Glasgow's Hope Street has come out as one of Scotland's most polluted streets in a league table published by an environmental charity.
Friends of the Earth Scotland used data gathered from roadside and kerbside monitoring stations around Scotland.
Glasgow's Hope Street was found to have the highest levels of nitrogen dioxide and fine particles in 2013, while Aberdeen's Market Street was the worst for particulate matter.
These forms of air pollution have been linked to health problems such as asthma and other respiratory conditions.
Friends of the Earth Scotland said new research has linked exposure to fine particles with heart attacks.
The charity said levels of air pollution were missing EU and UK standards in some cases.
Other streets with high levels of nitrogen dioxide include Central Road, Paisley, Seagate in Dundee and St John's Road, Edinburgh, among others.
Streets with high levels of particulate matter include Wellington Road, Aberdeen, Atholl Street in Perth, Salamander Street, Edinburgh, Union Street in Aberdeen and Irvine High Street in North Ayrshire, among others.
Emilia Hanna, air pollution campaigner for Friends of the Earth Scotland, said: "Air pollution has remained the biggest environmental threat to people in Scotland in 2013. Fumes from cars, lorries, buses and factories are killing off more people than car crashes. Air pollution is like passive smoking, we do not choose to breathe in this poisonous air, it is inflicted upon us.
"This year, as Scotland hosts the Commonwealth Games in Glasgow, and people talk of the legacy of the Games for youngsters here and across the participating nations, potential athletes of the future need clean air, not an increased risk of developing conditions such as asthma.
"Some of these targets were set in the nineties and supposed to be met in 2005, yet we still have air pollution at dangerous levels on streets across Scotland. Both the Scottish Government and our local authorities are only just beginning to take this seriously and between them they need to act urgently to make Scotland's air fit to breathe. We need action on traffic levels and the types of vehicles allowed on our most polluted streets.
"We need more investment in walking and cycling so that it is easier for people to leave their cars at home, we need cleaner and more affordable public transport, and we need to discourage the most polluting vehicles, including through the use of Low Emission Zones."