court order forcing publication of the draft guidelines.
They will say the plans contain little detail about tackling air pollution in Scotland, Wales and Northern Ireland.
Air quality is a devolved matter but the environmental group said the UK, as EU member state, was deemed responsible for enforcing legal pollution limits.
ClientEarth chief executive James Thornton said: "The draft plans for Scotland, Wales and Northern Ireland are simply plans for more plans.
"The court ordered a plan for the UK government to obey the law on pollution limits across the UK as soon as possible. The health of all UK citizens is at stake, not just some."
A spokesman for Defra said it had consulted with the devolved authorities on its proposals and the clean air plan was "for the entire UK".
He added: "Improving the UK's air quality and cutting harmful emissions is a priority for this government.
"We have invested more than £2bn since 2011 to increase the uptake of ultra-low emissions vehicles and support greener transport schemes, and set out how we will improve air quality through a new programme of Clean Air Zones."
A Scottish government spokesman said it had made "strong progress" in reducing air pollution levels and would "continue to build on these achievements".
He added: "We have already sought to shape the UK government's plan with our Clearer Air for Scotland Strategy, which sets out ambitious actions designed to secure further improvements in Scotland's air quality."