Accompanying editorial to paper from Harvard by Rice et al. entitled “Long-Term Exposure to Traffic Emissions and Fine Particulate Matter and Lung Function Decline in the Framingham Heart StudyBy almost any measure the Clean Air Act and its amendments has to be considered as one of the most significant and arguably successful pieces of environmental legislation in modem times (1 ). Air quality has improved significantly since its passage and continues to do so. The levels of fine particulate matter (PM2.5) and the larger coarse particle (PMlO) have both declined by a third nationally from 2000 to 2013 ( http://www.epa.gov/airtrends/pm.html). Because these pollutants have been implicated in respiratory and cardiac diseases, this is thought to have resulted in significant health benefits with more than one study associating reduced air pollution with increased life expectancy (3, 4). Despite these improvements, more than 46 million people still live in an area where the annual average level of particle pollution is considered unhealthful.(5). The study shows that the lung function of middle aged men and women may also be reduced by long-term exposure to air pollution or traffic. Using the Framingham Offspring and Third Generation cohorts based in Massachusetts, the authors show that those individuals residing near a major road or in areas with higher PM2.5 levels have lower average FEV 1 and FVC. In addition, the natural decline in lung function with age also appeared to be accelerated in those people. No association between long-term air pollution and FEV1/ FVC ratio was apparent and so the authors conclude that the effects are not associated with airflow obstruction. The findings on lung decline complement previous longitudinal studies in children living in Southern California where PM2.5 reduced lung function growth between the ages of 10 and 18 years, the age where rapid lung development normally occurs (6). Similar associations between air pollution and deficits in lung function growth have now been seen in schoolchildren in Mexico City. (7), China (8) and Europe(9).