A study in one of the cleanest countries in the world could help governments think about future ways to manage air pollution. Abundant data from London’s infamous 1952 smog onwards tells us that breathing high concentrations of air pollution harms our health. This feeds into the 20th-century idea of targets for the quality of our air. However, the new study looked at the health harm from air pollution from another angle. Census records for more than 7 million Canadians from between 1981 and 2016 were combined with air pollution data to find out if small amounts of particle pollution were still harmful. Despite the relatively clean air, the study found that nearly 8,000 Canadians were dying early each year from outdoor air pollution. Notably, even people in the cleanest areas were experiencing an impact on their health. Air pollution harm was seen at concentrations that were at about one half of the latest World Health Organization guideline and at just quarter of the 2040 target proposed for England. The Canadian study was one of three funded by the US Health Effects Institute. The other two looked at more than 60 million people in the US and 27 million people in Europe. They reached similar conclusions: there is no lower limit that can be used to define safe air quality. This means governments should not constrain their ambition around setting targets for the worst air that people should breathe. Prof Michael Brauer from the University of British Columbia, who led the Canadian study, said: “These findings suggest important health benefits could be gained from continued reductions in air pollution and more stringent regulatory standards, including in countries such as Canada and the UK. “Considering that we don’t identify a ‘safe’ level of air pollution, we should rethink our approach and focus on continued reductions year by year, rather than just setting fixed concentration standards that are only reviewed every five to 10 years. The health impacts are far too large.” Last month, a UK review warned that air pollution contributes to dementia and a US review highlighted how asthma can start from being exposed to air pollution from traffic. Although UK and European countries are committed to reducing average particle pollution and the total pollution produced by each country, the growing evidence underlines the need for action to improve air pollution everywhere and especially for young and vulnerable people.