The study by Matens and others brings together two bodies of research by relating exposure to airborne particulate pollutants during pregnancy and markers of impaired chromosome integrity in umbilical cord blood and placental samples. They report on telomere length - a marker of cellular longevity which predicts chronic disease and senescence.

The observation of a link between residential air pollution and reduced telomere length is potentially important as it suggests that air quality is important not just for the mother, but also potentially for fetal development, and by implication, the long term health of the baby.

As with most studies of association, this study needs to be replicated in different settings before we can draw firm conclusions on the estimates of risk size, source of risk, and potential long term consequences.

The study was also not entirely consistent in the direction of effects, which may be an artefact of how telomeres were assessed and from using umbilical cord rather than child blood.

Nevertheless, the study raises important questions for further work and expands the range of adverse outcomes associated with exposure to very small sized particulate air pollution.