Researchers estimated that for every five microgrammes per cubic metre increase in annual exposure to fine-particle pollution the risk of dying from natural causes rises by 7%. The EU annual average limit is 25 microgrammes per cubic metre, but the World Health Organisation's is just 10.
Lead scientists Dr Rob Beelen said:"A difference of five microgrammes can be found between a busy urban road and at a location not influenced by traffic."
The scientists pooled data from 22 studies involving 367,251 people. Annual average air pollution concentrations of nitrogen oxides and sooty pollutants called particulates were linked to home addresses to estimate exposures. Traffic density on the nearest road and total traffic load on all major roads within 100 metres of people's homes were also recorded.
Some 29,076 participants died from natural causes during an average follow-up period of 13.9 years.
The results, published in The Lancet medical journal, showed that long-term exposure to fine particles with a diameter of less than 2.5 micrometres, called PM2.5s, posed the greatest threat to health.
Dr Richard Dixon, Director of Friends of the Earth Scotland, said: "To our credit, Scotland has tougher standards for some pollutants but we still need to work hard to reduce pollution and save lives."