High pollution levels for Fife, East Lothian and Borders
High levels of air pollution have been forecast for some parts of the east of Scotland and the Borders.
The risk in Fife has been described as "very high", the highest level for air pollution, while East Lothian and the Borders will have "high" levels.
Air Quality in Scotland said levels in these areas would return to "low" on Friday but on Saturday they will return to "high" in East Lothian and Fife.
Anyone with a heart or lung condition may be significantly affected.
The pollution is being caused by an area of high pressure, which creates calm weather. This allows pollutants to become trapped close to the ground.
Light winds from an easterly direction over the weekend brought air from the continent which also contained some pollution.
Adults and children with lung problems, as well as adults with heart problems, should avoid strenuous exertion, particularly when outdoors.
The risk has been classed as "moderate" for Perth and Kinross, Clackmannanshire and Edinburgh. On Friday there will be a "moderate" risk in Clackmannanshire, Stirling, Falkirk, East Dunbartonshire and North Lanarkshire.
On Saturday, the risk will also be "moderate" in Edinburgh, Midlothian, Perth and Kinross, West Lothian and Falkirk.
A Scottish government spokesperson said: "Much progress has been made over recent years in improving air quality, and Scotland is pressing ahead with world-leading climate change targets.
"However, areas of poorer air quality related to emissions from transport remain in many of our urban areas and we continue to work closely with local authorities and other partners to improve air quality and the lives and well-being of communities and individuals across the country."