The GMB said councils had to do more to identify the areas and times of day when extremely high levels of pollutants were being recorded and to make sure vulnerable people and workers, such as street cleaners, were made aware of the risk.
On the first day of its UK congress, and citing official data on the levels of nitrogen dioxide (NO2) pollutants in the air, it also called for data on pollution hotspots to be made available in doctors' surgeries.
The GMB named areas in Aberdeen and Glasgow as being amongst the worst in Britain, along with seven locations in London and six others elsewhere, including in Bath, Cambridge, Leeds and Birmingham.
In January, the Sunday Herald revealed that more than 20 of the busiest streets in Scotland's towns and cities were subject to levels of pollution breaching of safety limits, threatening the health of millions.
Four streets in Aberdeen and three in each of Dundee, Edinburgh and Glasgow, were contaminated by toxic concentrations of traffic fumes, with Falkirk, Perthshire, Lanarkshire, West Lothian, Paisley and Irvine identified as hotspots.
NO2 pollution has worsened since 2012 on Byres Road in Glasgow, Central Road in Paisley and Seagate in Dundee.
John McClean, GMB national health, safety and environment officer, called on GP surgeries to display information about the affected areas. He said: "Councils should do more monitoring to identify areas and times of day with high levels of pollutants."